Documents of the CCIR

Home , Television interference

This electronic version (PDF) was scanned by the International Telecommunication Union (ITU) Library & Archives Service from an original paper document in the ITU Library & Archives collections.

La présente version électronique (PDF) a été numérisée par le Service de la bibliothèque et des archives de l'Union internationale des télécommunications (UIT) à partir d'un document papier original des collections de ce service.

Esta versión electrónica (PDF) ha sido escaneada por el Servicio de Biblioteca y Archivos de la Unión Internacional de Telecomunicaciones (UIT) a partir de un documento impreso original de las colecciones del Servicio de Biblioteca y Archivos de la UIT.

(ITU) ﻟﻼﺗﺼﺎﻻﺕ ﺍﻟﺪﻭﻟﻲ ﺍﻻﺗﺤﺎﺩ ﻓﻲ ﻭﺍﻟﻤﺤﻔﻮﻇﺎﺕ ﺍﻟﻤﻜﺘﺒﺔ ﻗﺴﻢ ﺃﺟﺮﺍﻩ ﺍﻟﻀﻮﺋﻲ ﺑﺎﻟﻤﺴﺢ ﺗﺼﻮﻳﺮ ﻧﺘﺎﺝ (PDF) ﺍﻹﻟﻜﺘﺮﻭﻧﻴﺔ ﺍﻟﻨﺴﺨﺔ ﻫﺬﻩ .ﻭﺍﻟﻤﺤﻔﻮﻇﺎﺕ ﺍﻟﻤﻜﺘﺒﺔ ﻗﺴﻢ ﻓﻲ ﺍﻟﻤﺘﻮﻓﺮﺓ ﺍﻟﻮﺛﺎﺋﻖ ﺿﻤﻦ ﺃﺻﻠﻴﺔ ﻭﺭﻗﻴﺔ ﻭﺛﻴﻘﺔ ﻣﻦ ﻧﻘﻼ ً◌

此电子版（PDF版本）由国际电信联盟（ITU）图书馆和档案室利用存于该处的纸质文件扫描提供。

Настоящий электронный вариант (PDF) был подготовлен в библиотечно-архивной службе Международного союза электросвязи путем сканирования исходного документа в бумажной форме из библиотечно-архивной службы МСЭ.

C.C.I.R.

Xllth PLENARY ASSEMBLY

NEW DELHI, 1970

VOLUME V

PART 2

BROADCASTING SERVICE (TELEVISION) (STUDY GROUP 11) TRANSMISSION OF SOUND BROADCASTING AND TELEVISION SIGNALS OVER LONG DISTANCES (CMTT)

Published by the

INTERNATIONAL TELECOMMUNICATION UNION GENEVA, 1970 COVERING NOTE

GENERAL SECRETARIAT INTERNATIONAL TELECOMMUNICATION UNION

qeneve, 16 July 1973 Subject: Documents of the . PLACE DES NATIONS Xllth Plenary Assembly of the C.C.I.R. New Delhi - 1970 Addendum No. 2 to Volume V

Please find attached Addendum No. 2 to Volume V, in English.

Union Internationale des telecommunications 1211 GENEVE 20 Suiate - Switzerland - Suiza July, 1973

ADDENDUM No. 2

VOLUME V

Xllth PLENARY ASSEMBLY OF THE C.C.I.R. New Delhi, 1970

Note by the Director, C.C.I.R.

Subsequent to the publication of Addendum No. 1 to Volume V (Broadcasting service (sound and television), Transmission of sound broadcasting and television signals over long distances) of the documents of the Xllth Plenary Assembly of the C.C.I.R., new texts relating to the transmission of sound broadcasting and television signals over long distances have been submitted for adoption by correspondence, in conformity with the provisions of No. 190 of the International Telecommunication Convention, Montreux, 1965. These have received more than the twenty approvals necessary for their adoption by the Members of the I.T.U. and have therefore become official Questions of the C.C.I.R. These texts, which should be included in Part 2, are: — Question lOjCMTT, which is reproduced on a separate sheet numbered 317-1 a. — Question lljCMTT, which is reproduced on a separate sheet numbered 318. Advantage has been taken of the issue of this Addendum to notify the following correction to Volume V: Part 1 Page 226, § 6.2, last line: Replace “(40 ± 10)%” by “36% to 44%”. — 166 a —

QUESTION 25/11*

STANDARDS FOR TELEVISION SYSTEMS USING DIGITAL MODULATION

(1972)

The C.C.I.R.,

CONSIDERING

(a) that the C.C.I.T.T. are studying the transmission standards to be used on future digitally coded television systems; (b) that, in view of the development of digital methods of processing, transmitting and record ing signals, it is possible that these techniques will be widely used in television; (c) that, to facilitate international exchanges of programmes and to rationalize the design of equipment, it would be desirable to standardize as far as possible the methods used for the digital coding of television signals; ' (d) that digital signal processing, if used in television studios, could lead to improved reliability and performance;

decides that the following question should be studied:

1. what methods should be used for the digital coding of picture signals and the associated sound signals, and what would be the resulting advantages: — inside the studio complex, including the recording of television signals; — in the transmission of television signals on terrestrial channels Using digital modulation; — in the transmission of television signals on satellite channels; — in direct broadcasting from satellites;

2. is there a single method of digital coding which would be suitable for all the uses described in § 1;

3. what digital standards should be recommended for the applications mentioned in § 1;

4. what is the simplest and most effective technique for monitoring digitally coded television and associated sound signals?

* This Question is identical with Question 10/CMTT.

Addendum No. 2 to Volume V, part 2, Xllth P.A. of the C.C.I.R., New Delhi, 1970 - 3 1 7 - l a —

QUESTION 10/CMTT

STANDARDS FOR TELEVISION SYSTEMS USING DIGITAL MODULATION

(1972) '

The C.C.I.R.,

CONSIDERING

(a) that the C.C.I.T.T. are studying the transmission standards to be used on future digitally coded television systems; (b) that, in view of the development of digital methods of processing, transmitting and record ing signals, it is possible that these techniques will be widely used in television; (c) that, to facilitate international exchanges of programmes and to rationalize the design of equipment, it would be desirable to standardize as far as possible the methods used for the digital coding of television signals; (d) that digital signal processing, if used in television studios, could lead to improved reliability and performance;

decides that the following question should be studied:

1. what methods should be used for the digital coding of picture signals and the associated sound signals, and what'would be the resulting advantages : — inside the studio complex, including the recording of television signals; — in the transmission of television signals on terrestrial channels using digital modulation; — in the transmission of television signals on satellite channels; — in direct broadcasting from satellites;

2. is there a single method of digital coding which would be suitable for all the uses described in § 1;

3. what digital standards should be recommended for the applications mentioned in § 1;

4. what is the simplest and most effective technique for monitoring digitally coded television and associated sound signals?

Note by the Secretariat. — During the final meetings of Study Groups 10, 11 and the CMTT (Geneva, 1974), it would be highly desirable to modify the text of this Question so that Study Programme 10A/CMTT could be considered as being entirely derived from it (both as regards that part concerning television and that part concerning sound broadcasting).

Addendum No. 2 to Volume V, part 2, Xllth P.A. of the C.C.I.R., New Delhi, 1970 — 318 —

QUESTION 11/CMTT

PERFORMANCE CHARACTERISTICS OF 5 kHz-TYPE SOUND PROGRAMME CIRCUITS

(1972) The C.C.I.R.,

CONSIDERING

(a) that, according to Opinion 41, the CMTT should study circuits with “a narrow bandwidth of about 100 Hz-5 kHz” (nominal bandwidth); (b) that new C.C.I.T.T. Recommendations J.23 and J.24 (provisional reference: C.C.I.T.T. White Book, Mar del Plata, 1968, Volume III, Recommendations J.31 and J.41 for normal sound programme circuits, type B, and for old-type sound programme circuits respectively) can only be applied to a limited degree to the circuits mentioned under (a) and thus should be replaced by an up-to-date comprehensive recommendation;

decides that the following question should be studied:

what should be the performance characteristics of a new type of sound programme circuit (designated by convention as “5 kHz-type sound programme circuit”) including the follow ing points: 1. definition of the hypothetical reference circuit; 2. nominal bandwidth and frequency band effectively transmitted; 3. permissible attenuation distortion; 4. permissible phase distortion; 5. permissible weighted and unweighted noise (with the definition of an appropriate weighting network); 6. permissible intelligible crosstalk; 7. permissible variation in relative level with time; 8. permissible non-linearity distortion; 9. permissible error on frequency reconstitution, etc.? Note 1. — Study Programme 5-1D-1/CMTT could be extended to include the effect of band width restriction. Note 2. — There may be two categories of use for such circuits, one for commentary purposes and the other also including transmission of music. If it seems advisable to recommend different characteristics for these two cases, this should be stated. Note 3. — Such circuits may be set up on carrier analogue systems and also on PCM systems; in the latter case, the permissible quantizing distortion should be stated. Note 4. — The CMTT should consider whether recommendations on intermodulation distortion should be given in addition to those on harmonic distortions. If so, how should the inter modulation distortion be measured?

Addendum No. 2 to Volume V, part 2, XHth P.A. of the C.CJ.R., New Delhi, 1970 COVERING NOTE

GENERAL SECRETARIAT INTERNATIONAL TELECOMMUNICATION UNION

e . QENfevE, 16 July 1973 Subject: Documents of the p l a c e o e s n a t i o n s Xllth Plenary Assembly of the C.C.I.R. New Delhi - 1970 Addendum No. 1 to Yolume V

Please find attached Addendum No. 1 to Yolume V, in English.

Union Internationale do# telecommunications 1211 GENEVE 20 Suisse - Switzerland • Suiz* June, 1973

ADDENDUM No. 1

VOLUME V

Xllth PLENARY ASSEMBLY OF THE C.C.I.R.

New Delhi, 1970

Note by the Director, C.C.I.R. Subsequent to the publication of Volume V (Broadcasting service (sound and television), Transmission of sound broadcasting and television signals over long distances) of the documents of the Xllth Plenary Assembly of the C.C.I.R., new texts relating to these fields have been sub mitted for adoption by correspondence, in conformity with the provisions of No. 190 of the International Telecommunication Convention, Montreux, 1965. These have received more than the twenty approvals necessary for their adoption by the Members of the I.T.U. and have therefore become official Study Programmes of the C.C.I.R. These texts are: — Study Programmes 20-1 Cj 10 and 36Aj 10, the texts of which are reproduced on separate sheets numbered 195 a and 209 a (to be included in Part 1); — Study Programmes 5-1G/11 and 10A/CMTT, the texts of which are reproduced on separate sheets numbered 153 a and 317-2 (to be included in Part 2). — 153 a —

STUDY PROGRAMME 5-1G/11*

BROADCASTING-SATELLITE SERVICE IN THE 12 GHz BAND

(1972) The C.C.I.R*

CONSIDERING

(b) that this band is also allocated on a primary basis to other services, the requirements of which must be respected;

(c) that there may, in due course, be a very substantial demand for frequency assignments for the broadcasting-satellite service in this band;

(d) that it is important to make the best possible use of the geostationary-satellite orbit and of the frequency band allocated to the broadcasting-satellite service;

(e) that whenever possible the “ service area” should be the minimum necessary to provide the required coverage;

(f) that it is necessary to prepare plans on a world-wide or regional basis for the establishment of broadcasting-satellite services (see Resolution No. Spa2 -2 );

decides that the following studies should be carried out:

determination of the essential planning parameters to be recommended for the preparation of a frequency plan for the broadcasting-satellite service in the 12 GHz band.

* This Study Programme is identical to Study Programme 20-1C/10.

Addendum No, 1 to Volume V, part 2, Xllth P.A. of the C.CJ.R., New Delhi, 1970 — 195 a —

STUDY PROGRAMME 20-1C/10*

BROADCASTING-SATELLITE SERVICE IN THE 12 GHz BAND

(1972) The C.C.I.R.,

CONSIDERING

(a) that the World Administrative Radio Conference for Space Telecommunications (Geneva, 1971) allocated a band of frequencies at about 12 GHz on a primary basis for the broadcasting-satellite service; 1 (b) that this band is also allocated on a primary basis to other services, the requirements of which must be respected;

(c) that there may, in due course, be a very substantial demand for frequency assignments for the broadcasting-satellite service in this band;

(d) that it is important to make the best possible use of the geostationary-satellite orbit and of the frequency band allocated to the broadcasting-satellite service;

(e) that whenever possible the “ service area” should be the minimum necessary to provide the required coverage;

(f) that it is necessary to prepare plans on a world-wide or regional basis for the establishment of broadcasting-satellite services (see Resolution No. Spa2-2);

decides that the following studies should be carried out:

determination of the essential planning parameters to be recommended for the preparation of a frequency plan for the broadcasting-satellite service in the 12 GHz band.

------i * This Study Programme is identical to Study Programme 5-1G/11. ♦

Addendum No. 1 to Volume V, part 1, Xllth P.A. of the C.C.I.R., New Delhi, 1970 — 209 a —

STUDY PROGRAMME 36A/10*

CHARACTERISTICS OF SOUND BROADCASTING RECEIVERS AND RECEIVING ANTENNAE

(1972) The C.C.I.R.

decides that the following studies should be carried out: ♦ 1. determination of the main characteristics of receiving installations, receivers and antennae which may be useful for frequency planning work, particularly by Administrative Confer ences, the I.F.R.B. and other organizations concerned;

2. feasibility of assembling data on the technical characteristics of receivers and antennae and their installation, in a single section of the C.CJ.R. books;

3. incorporation of the data of Recommendations 415 and 416 on low-cost receivers and the results of Study Programme 20-1B/10 concerning satellite broadcast receiving installations into the results of the present study.

Note 1, — In carrying out these studies, account should be taken of the relevant IEC publications. The IEC should be informed of the C.C.I.R.’s requirements and invited to comment (See Opinion 32).

Note 2. — The above-mentioned studies relate to all types of sound broadcasting receivers: AM and FM receivers, monophonic and stereophonic receivers, AM or FM multiplex receivers.

Since this Study Programme depends upon three Questions, namely, Questions 15/10, 17-1/10 and 25/10, new drafts having been proposed in respect of the last two, the Director, C.C.I.R., considers that at the moment it is preferable to regard this Study Programme as not deriving from a Question.

Addendum No. 1 to Volume V, part 1, Xllth P.A. of the C.C.I.R., New Delhi, 1970 — 317-2 —

STUDY PROGRAMME 10A/CMTT*

DIGITAL TRANSMISSION OF TELEVISION AND SOUND PROGRAMME SIGNALS

(1972) The C.C.I.R.,

CONSIDERING

(a) that work on digital transmission of television and sound programme signals is already in progress;

(b) that the C.C.I.T.T. has already initiated a study of digital transmission networks in which provision has been made for sound programme and television signals;

(c) that, to facilitate international exchange of programmes and to simplify the design of equip ment, it would be desirable to standardize as far as possible methods of encoding for digital transmission of television and sound programme signals;

(d) that information relating to the requirements for digital transmission of television and sound programme signals over long distances is not yet available;

decides that the following studies should be carried out:

1. methods to be recommended (including error protection if needed) for the conversion of analogue television and sound programme signals into digital signals for the purpose of transmitting them over digital links and the parameters to be specified for the recommended methods;

2. what methods can be recommended for the code conversion of digital television and sound programme signals including, where necessary, error protection, when considering trans mission of these signals over digital links, and what parameters should be specified for the recommended code conversion methods;

3. definition of hypothetical reference circuits and chains, which include digital as well as analogue sections;

4. requirements for the transmission of television and sound programme signals over hypo thetical reference circuits or chains having digital sections;

5. methods of measurement, and test signals to be recommended, for checking performance when digital transmission is used.

* This Study Programme does not derive from any Question at present under study. Any contribution sub mitted in response to this Study Programme should be drawn to the attention of Study Groups 10 and 11.

Addendum No. I to Volume V, part 2, Xllth P.A. of the C.C.I.R., New Delhi, 1970 May, 1971

CORRIGENDUM No. 1 TO VOLUME V OF THE XHth PLENARY ASSEMBLY OF THE C.C.I.R. New Delhi, 1970

Note by the Director, C.C.I.R. 1. Subsequent to the Xllth Plenary Assembly of the C.C.I.R., New Delhi, February 1970, a new Question entitled “Study of a domestic or regional satellite system for telecommunic ations and sound and television broadcast transmission” was adopted at the meeting of the Plan Committee for Asia and Oceania, Teheran, May-June 1970. The study of this Question was entrusted to the C.C.I.R. The Question was initially assigned to C.C.I.R. Study Groups 10 and 11 under the numbers 35/10 and 24/11. Following a meeting which took place between the Chairmen concerned and the Director of the C.C.I.R. during the Special Joint Meeting at Geneva, February-March 1971, it was decided that this Question fell rather more within the competence of the CMTT and it was assigned to the CMTT under the number 9/CMTT.

2. Consequently, a number of corrections become necessary and these are listed below. 2.1 In Volume V, part 1: 2.1.1 on page 209, Question 35/10 and its footnote are to be deleted; 2.1.2 on page 12, in the index, the entry relating to Question 35/10 is to be deleted. 2.2 In Volume V, part 2: 2.2.1 on page 166, Question 24/11 and its footnote are to be deleted; 2.2.2 on page 11, in the index, the entry relating to Question 24/11 is to be deleted; 2.2.3 page 317 should be replaced by the new page 317-1 annexed hereto ; 2.2.4 on page 13, in the index, insert the following entry after that relating to Question 8/CMTT and before that entitled “ resolutions” : “Question 9/CMTT Study of a domestic or regional satellite system for tele communications and sound and television broadcast transmis sion...... 317-1”. — 317-1 — Op. 41, Q. 9/CMTT

— an intermediate bandwidth, for example 10 kHz. C.C.I.T.T. Recommendation J.21 specifies a circuit which would be in this category. The above takes account of the views of the broadcasting authorities;

7. that consideration of this subject should continue with the cooperation of the broadcasting authorities.

QUESTION 9/CMTT

STUDY OF A DOMESTIC OR REGIONAL SATELLITE SYSTEM FOR TELECOMMUNICATIONS AND SOUND AND TELEVISION BROADCAST TRANSMISSION

The Plan Committee for Asia and Oceania, (1970)

CONSIDERING, ' (a) that the costs of communication satellites and earth stations have greatly decreased during the past few years; (b) that the cost of leasing a large number of telephone and television channels from International Communication Satellite Systems for domestic or regional use may be uneconomical; (c) that the economic aspects of coaxial cable and radio-relay systems are being studied by C.C.I.T.T./C.C.I.R. Special Autonomous Working Party 3 (GAS 3), but comparable studies have not been carried out by the I.T.U. for communication-satellite system; (d) that a group of countries might share the cost on a regional basis;

requests the Director, C.C.I.R., to arrange for the study of the technical and economic aspects for a domestic and/or regional , satellite system, which would provide good quality telecommunications, television and sound broadcast transmissions to meet the desired requirements. As far as possible the economic studies to be carried out should be in accordance with the methods indicated in the GAS 3 Manual. May, 1971

CORRIGENDUM No. 1 TO VOLUME V OF THE Xllth PLENARY ASSEMBLY OF THE C.C.I.R. New Delhi, 1970

2. Consequently, a number of corrections become necessary and these are listed below. 2.1 In Volume V, part 1: 2.1.1 on page 209, Question 35/10 and its footnote are to be deleted; 2.1.2 on page 12, in the index, the entry relating to Question 35/10 is to be deleted. 2.2 In Volume V, part 2: 2.2.1 on page 166, Question 24/11 and its footnote are to be deleted; 2.2.2 on page 11, in the index, the entry relating to Question 24/11 is to be deleted; 2.2.3 page 317 should be replaced by the new page 317-1 annexed hereto; 2.2.4 on page 13, in the index, insert the following entry after that relating to Question 8/CMTT and before that entitled “ resolutions” : “Question 9/CMTT Study of a domestic or regional satellite system for tele communications and sound and television broadcast transmis sion...... 317-1”. INTERNATIONAL RADIO CONSULTATIVE COMMITTEE

C.C.I.R.

Xllth PLENARY ASSEMBLY NEW DELHI, 1970

VOLUME V

PART 2

BROADCASTING SERVICE (TELEVISION) (STUDY GROUP 11)

TRANSMISSION OF SOUND BROADCASTING AND TELEVISION SIGNALS OVER LONG DISTANCES (CMTT)

Published by the INTERNATIONAL TELECOMMUNICATION UNION GENEVA, 1970 PAGE INTENTIONALLY LEFT BLANK

PAGE LAISSEE EN BLANC INTENTIONNELLEMENT RECOMMENDATIONS AND REPORTS

11A Characteristics of systems for monochrome and colour television 11B International exchange of television programmes BROADCASTING SERVICE 11C Picture quality and the parameters affecting it (TELEVISION) 11D Elements for planning

QUESTIONS AND STUDY PROGRAMMES, RESOLUTIONS AND OPINIONS

(Study Group 11)

RECOMMENDATIONS AND REPORTS

CMTT A Television transmission standards

CMTT B Measurements, monitoring, maintenance TRANSMISSION OF SOUND BROADCASTING CMTT C Joint transmission of sound and vision AND TELEVISION signals SIGNALS OVER LONG CMTT D Sound programme transmission DISTANCES

QUESTIONS AND STUDY PROGRAMMES,. RESOLUTIONS AND OPINIONS

(CMTT) PAGE INTENTIONALLY LEFT BLANK

PAGE LAISSEE EN BLANC INTENTIONNELLEMENT DISTRIBUTION OF TEXTS OF THE Xllth PLENARY ASSEMBLY OF THE C.C.I.R. IN VOLUMES I TO Vfl

Volumes I to VII, Xllth Plenary Assembly, contain all the valid texts of the C.C.I.R.

1. Recommendations, Reports, Resolutions, Opinions

1.1 Numbering o f these texts

Recommendations, Reports, Resolutions and Opinions are numbered according to the system in force since the Xth Plenary Assembly. When one of these texts is modified, it retains its number to which is added a dash and a figure indicating how many revisions have been made. For example: Recommendation 253 indicates the original text is still current; Recommendation 253-1 indicates that the current text has been once modified from the original, Recommendation 253-2 indicates that there have been two successive modifications of the original text, and so on. The Tables which follow show only the original numbering of the current texts, without any indication of successive modifications that may have occurred. For further information about this numbering scheme, please refer to Volume VII of the C.C.I.R.

1.2 Recommendations

Number Volume Number Volume Number Volume

45 VI 265, 266 V 374-376 III 48, 49 V 268 IV 377-379 I 77 VI 270 IV 380-393 IV 80 V 275, 276 IV 395-406 IV 100 I 279 IV 407-421 V 106 III 283 IV 422, 423. VI 139, 140 V 289, 290 IV 427-429 VI 162 III 302 IV 430, 431 III 166 I 304-306 IV 432, 433 I 182 I 310, 311 II 434, 435 II 205 V 313 II 436 III 214-216 V 314 IV 439-441 VI 218, 219 VI 325-334 I 442, 443 I 224 VI 335-340 III 444-446 IV 237 I 341 I 447-451 V 239 I 342-349 III 452, 453 II 240 III 352-359 IV 454-461 III 246 III 361 VI 462-466 IV 257, 258 VI 362-367 IV 467-474 V 262 V 368-373 II 475-478 VI — 6 —

1.3 Reports

Number • Volume Number Volume Number Volume

19 III 226 IV 341-344 II 32 V 227-231 II 345-357 III 42 III 233-236 II 358, 359 VI 79 V 238, 239 II 361 VI 93 VI 241 II 362-364 III 106, 107 III 244-251 II 366 III 109 III. 252 0 367-373 I 111 Ill 253-256 II 374-393 IV 112 I 258-266 II 394 VI 122 V 267 III 395-397 IV 130-137 IV 269-271 III 398-401 V 176-194 I 272, 273 I 403-407 V 195 III 275-282 I 409-412 V 196 I 283-290 IV 413-415 0 197, 198 III 292-294 V 416-423 I 200, 201 III 297-308 V 424-432 II 202 I 311-316 V 433-439 III 203 III 318-320 VI 440 0 204-214 IV 321 III 441 III 215 V 322 0 442-456 IV 216 VI 324-334 I 457-498 V 218, 219 IV 335 III 499-515 VI 222-224 IV 336-339 II 516 V 340 0

(l) Published separately.

1.4 Resolutions

Number Volume Number Volume Number Volume

2-4 II 21-23 III 39, 40 VII 7, 8 II 24 VII 41-44 I 10 II 26, 27 VII 45-51 II 12, 13 II 30 II 52-54 III 14 III 33 VII 55, 56 IV 15, 16 I 36, 37 VII 57, 58 V 20 VI 38 1\ VIIY

1.5 Opinions

Number Volume Number Volume Number Volume

2 I 22, 23 II 32-35 I 11 I 24 VI 36, 37 III 13, 14 IV 26-28 III 38-41 V 15, 16 V 29, 30 I 42, 43 VI — 7 —

2. Questions and Study Programmes

2.1 Text numbering

2.1.1 Questions

Questions are numbered in a different series for each Study G roup; where appli cable a dash and a figure added after the number of the Question indicate successive modifications. The number of a Question is completed by an Arabic figure indicating the relevant Study Group. For example: — Question 1/10 would indicate a Question of Study Group 10 with its text in the original state; — Question 1-1/10 would indicate a Question of Study Group 10, whose text has been once modified from the original; Question 1-2/10 would be a Question of Study Group 10, whose text has had two successive modifications.

2.1.2 Study Programmes Study Programmes are numbered to indicate the Question from which they are derived if any, the number being completed by a capital letter which is used to distin guish several Study Programmes which derive from the same Question. For example: — Study Programme 1A/10, which would indicate that the current text is the original version of the text of the first Study Programme deriving from Question 1/10; — Study Programme 1C/10, which would indicate that the current text is the original version of the text of the third Study Programme deriving from Question 1/10; — Study Programme 1 A-1 /10 would indicate that the current text has been once modified from the original, and that it is the first Study Programme of those deriving from Question 1/10; — Study Programme 3-1A/10 would indicate that the current text is the original and that this Study Programme is the first deriving from Question 3-1/10, which has itself been once modified from the original; — Study Programme 3-1B-1/10 would indicate that the current text has been once modified from the original, and that this Study Programme is the second of the group deriving from Question 3-1/10, which has itself been once modified from the original. It should be noted that a Study Programme may be adopted without it having been derived from a Question; in such a case it is simply given a sequential number analogous to those of other Study Programmes of the Study Group, except that on reference to the list of relevant Questions it will be found that no Question exists corresponding to that number. Also, the up-to date number of the Question concerned is used in assembling the number of a Study Programme: this is to facilitate reference to the Volumes, but does not exclude the possibility of the Study Programme having been evolved before the latest version of the Question.

2.2 Arrangement o f Questions and Study Programmes The plan shown on page 8 indicates the Volume in which the texts of each Study Group are to be found, and so reference to this information will enable the text of any desired Question or Study Programme to be located. PLAN OF VOLUMES I TO VII XHth PLENARY ASSEMBLY OF THE C.C.I.R.

(New Delhi, 1970)

Volume I Spectrum utilization and monitoring (Study Group 1).

Volume II Propagation in non-ionized media (Study Group 5). (Part 1)

Volume II Ionospheric propagation (Study Group 6). (Part 2)

Volume III Fixed service at frequencies below about 30 MHz (Study Group 3). Standard frequencies and time signals (Study Group 7). Vocabulary (CIV).

Volume IV Fixed service using radio-relay systems (Study Group 9). Coordination and fre (Part 1) quency sharing between communication-satellite systems and terrestrial radio relay systems (subjects common to Study Groups 4 and 9).

Volume IV Fixed service using communication satellites (Study Group 4). Space research (Part 2) and radioastronomy (Study Group 2).

Volume V Broadcasting service (sound) (Study Group 10). Problems common to sound (Part 1) broadcasting and television (subjects common to Study Groups 10 and 11).

Volume V Broadcasting service (television) (Study Group 11). Transmission of sound (Part 2) broadcasting and television signals over long distances (CMTT).

Volume VI Mobile services (Study Group 8).

Volume VII Information concerning the Xllth Plenary Assembly. Structure of the C.C.I.R. Complete list of C.C.I.R. texts.

Note. — To facilitate reference, page numbering is identical in all three versions of each Volume, that is, in English, French and Spanish. VOLUME V

Part 2

INDEX *

BROADCASTING SERVICE (TELEVISION) (Study Group 11)

TRANSMISSION OF SOUND BROADCASTING AND TELEVISION SIGNALS OVER LONG DISTANCES (CMTT) Study Group 11 Page Introduction by the Chairman, Study Group 11 15 s e c t io n 11 A: Characteristics of systems for monochrome and colour television ...... 17 s e c t io n 1 IB: International exchange of television programmes ...... 73 s e c t io n 11C: Picture quality and the parameters affecting it ...... 83 se c t io n 1 ID: Elements for planning...... 101

RECOMMENDATIONS Section Rec. 266 Phase correction of television transmitters necessitated by the use of vestigial-sideband transm ission 11D 101 Rec. 417-2 Minimum field strengths for which protection may be sought in planning a television service 11D 102 Rec. 418-2 Ratio of the wanted-to-unwanted signal in monochrome'television . . 11D 103 Rec. 419 Directivity of antennae in the reception of broadcast sound and tele vision 11D 113 Rec. 470 Television systems 11A 17 Rec. 471 Nomenclature of colour bar sig n a ls 11A 17 Rec. 472 Video-frequency characteristics of a television system to be used for the international exchange of programmes between countries that have adopted a 625-line monochrome system 11B 73

REPORTS Report 122-1 Advantages to be gained by using orthogonal wave polarizations, in the planning of broadcasting services in bands 8 (VHF) and 9 (UHF). Sound and television 11D 114 Report 306-1 Ratio of wanted-to-unwanted signal for colour television...... 11D 116 Report 307 Protection ratios for television in the shared bands. Protection against radionavigation transmitters operating in the band 582 to 606 MHz . . . 11D 121 Report 308-2 Characteristics of monochrome television system s...... 11A 21 Report 311-2 The present position of standards conversion 11B 75 Report 312-2 Constitution of a system of stereoscopic television...... 11A 36 Report 313-2 Assessment of the quality of television p ic tu re s...... 11C 83 Report 315-2 Reduction of the channel capacity required for the transmission of a television signal...... 11D 123 Report 404-1 Distortion of television signals due to the use of vestigial-sideband transmission...... 11C 85

* In this Volume, Recommendations and Reports dealing with the same subject are collected together. These texts are numbered in such a manner that they cannot be presented in numerical order and at the same time, in numerical sequence of pages. Consequently, this index, in numerical order of texts, does not follow the numerical sequence of pages. — 10 — Section Page Report 405-1 Subjective assessment of the quality of television pictures...... l i e 89 Report 406 Colour television...... 11A 37 Report 407-1 Characteristics of colour television system s...... 11A 49 Report 409-1 Boundaries of the television service area in rural districts having a low population density...... 11C 96 Report 476 Colorimetric standards in colour television...... 11A 72 Report 477 Transcoding of colour television signals from one colour system to another ...... 11B 82 Report 478 Ghost images in monochrome television. Re-radiation from masts in the neighbourhood of transmitting a ntennae...... 11C 97 Report 479 Protection ratios for television when both wanted and unwanted signals are substantially non-fading...... 11D 125 Report 480 Protection ratios for non-precision offsets between television signals that are multiples of one-twelfth line-frequency...... 11D 127 Report 481 Ratio of wanted-to-unwanted signal in television. Subjective assessment of multiple co-channel interference...... 11C 99 Report 482 Recommended characteristics for collective and individual antenna systems for domestic reception of signals from terrestrial transmitters . 11D 128 Report 483 Specifications for low-cost television receivers...... 11D 131 Report 484 Ratio of picture-signal to synchronizing-signal...... 11D 135 Report 485 Contribution to the planning of broadcasting services. Statistics of service...... 11D 136

QUESTIONS AND STUDY PROGRAMMES

Question 1/11 Colour television standards...... 141 Study Programme 1 A/11 * Standards for video colour-television signals ...... 142 Study Programme IB/11 Standards for radiated colour-television sig n a ls...... 142 Study Programme 1 C/ll Constitution of a system of stereoscopic television...... 142 Study Programme ID/11 Ratio of picture-signal to synchronizing-signal...... 143 Study Programme IE/11 Simplification of synchronizing signals in television ...... 144 Study Programme IF/11 Allocation of tolerances for colour television...... 144 Question 2-1/11 Exchange of television program m es...... 145 Study Programme 2-1 A/11 Transcoding of colour television signals from one system to another ...... 145 Question 3-1/11 Assessment of the quality of television pic tu re s...... 146 Study Programme 3-1 A/ll Subjective assessment of the quality of television pictures . . . 146 Question 4-1/11 Ratio of the wanted-to-unwanted signal in television...... 147 Study Programme 4-1 A/ll Ratio of the wanted-to-unwanted signal in television. Use of the offset method, when there are great differences between the carrier-frequencies of the interfering s ta tio n s...... 148 Question 5-1/11 Broadcasting satellite service. Television...... 148 Study Programme 5-1 A/11 World-wide standard for television broadcasting from satellites . 149 Study Programme 5-1B/11 Composite 625-line signal for television broadcasting from satellites...... 150 Study Programme 5-1 C/ll Possible broadcasting-satellite systems for television and their relative acceptability...... 150 Study Programme 5-1D/11 Broadcasting satellite service (television) for community reception...... 151 Study Programme 5-1E/11 Broadcasting satellite service (television). Types of modulation for bands 9 and 1 0 ...... 152 Study Programme 5-1F/11 Characteristics of a television receiving system for direct trans mission from satellites...... 152 — 11 — Page Question 6/11 Ghost images in television...... 153 Study Programme 6A/11 Ghost images in television...... 153 Question 7-1/11 Recommended characteristics for individual or collective television antenna systems for domestic reception of signals from terrestrial transmitters .... 154 Study Programme 9A/11 Distortion of television signals due to the use of a vestigial-side band emission 154 Study Programme 10A/11 Conversion of a television signal from one standard to another . . 155 Study Programme 11 A/11 Reduction of the channel capacity required for a television signal . . 155 Study Programme 12A/11 Insertion of special signals in the field-blanking interval of a tele vision signal 156 Question 13/11 Specifications for low-cost television receivers...... 156 Question 14/11 Subjective quality targets of overall television sy ste m s...... 157 Study Programme 14A/11 Subjective quality targets of overall television systems .... 157 Question 15/11 Automatic monitoring of television stations ...... 158 Question 16/11 Standards for the international exchange of monochrome television programmes. Film recording and reproducing ...... 159 Question 17/11 Optical sound recording and reproducing standards for the international exchange of television programmes...... 160 Question 18/11 Recording of television signals on magnetic ta p e ...... 160 Study Programme 18A/11 Recording of television signals on magnetic ta p e ...... 161 Study Programme 18B/11 Standards for the international exchange of television programmes on magnetic tape. Helical-scan recording ...... 161 Study Programme 18C/11 Measuring methods for television tape recording...... 162 Question 19/11 Magnetic sound recording and reproducing standards for the international exchange of television programmes on film. Recording and reproducing charac teristics for 16 SEPMAG and 16 COMMAG ...... 162 Question 20/11 Recording of colour television signals on film ...... 163 Question 21/11 Standards for the international exchange of colour television programmes. Film recording and reproducing ...... 163 Question 22/11 Methods of synchronizing various recording and reproducing systems .... 164 Study Programme 22A/11 Recording of coded information on the cue track of television magnetic tapes...... 164 Question 23/11 Feasibility of direct sound and television broadcasting from satellites...... 165 Question 24/11 Study of a domestic or regional communication-satellite system for telecommuni cations and sound and television broadcasting...... 166

RESOLUTIONS

Resolution 38 Possible broadcasting satellite systems and their relative acceptability...... 166 Resolution 58 Assessment of the quality of pictures in television systems ...... 167

OPINIONS

Opinion 38 Exchange of monochrome and colour television programmes via satellites .... 169 Opinion 39 Characteristics of television antennae for domestic u s e ...... 169 Opinion 40 Subjective assessment of the quality of television pictures...... 170 — 12 — CMTT

Introduction by the Chairman, CMTT ...... 171 s e c t io n CMTT A: Television transmission standards ...... 173 s e c t io n CMTT B : Measurements, monitoring, maintenance ...... 237 s e c t io n CMTT C : Joint transmission of sound and vision sig n a ls...... 259 s e c t io n CMTT D : Sound programme transm ission...... 265

recommendations Section Rec. 420-2 Insertion of special signals in the field-blanking interval of television signals (monochrome o n ly ) CMTT B 237 Rec. 421-2 Requirements for the transmission of television signals over long distances (System I excepted) CMTT A 173 Rec. 451-1 Requirements for the transmission of television signals over long distances (System I o n ly ) CMTT A 193 Rec. 473 Insertion of special signals in the field-blanking interval of a television s ig n a l CMTT B 239 Rec. 474 Modulation of signals carried by sound programme circuits by inter fering signals from power supply sources CMTT D 265

r e p o r t s

Report 314-2 Insertion of special signals in the field-blanking interval of a television signal...... CMTT B 250 Report 316-1 Requirements for the transmission of television signals over long distances...... CMTT A 214 Report 410-1 Single value of the signal-to-noise ratio for all television systems . . CMTT A 216 Report 411-1 Automatic remote monitoring of the performance of television chains CMTT B 253 Report 412-1 Transmission time differences between the sound and vision compo nents of a television s ig n a l...... CMTT C 259 Report 486 Transmission performance of television circuits designed for use in international connections...... CMTT A 218 Report 487 Television reference chains for terrestrial and communication- satellite lin k s ...... CMTT A 236 Report 488 Transmission of sound and vision signals by time-division multiplex . CMTT C 261 Report 489 Circuits for high quality monophonic programme transmissions . . CMTT D 266 Report 490 Characteristics of circuits currently offered for transmission of sound programme signals over long distances...... CMTT D 267 Report 491 Characteristics of signals sent over sound programme circuits . . . CMTT D 267 Report 492 Revision of C.C.I.T.T. Recommendation J .2 1 ...... CMTT D 280 Report 493 Compandors for programme circuits...... CMTT D 282 Report 494 Transmission of sound programme signals over long distances . . . CMTT D 285 Report 495 Noise from the power su p p ly ...... CMTT D 285 Report 496 Circuits for high quality monophonic and stereophonic transmissions CMTT D 286 Report 497 Circuits for high quality monophonic and stereophonic transmissions. A proposed test signal and weighting network for use in making tests for linear and non-linear crosstalk andlor non-linearity...... CMTT D 298 Report 498 Transmission of sound programme signals over communication- satellite lin k s ...... CMTT D 301

I — 13 — Page QUESTIONS AND STUDY PROGRAMMES

Question 1-1/CMTT Transmission of television signals over long distances ...... 303 Study Programme 1-1B-1/CMTT Performance requirements for international television circuits...... 303 Study Programme 1-1C/CMTT Insertion of special signals in the field-blanking interval of a television sig n al...... 304 Study Programme 1-1D/CMTT Damped very low frequency oscillations in television circuits over long distances...... 305 Study Programme 1-1E/CMTT Allocation of tolerances for colour television...... 305 Question 2-1/CMTT Reference chains for television. Application to real terrestrial chains longer than 2500 km and to chains including communication-satellite links..... 306 Study Programme 2-1A/CMTT Television reference chains for terrestrial and communi cation-satellite l i n k s ...... 306 Question 4-1/CMTT Differences in transmission time between the sound and picture components of a television signal...... 307 Study Programme 4-1 A-l/CMTT Coordination of the transmission of sound and picture signals...... 308 Study Programme 4-1B/CMTT Transmission of sound and picture signals by time- division m ultiplex...... 308 Question 5-1/CMTT Transmission of sound programme signals over long distances...... 309 Study Programme 5-1 A-l/CMTT Circuits for high quality monophonic programme trans missions ...... 309 Study Programme 5-1B-1/CMTT Circuits for stereophonic programme transmissions . . 310 Study Programme 5-1 C-l/CMTT Revision of C.C.I.T.T. Recommendation J .2 1 ...... 311 Study Programme 5-1D-1/CMTT Characteristics of signals sent over monophonic and sterepohonic programme circuits ...... 311 Study Programme 5-1E-1/CMTT Compandors for programme circuits...... 312 Study Programme 5-1G/CMTT Transmission of sound programme signals over commu nication-satellite links ...... 313 Question 7/CMTT Automatic measurement and monitoring of television c h a in s ...... 313 Study Programme 7A/CMTT Automatic remote monitoring of test signals in television 314 Study Programme 7B/CMTT Automatic measurement and monitoring on television c h a in s ...... 315 Question 8/CMTT Standard test signal for conventional loading of a television channel . . . 315 “Question 9/CMTT Study of a domestic or regional satellite system for tele communications and sound and television broadcast transmis- ______sion . . __ .317-1 ______There are no Resolutions concerning the work of the CMTT.

OPINIONS Opinion 41 Bandwidths of sound-programme circuits 316 PAGE INTENTIONALLY LEFT BLANK

PAGE LAISSEE EN BLANC INTENTIONNELLEMENT — 15 —

BROADCASTING SERVICE (TELEVISION)

STUDY GROUP 11

Terms o f reference: 1. Study of the technical aspects of the broadcasting service (television), including the use of communication satellites. 2. Study of standards for television recording to facilitate the international exchange of programmes.

Chairman: E. Espin g (Sweden)

Vice-Chairman: M. K r iv o s h e e v (U.S.S.R.)

INTRODUCTION BY THE CHAIRMAN, STUDY GROUP 11

The period 1970-1973 promises an active time for participants in the work of Study Group 11, since in addition to the perennial problems under study, two important new aspects of television technique have been added to the programme of studies. Firstly, the Xllth Plenary Assembly, New Delhi, 1970, decided that all aspects of the recording of television signals, both the video signals and the associated sound channel, whether recorded on film or on magnetic tape, should be transferred from Study Group 10 (sound broadcasting) to Study Group 11. This transfer is reflected in the new terms of reference of the Study Group as given above. These studies are detailed in Questions 16/11-22/11, with associated Study Programmes. This important new field of activity of the Study Group should act as a stimulus to its work and provide useful and interesting problems to solve. Closely associated with the problems of recording and reproduction are those associated with the international exchange of programmes. This is dealt with by Question 2/11 and its associated Study Programme. A second problem that is rapidly growing in importance is the use of communication- satellite techniques for sound broadcasting and television in the new or developing countries, which have particular requirements for educational applications. To this end therefore, Question 5-1/11, with its associated Study Programme, and Questions 23/11 and 24/11 cover a wide range of the various aspects of this significant subject and should be the source of many valuable and interesting contributions. It is to be hoped that some material on this urgent problem will become available in time for the Preparatory Meeting for the World Adminis trative Radio Conference for Space Telecommunications, scheduled to be held in Geneva early in 1971. The use of communication satellites for television broadcasting involves consideration of two possible types of reception: — direct reception, where signals emitted from the satellite are received directly on television receivers, if necessary, suitably modified to deal with the frequency band in use and the low signal level available. In addition the question of suitable antennae for use with these receivers will need to be discussed in order that appropriate recommendations can be made (see Question 7-1/11); — distribution systems, in which the signals from the satellite are received at one, or a number of earth stations, and from thence distributed to the points of reception by conventional television transmitters. — 16 —

It will be an important part of the work of the Study Group to set forth the parameters justifying the application of one or the other of these system. Since an important aspect to be taken into account when making such a decision are the financial and economic implications involved, an Interim Working Party (PLEN/2), under the chairmanship of Mr. B. Y Nerurkar (India), has been set up to study the relative acceptability of different forms of broadcasting using satellites. It is hoped that participants in the work of Study Group 11 will actively assist this Working Party in reaching satisfactory conclusions which would be of interest to the new and developing countries. Whatever may be the final recommendation as to the receiving system to be used, the question of the receivers themselves is of great importance. It is of prime concern that receivers giving an adequate performance at the lowest possible cost should be available. Question 13/11, which deals with this aspect of the problem, should provide valuable technical bases on which the I.T.U. can formulate specifications for suitable receivers. A new and powerful technique in the control of quality of television programmes is the use of special test signals inserted in the field blanking period. The use of such signals enables a continuous check to be maintained on the quality of the emission and by the adaptation of numerical methods of analysis, the results obtained from such checks may be used to correct, automatically, deviations from the required standard almost as they occur. Study Programme 12A/11 and Question 15/11 provide a convenient forum for discussion of these problems. Difficulties associated closely with the quality of television pictures are the need for suppres sing ghost images and the distortion introduced by the use of vestigial sideband modulation. These problems are dealt with in Question 6/11 with its associated Study Programme 6A/11 and in Study Programme 9A/11 respectively. Before one can set up numerical standards for those parameters of the television signal which have a direct impact on the quality of the received picture, it is necessary to have some standard against which this quality can be compared. This is a very complex problem as the assessment of picture quality is highly subjective, depending to a great extent on the individual viewer. Statistical methods are capable of giving a realistic solution to this problem. Questions 3-1/11,14/11 and their associated Study Programmes provide a basis for continuing investigations. An Interim Working Party, under the chairmanship of Mr. T. Kilvington (United Kingdom), was set up by Resolution 58, with the terms of reference “Subjective assessment of the quality of television pictures,” to study this question and to present definite proposals to the XHIth Plenary Assembly. Now that the different systems of colour television have been defined, the subject of conversion from one standard to another remains one of considerable importance. To this end, Study Programme 10A/11 remains active, in order that an internationally accepted system of standard conversion may be achieved. As far as the various standards for colour television are concerned, Question 1/11 and its associated Study Programmes (three new ones were approved by the X llth Plenary Assem bly) remain an active area for investigation as there are still several points to be settled before the whole question of colour television standards can be considered as solved. Finally, since the questions of economical use of the radio-frequency spectrum and the avoidance of harmful interference to other emissions are of great urgency, it is necessary that these problems must be kept under constant study, so that new techniques and advances may best be adapted to serve in improving television services. In consequence, Question 4-1/11 with its associated Study Programme 4-1 A/ll, and Study Programme 12A/11 are maintained. — 17 — Rec. 470, 471

SECTION 11 A: CHARACTERISTICS OF SYSTEMS FOR MONOCHROME AND COLOUR TELEVISION

RECOMMENDATIONS AND REPORTS

Recommendations

RECOMMENDATION 470 *

TELEVISION SYSTEMS The C.C.I.R., (1970)

CONSIDERING (a) that many countries have established satisfactory monochrome television broadcasting services based on either 525-line or 625-line systems; (b) that a number of countries have established (or are in the process of establishing) satisfactory colour television broadcasting services based on the NTSC, PAL or SECAM systems; (c) that it would add further complications to the interchange of programmes to have a greater multiplicity of systems;

UNANIMOUSLY RECOMMENDS 1. that, for a country wishing to initiate monochrome television service, a system using 525 or 625 lines as defined by the C.C.I.R. in Report 308-2 is to be preferred; 2. that, of the systems described in Report 308-2, systems A, C, E and F are not recommended for a new service; 3. that, for monochrome 625-line systems, the video-frequency characteristic described in Recommendation 454 is to be preferred; 4. that, for a country wishing to initiate a colour television service, one of the systems defined in Report 407-1 or any suitable adaption of the NTSC, PAL, or SECAM systems to any one of the monochrome systems defined in Report 308-2 is to be preferred.

RECOMMENDATION 471 / NOMENCLATURE OF COLOUR BAR SIGNALS (Question 1/11) The C.C.I.R., (1970)

CONSIDERING (a) that a number of different colour bar signals used for measurement and adjustment purposes are recorded on magnetic tape, transmitted on national and international circuits or radiated from television transmitters; (b) that the particular signal in use cannot be readily recognized from the video picture-signal waveform;

* This Recommendation cancels Recommendation 212. Rec. 471 — 18 —

UNANIMOUSLY RECOMMENDS 1. that the following nomenclature is used to identify and distinguish between colour bar signals; 1.1 a colour bar generator is assumed to have three outputs corresponding respectively to the red, green and blue primary colour signals; which are then used as input signals to a colour coder. The signal amplitudes enumerated below refer to these coder input signals expressed as a percentage of the white level *, taking this as 100% with the blanking level as zero. During the transmission of colour bars the signal levels should be enumerated in the following order, with an oblique stroke between each number: A — the primary colour signal level during the transmission of the “white” colour bar; B — the primary colour signal level during the transmission of the “black” colour bar; C — the maximum level of the primary colour signal during transmission of “coloured” colour bars; D — the minimum level of the primary colour signal during transmission of “coloured” colour bars.

Example: Referring to Fig. 1, which shows the red primary colour signal for three types of colour bar signal, this data would be expressed as follows: Colour bars (a) 100/0/100/25 Colour bars (b) 100/0/75/0 Colour bars (c) 75/7-5/75/7-5

This nomenclature refers only to the colour bar signal and not to any other signals that may share the raster on a split screen.

* See, for example, Recommendation 451-1, part 2, § 3.3 and Report 308-2, the diagram above Table II. :wie :ylo C yn(uqos) :gen aet prl) :rd :bu B: black BK: blue B: red R: (purple) :magenta M green G: cyan(turquoise) C: yellow Y: whiteW: Signal level relative to peak white (%) Relativeamplitudes colourof bars different typesfor generator of (c) System used NorthAmerica System in (c) 1 — 19 — F gure r u ig Time 1

Rec. 471 Rec. PAGE INTENTIONALLY LEFT BLANK

PAGE LAISSEE EN BLANC INTENTIONNELLEMENT — 21 — Rep. 308-2

11 A: Reports

REPORT 308-2 *

CHARACTERISTICS OF MONOCHROME TELEVISION SYSTEMS

(1951 - 1953 - 1956 - 1959 - 1963 - 1966 - 1970)

The following Tables, given for information purposes, contain details of a number of different monochrome television systems in use at the time of the Xllth Plenary Assembly of the C.C.I.R., New Delhi, 1970.

Frequency (MHz)

F ig u r e 1 Significance of items 11 to 15 of Table I. The numbers in the diagram correspond to those of the items B: channel limits V: vision carrier S: sound carrier

* This Report was adopted unanimously. Rep. 308-2 — 22 — _ 23 — Rep. 308-2 T a b le I — Characteristics of monochrome television systems

System System Item Characteristics Ft}) Et}) At}) A/C) N CO 1 G H 1 D, K, A l (‘) Video characteristics (See also Tables II and III for details of line and field synchronizing signals respectively)

1 Number of lines per picture (frame) 405 525 625 625 625 625 625 625 625 625 819 819 2. Field frequency (fields/second) . . 50 60 50 50 50 50 50 50 50 50 50 50 3 Interlace ...... 2/1 2/1 2/1 2/1 2/1 2/1 2/1 2/1 2/1 2/1 2/1 2/1 4 Picture (frame) frequency (pictures/ second)...... 25 30 25 25 25 25 25 25 ± 0 001 % 25 25 25 25 5 Line-frequency and tolerance when operated non-synchronously (lines/second)...... 10 125 15 750 15 625±0-15% 15 625±0-l % 15 625+01% 15 625 ±01% 15 625 ±0 1% 15 625 ±0 001% 15 625 ±0 05% 15 625±0-l % 20 475 ±0-1% 20 475 6 Aspect ratio (width/height) . . . 4/3 4/3 4/3 4/3 4/3 4/3 4/3 4/3 4/3 4/3 4/3 4/3 7 Scanning sequence . . . (Line) Left to right Left to right Left to right Left to right Left to right Left to right Left to right Left to right Left to right Left to right Left to right Left to right (Field) Top to bottom Top to bottom Top to bottom Top to bottom Top to bottom Top to bottom Top to bottom Top to bottom Top to bottom Top to bottom Top to bottom Top to bottom 8 System capable of operating inde pendently of power supply fre quency ...... Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes 9 Approximate gamma of picture signal...... 0-4-0-5 045 0-45 0-5 0-5 0-5 0-5 0-5 0-5 05 05 06 10 Nominal video bandwidth (MHz) 3 4-2 4-2 5 5 5 5 5-5 6 6 5 10

Radio-frequency characteristics (See also Table IV for ideal sideband characteristics of vision transmitters)

11 Nominal radio-frequency channel bandwidth ( M H z ) ...... 5 6 6 7 7 8 8 8 8 8 7 14 12 Sound carrier relative to vision carrier (M H z )...... - 3-5 + 4-5 4-5 + 5-5 + 5-5 + 5-5 + 5-5 6 + 6-5 + 6-5 + 5-5 ± 11-15 (10) 13 Nearest edge of channel relative to vision carrier (MHz)...... + 1-25 - 1-25 - 1-25 - 1-25 - 1-25 -1-25 - 1-25 - 1-25 - 1-25 - 1-25 - 1-25 ± 2-83 (l0) 14 Nominal width of main sideband ( M H z ) ...... 3 4-2 4-2 5 5 5 5 5-5 6 6 5 10 15 Nominal width of vestigial sideband ( M H z ) ...... 0-75 0-75 0-75 0-75 0-75 0-75 1-25 1-25 0-75 (8) (1-25) 1-25 075 2 16 Minimum attenuation of vestigial sideband (dB) (2) ...... 2 0 ( - 1-25 MHz) 2 0 ( - 1-25 MHz) 2 0 ( - 1-25 MHz) 2 0 ( - 1-25 MHz) 2 0 ( - 1*75 MHz) 20(—3-OOMHz) 2 0 ( - 1-25 MHz) 20 ( - 2 50MHz) (8) 42(—3-58 MHz) 42 (-3-5 MHz) 20(—3-00 MHz) 20(—3-OOMHz) 20(—3-OOMHz) 30(—4-43 MHz) 3 0 O (8) Not defined 30(—4-43 MHz) 30(—4-43 MHz) 30(—4-43 MHz) at —4 43 MHz 17 Type and polarity of vision modula tion ...... A5C positive A5C negative A5C negative A5C negative A5C positive A5C negative A5C negative A5C negative A5C negative A5C positive A5C positive A5C positive 18 Synchronizing level as percentage of peak carrier...... < 3 100 100 100 < 3 100 100 100 100 < 6 < 3 < 3 19 Blanking level as a percentage of peak c a rrie r...... 30 72-5-77-5 72-5-77-5 72-5-77-5 22-5-25-5 72-5-77-5 72-5-77-5 76 72-5-77-5 30 ± 2 22-5-27-5 30 20 Difference between black level and * blanking level as a percentage of peak c a rrie r...... 0 2-875-6-75 2-875-6-75 0-2 3-6 0-2 0-7 0 (Nominal) 3-5 0-7 3-6 5 21 Peak white level as a percentage of peak c a rrie r...... 100 10-15 10-15 10-12-5 100 10-12-5 10-125 20 (Nominal) 10 100 100 100 22 Type of sound modulation .... A3 F3, ± 25 kHz F3, ± 25 kHz F3, ± 50 kHz A3, 50 (as F3, ± 50 kHz F3, ± 50 kHz F3, ± 50 kHz F3, ± 50 kHz A3, no A3, 50 (as A3, no 75 (as 75 (as 50 (as pre-emphasis 50 (as 50 (as 50 (as 50 (as pre-emphasis pre-emphasis pre-emphasis pre-emphasis pre-emphasis pre-emphasis pre-emphasis pre-emphasis pre-emphasis . pre-emphasis 23 Ratio of effective radiated powers of vision and sound (®) .... 4/1 10/1-5/1 10/1-5/1 10/1 (9) 4/1 10/1 (») 5/1-10/1 5/1 2/1-5/1 8/1 4/1 4/1 (4/1) (4)

(*) These systems are given for information only. They are not recommended for adoption by countries setting up a new television service (*) The figures in brackets refer to standard ATI. (see Recommendation 470). (*) The Administrations proposing standards D and K are studying the possibility o f increasing the width o f the vestigial sideband to 1-25 MHz. (*) In some cases, low-power transmitters are operated without vestigial sideband filters. (’) In the neighbourhood o f —fsc (where/sc is the sub-carrier frequency) for transmitters that may transmit colour television signals. T he (*) The values to be considered are: precise values can be determined by further investigations. — the r.m.s. value of the carrier at the peak of the modulation envelope for the vision signal; (•) Applies to Systems D and K only. — the r.m.s. value of the unmodulated carrier for amplitude-modulated and frequency-modulated sound transmissions. (') The Austrian Administration may continue to use a 5/1 power ratio in certain cases where necessary. (*) The figures in brackets refer to the Japanese 525-line system. (10) This System is used both normally and reversed on the frequency scale in a t

T a b le II Details o f line synchronizing signals

Durations (measured between half-amplitude points on the appropriate edges) Durations (measured between half-amplitude points on the appropriate edges) for system for system

Item Characteristics A M N B,H, G (') C I D, K, Kl L F E

•/. h us us %H (ts u* %h US %H us •/.h o us y.H?) us %h us %H us

H Line p e r io d ...... 100 98-8 100 63-5 100 64 100 64 100 64 100 64 100 64 100 64 100 48-84 100 48-84

12-05 a Line blanking interval...... 17-7-19-2 17-5-19 10-24- 16-18 10-2-11-4 16-18 11-52 18-5-19-2 11-8-12-3 18-7 11-8-12-2 ± 0-25 18-5-19-2 11-8-12-3 188 12 0 ± 0 3 18-4 9-9-4 19 92-9-8

b Interval between time datum (Oh) 10-5 and back edge of line blanking 8-96- (mean signal...... 16-2-17-2 16-17 14-16 8-9-10-2 14-16 10-24 16-5 10-2-11 16-1-17-30 10-3-11-3(*) 16-5 value) 16-4 7-8-8-6 17-8 89

c Front porch ...... 2-4 1-28- 1-55 2-3 1-5 ±0-3 2 0 8-1-2 1-2 1-5-20 1-27-2-54 2-4 2-56 2-2-8 1-3-1-8 2-2 1-2-1-6 ± 0 25 2-2-8 1-3-1-8 05-0-7

4-22- d Synchronizing pulse...... 8-1-10-1 8-10 6-6-9 4-19-5-7 6-6-9 7-7-7 4-7 7-3 4-7 ± 0-3 7-2 3-4-3-8 5-2 5-76 45-4-9 7-8 4-8-5-2 ± 0 2 7-7-7 4-5-4-9 2-4-2-6

e Build-up time (10-90%) of the 0-3 edges of the line blanking signal 026-051 0 25-0-5 < 1 < 0 64 < 0 1 < 0 064 0-31-062 02-0-4 0-5 0-2-0-4 ± 0 1 0-31-062 02-04 05 0-3 ± 0-1 04 01-0-3 04 0-17-0 23

f Build-up time (10-90%) of line 03 synchronizing p u ls e s ...... < 0 26 <0-25 < 0 4 < 0-25 <0-4 < 0-256 0-31-062 02-04 0-5 0-2-0-4 ±0-1 0-23-0 46 0-15-03 0-25 0-15 ± 0 05 04 01-0-3 0-25 010-014

(') The primary values are those given in (is. (*) Calculated values. (*) The values given in % H are rounded off. Rep. 308-2 — 26 27 — Rep. 308-2

T ab le III Detail 10y synchronizing signals

System System Item Characteristics A M (») N B , H, G (•) c / D,K,K\ L F E V Field p e rio d ...... (ms) 20 16-667 20 20 20 20 20 20 20 20

H Line p e r io d ...... ([xs) 98-8 63-5 64 64 64 64 64 64 48-84 48-84

j Field-blanking period . . . (p.s) (13-15-5) H (2) (19-21) H + 10-7 (19-25) H (18-22) H + 12 (20-21) H + 12 25 H + U \is 25 H 25 H + 12 p.s (29-30) H + 9 41 H + 18-25 (3) + 10 84

k 0 Build-up times (10-90%) of the edges of field-blanking pulses (jxs) 0-25-0-5 < 6-35 < 6-35 < 6 < 6-4 < 6 02-0-4 0-2-2 < 4-9 < 0 2

/ Duration of first equalizing pulse sequence ...... (4) 3 H 3 H 25 H 2-5 H 2-5 H 2-5 or 3 H 2-5 H 3-5 H

r Nominal interval between begin ning of the field-blanking pulse and the leading edge of the field synchronizing pulse (Ov) .... 3 H

m Duration of synchronizing pulse sequence ...... AH 3 H 3 H 2-5 H 2-5 H 2-5 H 2 5 or 3 H 2 5 H 3-5 H

n Duration of second sequence of equalizing p u lses...... 3 H 3 H 2-5 H 2-5 H 2-5 H 2 5 or 3 H 2-5 H 3-5 H

ps V.H ps ps %H ps ps % H ps %//(•) ps %//(*) ps %H ps %H ps

P Duration of equalizing pulse . . . 3-6-4 2-29-2-54 3-6-4 2-30- 3-4-3-75 2-2-2-4 3-7 2-3-2-5 2-3 3-5-3-85 2-25-2-45 3-7 2-35 ± 0-1 3-5 1-6-18 2-56 ±0-1

q Duration of field synchronizing 27-3 27-3 p u ls e ...... 38-5-42-5 38-42 41-6-44 26-4-28 41-6- 26-52- 42 26-8-27-2 ± 0-2 426 (mean 43 206-21 41 19-21 44 28-16 value)

r Interval between field synchronizing 4-7 pulses...... 11-5-7-5 11-4-7-4 6-8-8 3 8-5 6 6-8-8 3-84- 7-7-7 4-5-4-9 7-8 4-8-5-2 ± 0-2 7-7-7 4-5-4-9 7-3 4-7 ± 0-2 7-2 3-4-3-8 5-63

s Build-up times (10-90%) of the 05 0-2-04 0-3 0-23-0-46 0-15-0 3 025 0-15 ± 0 05 04 0 1-0 3 < 0-4 < 0 2 edges of synchronizing signals . . < 0-26 < 0-25 < 0 4 < 0-25 < 0 4 < 0 25 0-31-0-62 0-2-0-4 ±0-1

(*) Not indicated on diagram. (4) In the 405-line system there are no equalizing pulses; the (ield-blanking period./ commences in advance of the field-synchronizing pulse sequence (*) The coefficient o f H is an integral multiple o f 0-5. by an interval o f from 0 015 H to 0-515 H. (5) In reality, the value of a given in Table II. (*) The primary values are those given in ps. (') The values given in percentages of H are rounded off. Rep. 308-2 — 28 —

T a b l e III A Details of field-synchronizing waveforms 1. Diagrams applicable to all systems except E and M

Note 1. — A A A indicates an unbroken sequence of edges of line-synchronizing pulses throughout the field-blanking period. Note 2. — At the beginning of each first field, the edge of the field-synchronizing pulse (Oy) coincides with the edge of a line-synchronizing pulse if I is an odd number of half-line periods as shown. Note 3. — At the beginning of each second field, the edge of the field-synchronizing pulse (Oy) falls midway between the edges of two line-synchronizing pulses if /is an odd number of half-line periods as shown.

(The durations are measured to the half-amplitude points on the appropriate edges)

F ig u r e l c Details o f equalizing and synchronizing pulses £

— 29 — Rep. 308-2

T a b l e III B Details of field-synchronizing waveforms 2. Diagrams applicable to system E

See Figure 2c Signal at beginning of each first field

See Figure 2c Signal at beginning of each second field

Note 1. — A A A indicates an unbroken sequence of edges of line-synchronizing pulses throughout the field-blanking period. Note 2. — At the beginning of each first field, the edge of the field-synchronizing pulse (Ov) coincides with the edge of a line-synchronizing pulse. Note 3. — At the beginning of each second field, the edge of the field-synchronizing pulse (Ov) falls midway between the edges of two line-synchronizing pulses.

• Blanking level

■Sync, level

(The durations are measured to the half-amplitude points on the appropriate edges)

F ig u r e 2 c Details of equalizing and synchronizing pulses Rep. 308-2 — 30 —

T a b l e III C Diagrams applicable to system M

F i g u r e 3a Signal at beginning of each first field

F ig u r e 3 b Signal at beginning of each second field

Note 1. — A indicates an unbroken sequence of edges of line-synchronizing pulses throughout the field-blanking period. Note 2. — Field-one line numbers start with the first equalizing pulse in Field 1, designated 0 Ei in Fig. 3a. Note 3. — Field-two line numbers start with the second equalizing pulse in Field 2, one-half-line period after 0 E2 in Fig. 3b. — 31 — Rep. 308-2

Blanking level

Sync, level

F ig u r e 3 c Details of equalizing and synchronizing pulses

(The durations listed in Table III relate to the half-amplitude points on the appropriate edges) Rep. 308-2 — 32 —

T a b l e IV Ideal amplitude-frequency characteristics for vision transmitters (See Table I for precise frequency spacings)

BS B S A 11 1 1 II 11

B SB M,N - SB B,C ------II

S' B S B G i i i i 1

S’ B s B H i i i i

<>' B . B I

SB SB D,K II 1 1 ||

SB SB K1.L 1 1 1 ■ II

SB SB F II 1 1 ■ 1

S B j>B E | II | -4 -2 0 2 4 6 8 10 12

System-frequency (MHz) relative to the vision carrier frequency

S : sound carrier S': sound carrier of the lower adjacent channel (upper channel in system A) B : nominal limits of channel — 33 — Rep. 308-2

ANNEX

SYSTEMS USED IN VARIOUS COUNTRIES

Explanation of signs used in the list: *: planned (whether the standard is indicated or not); —: not yet planned, or no information received.

NOTES TO LIST

Note 1. — Austria reserves the right to the possible use of additional frequency-modulated sound carriers, in the band between 5-75 and 6-75 MHz, in relation to the picture carrier.

Note 2. — The Indications and Notes are based on indications and notes given in Chapter 2 of the “Technical data used by the European VHF/UHF Broadcasting Conference” .

Note 3. — No definite decision has been taken about the width of the residual sideband, but this country is willing to accept the assumption that for planning purposes the residual sideband will be 0-75 MHz wide.

Note 4. — System I will be used at all stations. In addition, during a transition period, trans missions on system A will be made from the Dublin and Sligo stations.

Note 5. — This country does not at present intend to use bands IV and V, but accepts the parameters given in the table under “ Standard G ” as television standard in bands IV and V.

Note 6:— No final decision has been taken about the width of the residual sideband, but for planning purposes this country is willing to accept the assumption of a residual sideband 1-25 MHz wide.

Note 7. — The Swiss Administration is planning to use additional frequency-modulated sound carriers, in the frequency interval between the spacings of 5-5 and 6-5 MHz in relation to the picture carrier, at levels lower than or equal to the normal level of the sound carrier, for additional sound-tracks or for sound broadcasting.

Note 8. — Liberia accepted for planning purposes Standard B or H but reserves the right to adopt standard M.

Note 9. — Uganda is already committed to Standard B in band III. Standard G is planned for bands IV and V although further consideration will be given to other standards when bands IV and V stations are to be commissioned.

Note 10. — Indications for Malawi, Rhodesia and Zambia are based on indications foT Rhodesia and Nyasaland (Federation of) given in the Final Acts of the African VHF/UHF Broadcasting Conference, Geneva, 1963. Standard B is now in use in band I; no final decision is taken regarding systems to be used in bands III, IV and V. Rep. 308-2 — 34 —

Note 11. — Sierra Leone now uses Standard B but reserves the right to use any other standard compatible with the Plan.

Note 12. — Tanzania, the indications are based on indications for Tanganyika and Zanzibar given in the Final Acts of the African VHF/UHF Broadcasting Conference, Geneva, 1963. It is intended to use Standard B in bands I and III. Although Standard I is planned for bands IV and V, further consideration will be given to the use of Standards G and H.

Note 13. — Algeria reserves the right to change later.

Note 14. — United Arab Republic is now studying the adoption of either Standard G or H for bands IV and V.

Note 15. — Cameroon, Congo (D. R. of) and Guinea, planning has been based on Standard Kl, but they reserve the right to use any other standard compatible with the Plan when they introduce television.

Note 16. — The indications and Notes 10-17 are based on indications and Notes given in the Final Acts of the VHF/UHF African Broadcasting Conference, Geneva, 1963.

System used in bands: Number of Note for bands: Country I-III IV-V I-III IV-V

British East Africa B * Algeria (Algerian Democratic and Popular Republic) B, E G *, H * 13, 16 13, 16 Netherlands Antilles M — Saudi Arabia (Kingdom of) M — Argentine Republic N N* - Australia (Commonwealth of) B — Austria B G * 1 Belgium C, F H* People’s Republic of Bulgaria D K* Burundi (Republic of) Kl * Kl * 16 16 Cameroon (Federal Republic of) Kl * Kl * 15, 16 15, 16 Canada M M Central African Republic Kl * Kl * 16 16 Cyprus (Republic of) — H * 2 Congo (Democratic Republic of the) Kl * Kl * 15, 16 15, 16 Congo (Republic of the) (Brazzaville) Kl * Kl * 16 16 Korea (Republic of) M — Ivory Coast (Republic of the) Kl * Kl * 16 16 Dahomey (Republic of) Kl * Kl * 16 16 Denmark B G * 3 Spain B G * 2 United States of America M M Ethiopia B * G * 16 16 Finland B G* 3 France E L Gabon Republic Kl * Kl * 16 16 Ghana B *, G * G * 16 16 Greece B * G * 3 Guinea (Republic of) Kl * Kl * 15, 16 15, 16 Upper Volta (Republic of) Kl * Kl'* 16 16 Hungarian People’s Republic D K* India (Republic of) B — Indonesia (Republic of) B * — Iran M — — 35 — Rep. 308-2

System used in bands: Number of Note for bands: Country I-III IV-V I-III IV-V Ireland A, I I* 4 Iceland — G * 2, 5 Israel (State of) B * H * 6 Italy B G Japan M M * Jordan — — Kenya B * G*, I* 16 16 Liberia (Republic of) B * H* 8, 16 8, 16 Libyan Arab Republic B * G * 16 16 Luxembourg F H* 2 Malaysia B G * Malawi B * G * 10, 16 10, 16 Malagasy Republic Kl * Kl * 16 16 Mali (Republic of) Kl * Kl * 16 16 Morocco (Kingdom of) B H * Mauritania (Islamic Republic of) Kl * Kl * 16 16 Mexico M — Monaco E L* Niger (Republic of the) Kl * Kl * 16 16 Nigeria (Federal Republic of) B I* " 16 16 Norway B G * . 3 New Zealand B — Uganda B G * 9, 16 9, 16 Pakistan B — Panama M — The Netherlands (Kingdom of) B G 3 People’s Republic of Poland D K* Portugal B G * Spanish Provinces in Africa B * G* 16 16 Portuguese Oversea Provinces I* I* 16 16 United Arab Republic B G *, H * 16 14, 16 Federal Republic of Germany B G Somali Republic B * G * 16 16 Rhodesia B G * 10 10 Roumanian Socialist Republic D K* 2 United Kingdom A I Rwanda (Republic of) Kl * Kl * 16 16 Senegal (Republic of the) Kl * Kl * 16 16 Sierra Leone B G * 11, 16 16 South Africa (Republic of) I* I* 16 16 Sweden B G * 2, 3 Switzerland (Confederation of) B G * 2, 7 Tanzania (United Republic of) B *, I * I* 12, 16 12, 16 Chad (Republic of the) Kl * Kl * 16 16 Czechoslovak S.R. D K * 2 Oversea Territories in Africa for the international relations of which the Government of the United King dom of Great Britain and Northern Ireland are responsible B *, I * I* 16 16 Oversea Territories of the United Kingdom in the European Broad casting Area — H * 2 Togolese Republic Kl * Kl * 16 16 Turkey — H * 2, 6 U.S.S.R. D K Uruguay (Oriental Republic of) N — Venezuela (Republic of) M — Yugoslavia (Federal Socialist Republic of) B G Zambia (Republic of) B * G * 10, 16 10, 16 Rep. 312-2 — 36 —

REPORT 312-2 *

CONSTITUTION OF A SYSTEM OF STEREOSCOPIC TELEVISION (Study Programme 1C/11)

(1963 - 1966 - 1970)

1. Methods of providing stereoscopic television have long been the subject of study in various countries. Some of these studies were made with mechanical scanning systems, ante-dating the electronic systems now in use. Several methods have been proposed to ensure that each of the two reproduced stereoscopic images reaches the proper eye of the viewer, and many of the methods are applicable to all electronic systems. The first method was based directly on the optical stereoscope and consisted of the repro duction of two spatially separated images, one for each eye. The larger separations, to accommodate larger images, prismatic viewing devices or prismatic spectacles, could be used to produce visual registration of the two images. A second method consisted in the production of two overlapping images in complementary colours and the use of complementary colour filters, sometimes in spectacles worn by the observer, to separate the two images. A third method provides overlapping images, produced by light which is polarized in orthogonal planes for the two*images, together with the use of spectacles with polarizing filters. Several methods of separating the two pictures, without the use of spectacles, have been devised. These make use of gratings or lenticular screens. Both gratings and lenticular optical systems have been applied to cathode-ray receiver displays. These methods may have more serious limitations as to permissible viewing positions than do methods employing spectacles.

2. The transmission of a stereoscopic television signal requires the simultaneous or successive transmission of several separate signals. Methods have been suggested for reducing the bandwidth required. This question has many aspects in common with colour television and the use of the transmission methods, of which study has been made for colour television, may be envisaged for stereoscopic television transmission.

3. Various solutions for reproducing the stereoscopic picture have been envisaged. Some of these solutions entail the use, for the reproduction of a stereoscopic monochrome or colour picture, of television sets designed for the reception of normal non-stereoscopic pictures.

4. Further studies should be carried out and it should be borne in mind that the problems of bandwidth and compatibility with monochrome and colour systems are of. great importance.

5. Doc. XI/22, Moscow, 1958; Doc. XI/20 and Doc. XI/34, Bad Kreuznach, 1962; Doc. XI/65 and Doc. XI/66, 1963-1966, and Doc. XI/42 (U.S.S.R.), 1966-1969 and their bibliographies, contain some information on the question of stereoscopic television. ,

* This Report was adopted unanimously. — 37 — Rep. 406

REPORT 406 *

COLOUR TELEVISION

(1966)

1. C.C.I.R. Study Group XI met in Vienna in March-April 1965 under the chairmanship of Mr. Esping, to consider the choice of a colour television system for use in the European Broadcasting Area and in other countries, using one of the 625-line television standards (Reference: Question 1/XI, Study Programmes 1A/XI and 1B/XI, Report 309).

2. Three possible colour television systems were considered by the Study Group namely: NTSC (625 lines), PAL, SECAM III. The detailed parameters of the systems considered are to be found in C.C.I.R. Doc. XI/33, 1963-1966.

3. It was agreed that the three systems satisfied the three basic conditions listed in Report 309 as being “generally considered desirable” , namely: / — colour and monochrome systems should be compatible; — the signal should be composed of a luminance signal and two signals carrying the colour information, in so far as possible in accordance with the constant luminance principle; — the chrominance signal should share the luminance frequency band.

4. In considering the technical factors listed in Question 1/XI, the Study Group had before it the documents listed in Annex III.

5. In particular, the Study Group took note of the very extensive laboratory and field tests carried out by broadcasting authorities, Administrations and industrial organizations in a number of countries, the results of which, up to February 1965, were summarized by the E.B.U. in C.C.I.R. Doc. XI/33, 1963-1966.

6. The Study Group reached the following conclusions in relation to the technical factors listed in Question 1/XI:

6.1 Satisfactory picture (colour and monochrome) and sound quality The three colour systems are all capable of producing colour pictures of satisfactory definition and colour rendering under good transmission and reception conditions. However, it should be noted that the overall tolerances for achieving these conditions are different for the various systems (see §§ 6.4 and 6.5). Some differences also exist in colour resolution of the systems, nevertheless divergent opinions have been expressed as to their importance (see Docs. XI/33, XI/40, XI/46 and XI/77, 1963-1966). The sound quality is identical with that obtainable on the equivalent monochrome system.

6.2 Economical use o f bandwidth The three colour systems require no additional bandwidth as compared with an equivalent monochrome system.

6.3 Reliable receivers at reasonable cost Annex I gives estimates of receiver cost, collected from various sources and it refers to basic manufacturing cost.

* This Report was adopted unanimously. Rep. 406 — 38 —

In an NTSC or simple PAL receiver, a hue control and a saturation control are available and necessary. In the delay-line PAL receivers, a saturation control is necessary. In the SECAM III receiver, neither of these controls is essential, but they may be added if desired (see Docs. XI/33, p. 12, § 2.2.2 and XI/35, 1963-1966).

6.4 Operation

Annex II contains a comparison.between the present performance of the transmission chain and the overall tolerances.

6.4.1 Studio equipment

All types of colour cameras and film scanners are suitable for use with any of the systems; the differences between the colour systems liejn the coding equipment, the vision fading and mixing equipment, and video-tape recording equipment. No special difficulties are foreseen with regard to the basic unit (comprising ten distribution amplifiers, two studio mixers and a short link, a few kilometres long, which may be either a coaxial cable or a single-hop radio link), because distribution amplifiers can be made with high precision, as can a short link. Difficulties with regard to the mixer used with the SECAM III system can be overcome by suitable design, at the expense of a reduction of luminance bandwidth to about 3 MHz for the duration of the mix and/or special effects. The effect of this reduction of bandwidth may be partially compensated by the use of crispening techniques. The magnetic recording of NTSC signals requires a full complement of auxiliary equipment such as automatic timing control devices (see Doc. XI/47, 1963-1966). Furthermore, higher recording carrier frequencies may be required than those used in 625-line monochrome practice. Experience in existing colour television services has shown that the main defects of NTSC magnetic recordings are caused by colour banding and differential phase. Experiments made with a new machine of the latest type has shown that, with good adjustments, the pictures obtained are generally satisfactory; the remaining defect is that of colour banding which is mainly noticeable on certain saturated colours (orange, yellow, red). When recording PAL signals with the same equipment as used for the recording of the NTSC signals, the pictures obtained are better than with the NTSC system. The magnetic recording of SECAM III signals presents no problem, in that normal good quality black-and-white video-tape recording machines can be used without modification. Furthermore, the picture quality obtained from a SECAM III recording has been judged to be better than that of PAL and NTSC pictures. As regards source-noise in the three colour channels, the SECAM III system is slightly more sensitive than NTSC and PAL (see Docs. XI/33, p. 10 and XI/57, 1963- 1966).

6.4.2 Relaying equipment

Microwave-relay and cable links for the transmission of colour signals from point-to-point require a very high standard of performance in respect of differential gain and differentia] phase, if they are to be suitable for the NTSC system. Such circuits have been constructed and operated under practical conditions, over distances greater than 4800 km, using Standard M, which requires a nominal bandwidth of — 39 — Rep. 406

4-2 MHz (see Doc. 4, London, 1964 and Doc. XI/68, 1963-1966). A substantially lower standard of performance cpuld be accepted for SECAM III and PAL (delay- line receiver) in respect of differential phase. As regards differential gain, SECAM III has an advantage. If asymmetric sideband distortion occurs in the chrominance signal channel during transmissions on some long-distance cable links, the PAL system shows advantages. Some existing long-distance circuits will require a substantial improvement, in particular as regards the amplitude/frequency response and signal-to-noise ratio, whatever colour system be adopted.

Note concerning §§ 6.4.1 and 6.4.2: The colour system used in this equipment need not necessarily be the same as that used for transmitting equipment (§ 6.4.3), because transcoders for several systems have been shown to be feasible. A new corrector for differential phase and gain, based upon three sub carrier pilot bursts at black, grey and white levels inserted into the line-blanking interval, can be used to reduce the figures for differentia] gain and phase by factors of twice and three times respectively.

6.4.3 Transmitting equipment

All transmitters could be notified so as to make them adequately free from distortion for any of the three systems. Difficulties are likely to be experienced in obtaining a suitable amplitude/frequency response with C.C.I.R. Standard G at the upper end of the video channel; this will mainly affect the NTSC system. It is believed that an adequate response and adequate stability can be obtained for the NTSC system but there may be additional complexity and maintenance problems, compared with SECAM III and PAL. For all systems it is necessary to standardize the group-delay time difference between the modulated luminance signal and the modulated chrominance signal. For economic reasons, it is furthermore desirable to correct in the transmitters for the group-delay errors of an average receiver. Doc. XI/155, 1963-1966, contains a proposal for such a correction for standards B, G. Doc. XI/178,1963-1966, contains information of such a correction for standard L. Transposers of modern design, which perform the frequency-changing operation on the vision and sound signal in one operation, generally have adequate linearity for dealing with any of the three colour systems. With the transposers having separate conversion of sound and vision, the prob lems are similar to those of transmitters. For all the colour systems, it may be necessary to limit the power output of existing transposers designed for black-and-white opera tion, so as to achieve the linearity necessary to avoid the reintroduction of the unwanted sideband. Differential phase requirements, particularly in the case of NTSC, will also restrict the power output. It is not known which of these effects will be the limiting factor. Experiments with the three systems have shown that three transposers may be used in tandem without deleterious effects due to the equipment being observed.

6.5 Susceptibility to interference Colour television signals are sensitive to CW interference at frequencies in the region of the vision carrier, in the same way as monochrome signals; in addition, they are more sensitive to interference at frequencies within the chrominance band. In general, however, there is little difference between the susceptibilities of the three systems to CW interference of uncontrolled frequency. Rep. 406 — 40 —

Under conditions of multipath reception, where the received picture is on average of fairly good quality, the PAL system shows a slight advantage. This slight advantage is also present for the SECAM III system, provided there is adequate field strength at the receiving site (see Docs. XI/33 and XI/51, 1963-1966). For signal-to-noise ratios corresponding to a picture quality ranging between excellent and poor, the sensitivity of the three systems to random noise is appreciably the same. However,' within this range of picture quality, the advantage of NTSC and PAL varies from 1 to 2 dB. But if this ratio deteriorates so as to give pictures of poor or very poor quality, SECAM III is 3 dB more sensitive to noise than NTSC and PAL.

6.6 Compatibility When a colour signal is displayed on a monochrome receiver, the chrominance signal gives rise to visible effects on the reproduced picture. These effects are regular patterns in coloured areas for NTSC and PAL and irregular patterns all over the picture in the case of SECAM III. The assessments of observations made on picture monitors using Standards G, I and L have shown that the compatibility of NTSC is “slightly better” to “better” than that of the other systems. PAL has a slight advantage over SECAM III. Further results show the assessments made during observations on domestic receivers. In these results, the most favourable assessment is for NTSC and, from observations made on Standard /, the percentage of assessments having a grade greater than 3-5 A (see Annex II, Remarks) is noticeably less than that for either of the other two systems for very saturated camera pictures viewed under the conditions laid down by the ad hoc Group of the E.B.U. The average absolute assessments for SECAM III and PAL are equal. Observations made on Standard G and using domestic receivers show that on average PAL is “very slightly worse” than NTSC (see Doc. XI/33, 1963-1966). More recent tests (see Doc. XI/53, 1963-1966) show that under normal receiving conditions NTSC and PAL were found to be practically equal. SECAM III was found to be slightly worse than NTSC and PAL. Tests conducted with domestic receivers on Standard L have shown that when, due to random noise, the picture quality is between good and fairly good, the compatibilities of the three systems are practically the same (see Doc. X I/59,1963-1966). Tests made with domestic receivers on Standard K in normal reception conditions showed that there was no difference between the NTSC and SECAM III systems. The majority of the test pictures came from slides (see Doc. XI/44, 1963-1966). The system for which a colour receiver is designed does not affect its ability to reproduce monochrome signals in monochrome.

6.7 Frequency planning

The main consideration in frequency planning is the susceptibility of the wanted signal to co-channel interference. The planning standards already adopted in UHF for monochrome are considered satisfactory for colour. When the frequency stabilities of the wanted and interfering signals are adequate for advantage to be taken of the offsetting and when the interfering carrier falls within the chrominance band, the NTSC and PAL systems are better. If these conditions are not achieved the SECAM III system is on the average as good as the NTSC system. Problems in connection with coverage are mentioned under §§ 6.5, 6.10 and 6.11.

6.8 International exchange o f programmes Programmes may be exchanged between countries having the same scanning standards by direct relay (see § 6.4.2) and by means of video-tape recording (see § 6.4.1); or by means — 41 — Rep. 406

of film recordings which may be used whatever, the scanning standards. In the latter case, there are no experimental data available at present to the C.C.I.R. that would define object ively the picture quality that could be obtained. Nevertheless, the experts of certain countries consider that the various systems may yield different picture qualities, particularly with regard to vertical resolution (see § 6.1) and other characteristics. For exchanges between countries using the 625-line standard with different video bandwidths (e.g. 5, 5-5 or 6 MHz) by means of direct relay or video-tape recording, problems arising from the different bandwidths are not serious whichever colour system is used. As to programme exchange by line, however, the PAL system, using a delay line, offers some advantages, especially for Standard G, insofar as limiting of the chrominance band does not affect colour crosstalk. A special problem exists for programme exchanges between countries using the 525- line and 625-line standards. Direct broadcasting without signal processing of signals on one standard for reception by receivers designed for the other, is not envisaged. In all cases, programme exchange requires a transformation by a broadcasting organization of the signal received, to adapt it for broadcasting over the national network. This transformation requires special electronic equipment. 6.8.1 If the conversion is done by simple translation of the frequency of the chrominance signal, the resulting colour-television signal differs in number of lines and in field frequency from the normal signal used in the country in question. This solution requires a decision about the adoption of dual-standard television in the country concerned. It is probable, from a theoretical standpoint, that the translation could be done with a loss of luminance information which is slightly less for NTSC than that obtained for the other systems, although the amount of this loss is not adequately known. With the same restrictions, it is possible that PAL is a little better than SECAM III and very close to NTSC. 6.8.2 If the conversion is to result in a signal conforming to the system of the receiving country, the difficulty of the conversion increases and it is probable that the differences between the colour systems are reduced (see Docs. XI/33, XI/48 and XI/49, 1963-1966, and Doc. 10, London, 1964).

6.9 Scope for development As far as future prospects are concerned, it can be said that the NTSC system seems more easily adaptable to the single-gun tube. The PAL system is a little less adaptable and the SECAM III system is still less adaptable. Further work is still needed. The NTSC system preserves the vertical resolution, in colour, to a greater extent than does the SECAM III system with the PAL system as intermediate. The PAL and, above all, the SECAM III systems will permit video-tape recording more easily.

6.10 Differences between bands I and III compared with bands IV and V Experience indicates that multipath propagation effects are less serious in bands IV and V because much better antenna directivity can be obtained than in bands I and III (see Doc. 23, London, 1964).

6.11 Effects due to the simultaneous presence o f several different types o f distortion A certain number of results have been obtained concerning the effects of a simultaneous combination of distortions (see Docs. XI/12, XI/33, XI/34, XI/51, XI/56, X I/67,1963-1966). For certain distortion combinations, consisting of differential gain and/or unwanted attenuation of the chrominance signal, for which noise occurs at a high level, the SECAM III system has proved to be more sensitive than the NTSC or PAL systems. Rep. 406 — 42 —

With other combinations, especially when a high degree of non-linear distortion is present, the SECAM III system has proved to be less sensitive than NTSC.

ANNEX I

COST AND PERFORMANCE OF THE COLOUR RECEIVER

1. Introduction

1.1 The basis of cost comparison was a table-type receiver in a wooden cabinet, generally similar to the RCA-CTC 15. 1.2 The price of the receiver was calculated as the cost ex-works, inclusive of all works charges and of packing in a corrugated cardboard box; no provision was made for any distributor’s costs, sales or other taxes, etc. 1.3 The basic NTSC receiver was assumed to be valve operated. The costs of additional circuits for the other systems were calculated on the basis of valve or transistor circuits as judged most advantageous by the manufacturers concerned. 1.4 The cost figures have been put forward on the basis of existing designs, and used for the most part during the tests. Improvements in design due to the use of transistors or other circuit improvements could possibly apply to all types of receiver. 1.5 The cost comparison was based on a quantity of a hundred thousand receivers per annum per country. 1.6 In the cost calculations, no provision was made for patent royalties. 2. As a result of discussions, the values set out in the Table were established. These values are subject to the following notes: 2.1 The cost of the delay-line is as stated in the headings of the columns, but the cost of the crystal for the NTSC system is considered as varying between $ 1 and $ 1.50. 2.2 The performance of a steel delay-line costing 14 French francs has proved satisfactory in the SECAM III receiver. The performance of a glass delay-line costing 20 DM has proved satisfactory in the PAL receiver. 2.3 All manufacturers (subject to § 2.8 regarding the Netherlands) used the same basis as regards circuit technique for the cost calculation of the NTSC receiver. In receivers for the SECAM III and PAL systems, the costs have been based on the circuit realization which manufacturers in each country considered appropriate. This may explain some of the variations in the values given in columns 3 and 4, and the consequent variations in other columns. 2.4 The entries given in the Table are the result of study by the principal manufacturers in the countries concerned. 2.5 The NTSC receivers taken into consideration for the Table did not include automatic gain control in the chrominance circuit. The additional cost of this control would be approxi mately 0-3%. Some manufacturers, however, do not consider the addition of this control to be necessary. 2.6 The vision channel a.g.c. normally used in a colour receiver is considered satisfactory for a SECAM III receiver, but if separate luminance and saturation controls are desirable, their inclusion would have no appreciable effect on the cost of the receiver. 2.7 The German representatives considered that a new design of the PAL receiver does not require a sub-carrier crystal and that the omission of this component would reduce the price of the PAL receiver by 0-73 %. 2.8 The figures submitted by the Netherlands refer to existing receivers of comparable perform ance on all three systems, although their reference NTSC receiver has a performance some what better than the CTC 15. In their judgement, the figures submitted by the Netherlands representatives most clearly represent the position. However, figures relative to the reference NTSC type CTC 15 receiver would be, in columns 5 and 6, values of 7-3 and 8 0 respectively. — 43 — Rep. 406

2.9 The chrominance chassis for SECAM III type PVL 2 uses the luminance channel for the amplification of the chrominance signals, which allows the separation at a high level with a consequent simplification of the circuit. In this case, the differences between the NTSC and SECAM III receivers are not due solely to the chrominance decoder, but to the combi nation of the chrominance and luminance circuits, after the output of the detector and be fore the input to the matrix circuits.

T a ble

Cost data on colour receivers relative to the costs of an NTSC receiver (Type RCA-CTC 15, see §§ 1.1 and 2.8)

Delay-line at

20 DM NTSC $5 14 F. fs. chroma approx. $5 v^ouniry V.pcrcciii<4gc ui total cost) Relative cost of chroma Percentage additional cost circuit relative to NTSC relative to NTSC total cost

SECAM III PAL SECAM III PAL (i) (2) (3) (4) (5) (6)

France 4-88 1-38 — -0-35 0 —

Italy 50 1-72 (3) 2-3 3-6 (3)

Netherlands 50 2-0 2-15 5 (2) 5-7

Germany (Federal 4-5 (3) Republic of) 65 1-7 1-7 (3) 30

United Kingdom 4-2 1-41 1-83 M 0 3-5

C) These figures relate to recent receivers (end of 1964). The sign (—), which indicates an advantage for the SECAM system, concerns a PVL 2 receiver, which did not participate in the demonstrations described in Doc. XI/46, 1963-1966, except for a single set, which was not subjected to the tests described in Docs. XI/58 and XI/33, 1963-1966. (2) This relative cost is not based on the cost of a delay-line of 14 French frs., but of 20 DM. (3) Following recent developments, Doc. XI/78, 1963-1966, new designs will enable a considerable reduction to be made in the cost of PAL receivers. However, the receivers of this type were not subjected to the tests described in Doc. XI/33, 1963-1966. An initial assessment for Italy would be 1 -90 % instead of 3-60 % and for the Federal Republic of Germany 2-5 % instead of 4-5 %. ANNEX II

COMPARISON BETWEEN THE PRESENT PERFORMANCE OF THE TRANSMISSION CHAIN AND THE OVERALL TOLERANCES FOR PICTURE GRADES 2'5 A AND 3'5 A

Centre, or null output, frequency of receiver Group-delay of the Chrominance signal References chrominance Level-dependent Ratio of the amplitude Level-dependent chrominance signal (Doc. XI/33, Individual performance discriminator and phase errors phase of the of the chrominance amplitude of the with respect to that Vienna, figures centre frequency independent signal to that chrominance signal of the luminance signal; of luminance signal chrominance signal 1965) of coder frequency (differential phase) of the luminance signal (differential gain) (2) tolerance at frequency modulator magnitude (dB) (%) of sub-carrier (kHz) (ns)

O §3.4 Receiver ± 5 0 ± 5 10 ?

7 O §3.3 Transmitter ± 5 ± 1 1 0 with pre-corrector

§ 3.2.1 Distribution net ± 1 0 ° (9) ± 2 8 25 work (3) D §3.1.1 Studio centre ? ± 3 ? 5 ± 10 “basic unit” 0(4) §3.1.2 Tape recorder - o ± 5° O ± 4 ? 2 0 ?

Arithmetic sum (5) 7 ± 27° 7 35 ? Quadratic sum (5) ± 13° ? 17 7

Overall tolerances Grade Grade Grade Grade Grade Grade (*), (7), (8) 2-5 A 3-5/4 2-5 A 3-5/4 2-5/4 3-5/4 2-5/4 3-5/4 2-5/4 3-5/4 2-5.4 3-5/4

§2.4 NTSC — — ± 1 2 ° ± 15° ± 1 2 ° ± 2 0 ° ±2-5 ± 4 30 40 + 2 0 0 + 350 Table II - 300 - 500

SECAM III + 12 ± 30 — — ± 40° ± 50° ±2-5 ± 4 65 70 + 2 0 0 + 450 - 23 - 300 - 500

PALd, PALn — — ± 40° ± 50° ± 40° ± 50° ±2-5 ± 4 30 40 + 2 0 0 + 350 - 300 - 500

PALS --- — ± 12 ° ± 15° ± 1 2 ° ± 2 0 ° ± 2-5 ± 4 30 40 + 2 0 0 + 350 - 300 - 500 — Considered to be unimportant or of negligible-value or easily adjustable or irrelevant. ? Insufficient information available.. - C1) Applies to SECAM III only. (2) 100 (1 — m \M ) where m is the minimum amplitude of the chrominance signal and M is its maximum value. Although this formula always gives results which are positive, some compensa tion is possible when sev.eral pieces of equipment are connected in tandem. (3) For a video section. '"The figures of the Table-are not applicable to a more complex network composed of several “video to video” sections in cascade. (4) These figures represent the best results obtainable at present on a new-model machine. It is assumed that further improvements will be such that these figures will correspond to performance in normal operating conditions. (5) It,is not known how the distortions indicated by the figures in any one column of the Table will add in practice. Two examples (arithmetic and quadratic) of additions are given. (°) It is also not known what the effect upon the overall tolerances would be when more than one distortion giving rise to the same grade of picture impairment exists simultaneously. Recent tests-with NTSC have shown, however, that the simultaneous presence of differential gain and differential phase each giving, alone, an impairment of grade 3-5,4 results in an impairment of grade 4-1,4. The result for single impairments of grade 2-5 A is grade 3-1.4. In order that, with the two distortions simultaneously present, the grading shall be either 3-5.4 or 2-5/1, the repsect- ive overall tolerances may be multiplied by approximately 0-8. The probability of the simultaneous presence of the two distortions at overall tolerance values is not, known. (’) The overall tolerances are intended to apply to those parts of the colour television transmission chain between and including both coder and decoder. (8) The gradings of picture .quality correspond to the Table below:

Absolute grades (A)

(a) Impairment I A: Imperceptible 4A: Somewhat objectionable 2A : Just perceptible 5 A : Definitely objectionable 3A : Definitely perceptible, but not disturbing 6A: Unusable

(b) Quality 1A: Excellent ' 4 A Rather poor . 2 A : Good 5A: Poor 3A: Fairly good 6A: Very poor

(•) Experience in the U.S.A. is given in Doc. 4 (Rev.), London, 1964, and indicates that the corresponding figure for a network comprising more than one video-to-video section is 4-5°, which includes 96 % of the measured samples. Rep. 406 — 46 —

ANNEX III

LIST OF DOCUMENTS CONCERNING QUESTION 1/XI COLOUR TELEVISION STANDARDS

Doc. XI 1963-1966 Submitted by Title 1. London, 1964: Colour Sub-Group of Study Group XI

Japan Separate luminance colour television system. Standards for video colour television signals. 2 United States of America Survey of colour television receivers. 3 United States of America A summary of practical experience with colour television in the United States. 4 and United States of America Differential gain and phase measurements on long Rev. distance television transmission circuits. 5 Federal Republic of Germany Colour television standards. Standards for an experi mental 625-line, 5 MHz colour television system of the NTSC type. Federal Republic of Germany Colour television standards. Standards for an experi mental 625-line, 5 MHz colour television system of the PAL type. E.B.U. Colour television standards. Report of the E.B.U. ad hoc Group on Colour Television. United Kingdom Comparison of colour systems. 9 United Kingdom Separate and constant luminance. 10 Netherlands On the choice of sub-carrier-, line- and field-frequencies for a European colour television system. 11 Netherlands On the use of a line-time delay line in a decoder for the NTSC system. 12 Netherlands Some experiments on the performance of the PAL colour television system. 13 Netherlands Delay-line tolerance in the PAL-decoder. 14 United States of America Colour errors in colour television cameras using the NTSC system. 15 E.B.U. Colour television standards. 16 France Colour television standards—SECAM system. 17 U.S.S.R. Study of the influence of variations in signal levels in colour television systems. 18 U.S.S.R. Influence of the accuracy of establishment of phase rela tions in colour television systems with modulation of the sub-carrier in quadrature. 23 E.B.U. Comparative field trials of three colour television systems in shadow areas. 24 France Quality of compatible black-and-white pictures in colour television systems NTSC, SECAM III and PAL. 29 Chairman, Colour Questionnaire by the Chairman of the Colour Sub-Group Sub-Group, S.G. XI of Study Group XI. 32 United Kingdom Compatibility with camera pictures and domestic receivers. 33 Colour Sub-Group, S.G. XI Report of Study Group XI, Colour Sub-Group. 33 (1st Rev.) and Corr. 1 33 (2nd Rev.) 34 and C.C.I.R. Answers to the Questionnaire in Doc. 29. Corr. 1 — 47 — Rep. 406

Doc. XI 1963-1966 Submitted by Title

2. Interim Meeting of Study Group XI, Vienna 1965

1 C.C.I.R. Final Report of Study Group XI Colour Sub-Group (London, Doc. 33 (2nd Rev.)). 12 United States of America Relationship of aural to visual received powers—New York City UHF television project. 26 O.I.R.T. Investigation of compatibility of the SECAM colour television system. 29 United States of America Comparison of the receivers for NTSC, PAL and SECAM colour television systems. 33 E.B.U. Colour television standards: Report of the E.B.U. ad hoc Group on Colour Television. 34 United States of America Influence of clutter on the ratio of picture and sound terminal voltage. 35 United States of America The need for receiver colour controls in any system of colour television. 38 E.B.U. Colour television standards. 39 United Kingdom Controllability of NTSC receivers. 40 United States of America Comments on C.C.I.R. Doc. 33 (2nd Rev.), London 1964: Report of Study Group XI Colour Sub-Group. 41 United Kingdom Colour television. 43 United Kingdom Proposed sub-carrier pilot for NTSC-type colour television. 44 P. R. of Poland Comparative assessment of the compatibility of the NTSC and SECAM III systems. 45 E.B.U./O.I.R.T. Comparative tests of the transmission of colour television pictures over long international circuits. 46 France Some results of comparative measurements on the SECAM, PAL and NTSC colour television systems— Demonstrations offered by the O.R.T.F. to the members 47 France Colour television recording. (X/44) 48 France Exchange of colour programmes between countries with different standards. 49 United Kingdom Choice of sub-carrier line and field frequencies for a dual standard colour television system. 51 Switzerland Tests of colour reception with domestic receivers. 52 Italy Standards for radiated colour-television signals—Investi gation on the manual tuning of domestic monochrome and colour television receivers. 53 Italy Compatibility of NTSC, SECAM III and PAL emissions using domestic receivers. 54 Italy Colour picture of NTSC, SECAM III and PAL emissions using domestic receivers. 55 P. R. of Poland Comparison of NTSC and SECAM III systems. 56 P. R. of Poland Behaviour of the NTSC and SECAM III colour television systems under the simultaneous influence of various distortions and disturbances. 57 Federal Republic of Germ; colour television system in the presence of statistically distributed noise. Rep. 406 — 48 —

Doc. XI 1963-1966 Submitted by Title 58 France Experiments in colour television broadcasting with the SECAM system. 59 France Compatibility of the NTSC, SECAM and PAL colour television systems on commercial receivers. 67 United Kingdom The behaviour of the SECAM system in the presence of distortions encountered on existing long-distance trans mission circuits. 6 8 Japan Transmission of colour television signals over long dis tances. 70 United Kingdom Colour television standards: Comments on Doc. XI/33. 72 United Kingdom Compatibility of NTSC, SECAM III and PAL colour television systems. 75 United Kingdom Statement by the United Kingdom delegation. 77 France Outline of reply to Doc. XI/40, submitted by the United States of America. 78 and Italy Example of a PAL colour television receiver. Corr. 1 79 Federal Republic of Germany Statement as regards the choice of a colour television system. 80 Netherlands Statement by the Netherlands delegation. 81 P. R. of Poland Statement regarding the choice of a colour television system. 82 U.S.S.R. Statement on the choice of a single-colour television system. 84 P. R. of Bulgaria Statement regarding the choice of a colour television system. 85 Italy Statement by the Italian delegation. 87 Japan Statement by the Japanese delegation. 92 Spain Statement on the choice of a colour television system. 93 France Letter to Chairman of Study Group XI. 94 France Note on the comments made on the SECAM system. 96 United States of America Statement regarding the choice of a colour television system. 1 1 2 P. R. of Poland Remarks concerning Doc. XI/96. 116 Working Party XI-A Report by the Chairman of Working Party XI-A.

Later documents of Study Group XI, period 1963-1966

143 Federal Republic of Germany Central correction of the phase error in PAL colour television signals. 154 People’s Republic of Poland Use of monochrome television equipment now in opera tion in Poland for colour television. 155 Netherlands Correction in transmitters for group-delay errors. 167 Switzerland Contribution to the theoretical study of the problem of colour television multipath reception. 178 France Linear pre^correction of systetn L television transmitters. — 49 — Rep. 407-1

REPORT 407-1 *

CHARACTERISTICS OF COLOUR TELEVISION SYSTEMS **

(Question 1/11)

(1966-1970)

This document describes the characteristics of the different colour television systems in use or under consideration at the time of the Xllth Plenary Assembly, New Delhi, 1970.

A. CHARACTERISTICS OF THE NTSC COLOUR TELEVISION SYSTEM DERIVED FROM SYSTEM M ***

1. Video-frequency characteristics (Table I of Report 308-2)

Number of lines per picture (frame): 525 Field frequency (fields/s): 59-94 Interlace: 2/1 Picture (frame) frequency (pictures/s): 29-97 Line frequency (lines/s): 15 734-264 Tolerance (lines/s): ±0-044 Aspect ratio (width/height): 4/3 Scanning sequence (line): Left-to-right (field): Top-to-bottom System capable of operating independently of power supply frequency: Yes Approximate gamma of picture signal: 0-45 (1/2-2) Nominal video bandwidth (MHz): 4-2 Chrominance sub-carrier frequency (MHz): 3-579545 Tolerance (Hz): ±10

A burst of at least eight cycles at the frequency of the chrominance sub-carrier occurs during each horizontal blanking period after the line-synchronizing pulse and at least 0-006 H from the trailing edge of that pulse and lasts until not more than 0-125 H from the leading edge of the same line-synchronizing pulse. The zero axis of the colour-burst is at the blanking level and its peak-to-peak amplitude about the blanking level is from 0-90 to 1-1 of the difference between the levels of the synchronizing pulses and the blanking level.. This colour burst is omitted during the field-blanking period.

* This Report was adopted unanimously. ** Study Group XI was not able to issue a Recommendation for a single colour television system. The report by Sub-Group XI-A-2, which was asked to work out a solution to this problem at the Xlth Plenary Assembly, Oslo, 1966, is annexed. *** These characteristics are those given in Doc. XI/128 (U.S.A.), 1963-1966. Rep. 407-1 — 50 —

1.1 Composition o f the colour-picture signal

1.1.1 Em = E'y + [ E'q sin {cot + 33°) + Ej cos (cot + 33°) ] where E'q = 0-41 CE'b - E'y ) + 0-48 (E'r - E'y). Ej = -0-27 (E'b - E'y) + 0-74 {E'r - E'y). E'y = 0-30 E'r + 0-59 E'g + O il E'b.

For colour-difference frequencies below 500 kHz (see § 1.1.2), the signal

e m = e y + | y ^ 4 (e b ~ e 'y> s in + ( e r - e y ) cos 0)1 j

where

Em is the total video voltage, corresponding to the scanning of a particular picture element, applied to the modulator of the picture transmitter. E'y is the gamma-corrected voltage of the monochrome portion of the colour picture signal, corresponding to the given picture element. E'q and Ej are the amplitudes of two orthogonal components of the chrominance signal corresponding respectively to narrow-band and wideband axes. Ejj, E'g, and E'b are the gamma-corrected voltages corresponding to red, green and blue signals during the scanning of the given picture element. co is the angular frequency and is 2n times the frequency of the chrominance sub-carrier. The portion of each expression between brackets in § 1.1 represents the chromi nance sub-carrier signal which carries the chrominance information.

The phase reference in the EM equation in § 1.1 is the phase of the burst + 180°. The burst corresponds to amplitude-modulation of a continuous sine-wave.

1.1.2 The equivalent bandwidths assigned prior to modulation to the colour difference signals E'q and Ej are as follows:

2 -channel bandwidth: at 400 kHz, less than 2 dB down; at 500 kHz, less than 6 dB down; at 600 kHz, at least 6 dB down.

/-channel bandwidth: at 1-3 MHz, less than 2 dB down; at 3-6 MHz, at least 20 dB down.

1.1.3 The gamma-corrected voltages, ER, E'g, and E'b, are suitable for a colour picture tube having primary colours with the following chromaticities in the C.I.E. system of specification: x y Red {R) 0-67 0-33 Green (G) 0-21 0-71 Blue (B) 014 0 08 — 51 — Rep. 407-1

and having a transfer gradient (gamma exponent) of 2 - 2 associated with each primary colour. The voltages E'r , E’g and E’b may be respectively of the form E 1^7, E Gy and E lJv, although other forms may be used with advances in the state of the technique.

1.1.4 The radiated chrominance sub-carrier vanishes on the reference white of the scene.

Note. — The numerical values of the signal specification assume that this condition will be reproduced as standard illuminant C (x — 0-310, y = 0-316) of the International Lighting Commission (C.I.E.).

1.1.5 E y , E'q , Ej and the components of these signals match each other in time to 0-05 [as.

1.1.6 The angle of the sub-carrier measured with respect to the burst phase, when reproducing saturated primaries and their complements at 75% of full amplitude, are within ± 10° and their amplitudes are within ± 20 % of the values specified above. The ratios of the measured amplitudes of the sub-carrier to the luminance signal for the same saturated primaries and their complements fall between the limits of 0 - 8 and 1 -2 of the values specified for their ratios.

2. Radio-frequency characteristics (Table I of Report 308-2)

Nominal radio-frequency bandwidth (MHz): 6 Sound-carrier relative to vision-carrier (MHz): + 4-5 Nearest edge of channel relative to vision carrier (MHz): - 1-25 Nominal width of main sideband (MHz): 4-2 Nominal width of vestigial sideband (MHz): 0-75 Type of polarity of vision modulation: A5C, negative

Synchronizing level as a percentage of peak carrier: 1 0 0 Blanking level as a percentage of peak carrier: 72-5-77-5 Difference between black level and blanking level as a percentage of peak carrier: 2-875-6-75 Peak-white level as a percentage of peak carrier: 10-15 Type of sound modulation: F3, ± 25 kHz 75 [as pre-emphasis Ratio of effective radiated powers of vision and sound: 10/1-5/1

Details of line-synchronizing signals (Table II of Report 308-2)

%H [AS Line period (//): 1 0 0 63-556 Line-blanking interval (a): 16-5-18 10-5-11 4

Interval between time datum (H0) and back edge of line- blanking signal 0 b): 12-7-16 806-10-3

Front porch (c): % 2 > 1-27 Rep. 407-1 — 52 —

XoH [as

Synchronizing pulse (d) : 6 -6 - 8 4-2-5 1 Build-up time (10-90%) of the edges of the line-blanking signal (e): <0-75 <0-48 Build-up time (10-90%) of line-synchronizing pulses (/): 0-4 % 0-25

4. Details of synchronizing signal (Table III of Report 308-2) Field period ( V) : 16-683

Line period (H) ( j a s ) : 63-556 Field-blanking period (j) ([is): 1168-1335 (0-07-0-08) V Approx. (18-21) H

Build-up times (10-90%) of the edges of field-blanking pulses (k) (fAs): ^ 6-36 Duration of first equalizing pulse sequence (/): 3H Duration of synchronizing pulse sequence (m) : 3H Duration of second sequence of equalizing pulses (n): 3H

%H [as Duration of equalizing pulse (p): 3-6 2-29 Duration of field-synchronizing pulse (q): 41-6-44 26-4-28-0

Interval between field-synchronizing pulses (t"): 6 - 8 -8 3-8—5 Build-up times (10-90%) of edges of synchronizing signals (5): ^ 0-4 <0-25 B. CHARACTERISTICS OF THE PAL COLOUR TELEVISION SYSTEMS DERIVED FROM SYSTEMS M, B, G, H AND I

SPECIFICATION OF THE PAL SYSTEM: OCTOBER, 1967 (for tolerances suggested for signals radiated from transmitters wholly within a national boundary, see section II) ,

Systems 0) Item Characteristics / B, G and H M

1 General specification

Luminance component Amplitude modulation of the icture carrier Chrominance component Simultaneous pair of componeiits transmitted as amplitude-modula ted sidebands of a pair of suppressed sub-carriers in quad rature having a common frequency

2 Colour sub-carrier frequency, fs c fs c = 4433618-75 Hz fs c = 3575611-49 Hz

3 Frequency spectrum of composite colour vision and sound signals

Vision-to-sound spacing 6 MHz - 400 Hz = 5-9996 MHz 5-5 MHz 4-5 MHz Main sideband 5-5 MHz 5-0 MHz 4-2 MHz Vestigial sideband 1-25 MHz 0-75 MHz (3) 0-75 MHz Chrominance sidebands (2) Ev signal \ ( + 1-07 MHz | ( +0-57 MHz 1 [ + 0-6 MHz ] fsc | > nominal fs c < / nominal fsc s > nominal Ev signal J ( - 1-3 MHz j ( - 1-3 MHz j ( - 1-3 MHz )

(l) Monochrome systems, the characteristics of which are given in Table I of Report 308-2. (a) See item 8. (3) System H has a vestigial sideband of 1-25 MHz. Systems Item Characteristics I B, G and H M

4 Synchronizing and blanking Complies with Report 308-2 with the following modifications: waveform Sub-carrier Duration: 10 cycles 9 cycles Colour synchronization burst Start: 5- 6 pis after the leading edge 0 H of the line-sync. 5-8 pis after the leading edge 0 R oi pulses. line-sync. pulses. See u in Fig. 1. See w in Fig. 1. Peak-to-peak value: 3/7 of the difference between white and blankirlg levels (equal to nominal video- sync, pulse magnitude prior to transmission (4)) See Z in Fig. 1. Phase sequence relative to the + Ev axis taken as the pflase reference: On odd lines of the first and second fields and oil even lines of the third and fourth fields, the phase of burst is +135°, see B1 in F ig. 1 . On even lines of the first and second fields and c n odd lines of the third and fourth fields, the phase of the burst is —135°, see B2 iil Fig. 1. Blanking: the colour bursts shall be omitted during 9 lines the colour bursts shall be omitted of each field-blanking interval in the manner during 11 lines of each field-blanking shown in Fig. la . interval in the manner shown in Fig. lb .

(4) The phrase “prior to transmission’ ’ is used to avoid taking into account the differences between the systems (/, B, G and H) in the transmitted ratio of picture signal amplitude to synchronizing signal amplitude. The magnitude of the video-synchronizing pulse prior to transmission is taken to be 3/7 of that of a transition from blanking level to white. Systems Item Characteristics I B, G and H M

5 Pre-correction at the transmitter for none —0-17 [as at fsc relative to low not yet known receiver group-delay characteristics. video frequencies (s)

6 Scanning

Line-scanning frequency, f H / h = 4/sc/(1135 + 4/625) f H = 4/sc / 909

7 Equation of colour picture signal EM = E'y + 4 sin

Er , E g EB = and gamma- The sign before E v cos a set is positive during odd lines of the first and second fields and during even precorrected voltages corre lines of the third and fourth fields as in item 4 (colour synchronization). sponding to the red, green and blue signals. (A display gamma of 2-8 1 (A display gamma of about 2-8 is assumed) is assumed) |

8 Bandwidth of video colour- at 1-3 MHz < 3 dB down difference signals: E v and Ev at 4 MHz > 20 dB down

9 C.I.E. (1931) primary colour red (x = 0-64 y = 0-33) red (x = 0-67 y = 0-33) chromaticities of picture tube for green (x — 0-29 y = 0-60) green (x = 0-21 y = 0-71) blue (x = 0-15 y = 0-06) blue (x = 0-14 y = 0-08) which Er , E g and EB are suitable.

Chromaticity for ER = E G = EB Chromaticity for ER = EG = EB shall match that of illuminant shall match that of illuminant D 6500 C (x = 0-310 y = 0-316) (x = 0-313 y = 0-329) e. 407-1 Rep.

(6) In the Netherlands, the specification of the pre-correction at the transmitter for receiver group-delay characteristics is as follows: a sinewave introduced at those terminals of the transmitter, which are normally fed by the encoded colour video signal, shall produce a radiated signal having an envelope delay, relative to the average envelope delay between 0-05 MHz and 0-20 MHz as indicated in the Table and Fig. 3. From Doc. XI/170 (Spain), 1966-1969, it is learned that this same group delay correction is used for transmitters in Spain. SUGGESTED TOLERANCES FOR SIGNALS RADIATED FROM TRANSMITTERS WHOLLY WITHIN A NATIONAL BOUNDARY

Number Number Suggested tolerances for radiated signal of item of item in main in tole Characteristics spec. rance spec. System I Systems B, G and H System M

2 i Colour sub-carrier frequency: 4433618-75 Hz ± 1 Hzf1) 4433618-75 Hz ± 5 Hz 3575611-49 Hz ± 10 Hz

4 Duration of sub-carrier ii 10 cycles ± 1 cycle (2-25 [is ± 0-23 (is) 9 cycles ± 1 cycle burst: (2-52 [as ± 0-28 [as)

4 iii Start of sub-carrier burst: 5-8 [as ± 0-1 [as 5-6 [as ± 0-1 [ is (4) after epoch O h after epoch O h

4 iv Peak-to-peak value of sub carrier burst: equal to nomi nal video-sync, pulse magni ± 1 0 % of nominal video-sync, pulse magnitude prior to transmission (2) tude prior to transmission (2). See Fig. 1 (3).

4 V Amplitudes of bursts on successive lines shall not differ by more than 5 % of the greater. See Fig. 1.

4 vi Phase angle of successive bursts: ±135° with respect to axis of phase reference, ± 1° + Ejj. See Fig. 1.

7 vii Colour picture signal: •Ejvf = Ey 4" Ey sin(wscf) 0 = 1° (See Fig. 1) ± Ey cos(toscf ± 0 )

0) This tolerance may not be maintained during such operational procedures as “gen-lock”. (2) The phrase “prior to transmission” is used to avoid taking into account the differences between the systems (/, B, G and H) in the transmitted ratio of picture signal amplitude to synchro nizing signal amplitude. The magnitude of the video-synchronizing pulse prior to transmission is taken to be 3/7 of that of the picture signal. (3) For the use of automatic gain control circuits, it is important that the burst amplitude should maintain the correct ratio with the chrominance signal amplitude. (4) Transmitter pre-correction for receiver group delay is not included. — 57 — Rep. 407-1

C. CHARACTERISTICS OF THE SECAM III COLOUR TELEVISION SYSTEM

The main technical parameters of the colour television broadcasting system which is compatible with all 625-line black-and-white television systems except N are given below.

1. Main characteristics of the picture analysis The main characteristics of the analysis are the same as in the C.C.I.R. 625-line black- and-white television systems. (See Report 308-2.)

2. Characteristics of the composite video signal (at the transmitter input) 2.1 The composite video signal contains the luminance signal and the chrominance signal. The spectrum of the chrominance signal lies within the limits of the spectrum of the luminance signal. 2.2 The luminance signal E y corresponds to the expression:

E'y = 0-299 E'r + 0-587 Eq + 0 114 where: F' = plly- f ' — F1^- F' — F1^ ’ G G ’ B B ’ Er, Eg, Er \ are the video signals for the primary colours red, green and blue.

y: is' the exponent of the transfer characteristics of the receiver tube as a function of the signal voltage and is approximately 2 -2 .

2.3 The signals ER, EG and EB correspond to the primary colours of a receiver with the following chromaticity coordinates (C.I.E. x-y system - 1931).

— red * = 0-67 y = 0-33 — green x — 0-21 y = 0-71 — blue x — 0-14 y = 0-08

The reference illuminant corresponding to equality of the primary signals, Er =^E'g = E'b, is the illuminant C

x = 0 310 y = 0-316 The maximum luminance value corresponds to the unit value of the signals ER, EG and Eb.

2.4 The chrominance signal is a sub-carrier frequency-modulated sequentially line-by-line by two colour-difference signals.

2.5 The colour-difference signals correspond to the expressions:

d r - - ^ { e r- e 'y)

K = (K -E y )

Note. — The coefficients mentioned in §§ 2.2,2.3 and 2.5 could be changed if more favourable luminophores were chosen for the receiver tube. Rep. 407-1 — 58 —

2.6 During transmission of C.I.E. type C white-source chrominance signals (E r = Eq = EB), the colour-dilference signals Dr and D'b are nil.

2.7 The colour-difference signals DR and Db are low-frequency pre-corrected before modulation of the sub-carrier by means of a network with a transmission factor expressed by the formula:

ABF( f) = [1 + j(///1)]/tl +j(//3A )l

where / is the frequency (kHz) f x = 85 kHz.

The colour-difference signals also have their spectrum limited by means of a filter the attenuation of which must not be less than 20 dB at frequencies equal to or higher than 3 0 MHz. , The overall nominal transmission factor resulting from pre-correction and limitation of the spectrum is shown in Fig. 4.

2.8 The sub-carrier is frequency-modulated by pre-emphasized signals, the spectrum of which is limited as described in § 2.7, i.e. by D^* and Db*.

The equation of the modulated chrominance signal for constant values of the signals Dr * and D'b* is:

m (t) = M cos 2n. (/Q + D'*. A /0) . t

in which f Q, A / 0 and D'* are, respectively:

— the frequency corresponding to the absenceof chrominance components f OR, thenominal deviation A f QR and the pre-emphasized signal Dr * for the line Dr ;

— the frequency corresponding to the absence of chrominance components f QB, the nominal deviation A f QB and the pre-emphasized signal Db * for the line Db.

The nominal values of the frequencies (kHz) corresponding to the absence of chromi nance components and of the deviations are as follows: f OR = 4406-25 (± 2 kHz) A f QR = 280 f oB = 4250-00 (± 2 kHz) A f QB - 230

The maximum frequency deviation A f Q (kHz) is limited to the following nominal values:

+350 and —500 for the lines Dr +500 and —350 for the lines Db

This limitation occurs at the transitions to the excess values introduced on DR* and Db* by the pre-correction specified in § 2.7. — 59 — Rep. 407-1

2.9 At the beginning of the line, the frequencies corresponding to the absence of chrominance components are controlled so that they are either in the same phase as, or in phase opposition to, a permanent sinusoidal signal of frequency: f RR = 282. f H = (282 x 15 625) Hz for f QR f BB = 272. f H = (272 x 15 625) Hz for f QR

A phase change of 180° is carried out during one line at every third line and addi tionally at every alternate field, producing the cycle 0-0-180° at odd fields and 180°-180°-0 at even fields.

2.10 The chrominance signal is subject to a high-frequency amplitude pre-correction by means of a corrective network with a transmission factor expressed by the formula:

A h f (/) = (i + j- 16F> / C1 + J-1 2 6 F )

where F = f/fQ — fQ / / and f 0 = 4286 00 kHz

The nominal curve of the high-frequency correction is shown in Fig. 5.

2.11 The nominal peak-to-peak amplitude of the colour sub-carrier at the minimum transmission factor of the high-frequency corrective network specified in § 2 . 1 0 is 23% of that of the luminance signal.

2.12 The colour synchronizing signals (line identification) required for synchronous operation of the receiving and transmitting switches are transmitted during 9 lines of the field blanking interval, i.e. on lines 7 to 15 in the first field and 320 to 328 in the second field.

These identification lines are made by the colour sub-carrier /which is frequency- modulated sequentially by the signals:

— Dr varying trapezoidally, linear at the beginning of the line for 15 ± 5 fxs between 0 and +1 -25 followed by a porch at the level +1-25 ±013;

— Db varying trapezoidally, linear at the beginning of the line for 20 ± 10 jxs between 0 and —1-50 followed by a porch at the level -1-50 ±015.

The colour synchronizing signals have the appearance shown in Figs. 6 (a) and 6 (b) before modulation of the sub-carrier and the appearance shown in Fig. 6 (c) after its modulation.

2.13 The chrominance signal is suppressed: — during a time interval of 6-7 to 7-8 [xs beginning with the line blanking signal; — during a time interval beginning with the field blanking signal but excluding the trans mission time of the colour synchronizing signals defined in § 2 .1 2 .

2.14 To eliminate intermodulation distortion, the colour sub-carrier of the system may be further amplitude-modulated by a signal depending on the luminance signal components which lie within the frequency band of the chrominance signal. Rep. 407-1 — 60 —

2.15 The luminance signal is transmitted in the nominal frequency band of the black-and-white system from which it is derived.

3. General transmission characteristics of the video and sound signals (transmission by radio channel) The general characteristics of the transmitted signal correspond to the C.C.I.R. standards for the 625-line black-and-white television system from which the signal is derived. (See Report 308-2.)

D. SPECIFICATION OF THE SECAM IV COLOUR TELEVISION SYSTEM *

In view of Doc. XI/162 (Belgium), 1963-1966, with reference to the NIIR—SECAM IV colour television system, the delegations of France and the U.S.S.R. consider it necessary to publish on behalf of their respective Administrations the documents annexed hereto which describe the said SECAM IV system that has been jointly developed and tested by French and Soviet experts. Both delegations consider that the annexed documents constitute the only source of information capable of giving a precise idea of this version of the SECAM system. Both delegations wish to point out that the SECAM III version is better prepared for industrial production than the SECAM IV variant, that successful international demon strations have been made of it in transmissions by radio-relay and via the Soviet satellite Molniya I, whereas the SECAM IV version—although also at a high technical level—has no decisive advantage over SECAM III and is still being developed. France and the U.S.S.R. therefore prefer the SECAM III version.

CHIEF TECHNICAL CHARACTERISTICS 1. Signals transmitted SECAM IV is compatible with standard black-and-white 625-line television systems, except system N. The luminance signal is obtained from gamma-corrected primary signals Er , Eg, E'b, and corresponds to the equation:

E'y = 0-30 E'r + 0-59 E'g + 011 E'b

The colour information is transmitted by two colour-difference signals:

253 Before modulation, the frequency band of the colour-difference signals occupies more than 1-5 MHz.

2. Transmission procedure The colour-difference signals are transmitted by modulation of a sub-carrier. They are differentiated from one line to the next as follows: Signal transmitted during one of the lines

Es1 = V Dr2 + Db2 + Ep cos [co0t + 9 (01

* This specification is reproduced from Doc. XI/169 (France and U.S.S.R.), 1963-1966. Signal transmitted during the following line

Es2 = V D'r 2 + D'b2 + Ep cos (co0t +

VD'r + Db ' and where

9 ( 0 = arc tan (D'b/D'r )

Frequency of the colour sub-carrier

The frequency of the colour sub-carrier is equal to : / 0 = 4-43361875 MHz. It is related to the line sweep frequency fu ne = 15 625 Hz by the following equation:

fo — (284— l/4)/jine + 25 Hz.

Colour synchronization signal The receiver switch is synchronized by synchronization signals transmitted with the composite video signal. They represent six wave trains of the colour sub-carrier, each train lasting about 40 p,s. They are transmitted during the field returns in the 6 th -llth lines of the first field and in the 319th-324th lines of the second field. During the even lines, the sub carrier phase in the train is 9 = 90°, and during all the odd lines 9 = 180°. The amplitude of each wave train is equal to 30 % of the composite signal E y measured between the white and black levels.

Reception procedure

The colour-difference signals Dr and Dg are obtained by multiplication of the trans mitted signals E ^n + and E2n, each signal being delayed in turn by the duration of one line. The level of the signal E2n must be 10 to 20 times higher than that of the signal E ^n + ir

To obtain the correct polarity for the signals Eb y and ERY at each line, a switch working to the line periodicity is used.

ANNEX

REPORT BY SUB-GROUP XI-A-2 TO THE X lth PLENARY ASSEMBLY, OSLO, 1966

Sub-Group XI-A-2 met on 7 and 8 July, under the chairmanship of Mr. E. Esping and with the participation of the following delegations: United States of America, France, Italy, Netherlands, Federal Republic of Germany, United Kingdom, Switzerland, Czechoslovak Socialist Republic, U.S.S.R. and Federal Socialist Republic of Yugoslavia.

The Sub-Group considered first whether a compromise could be reached on recommending a single world-wide colour television system. The conclusion was quickly reached that this was impossible in view of the fact that the system already in public service in countries using the 525-line standard was not generally acceptable elsewhere. The U.S.A. suggested that for international programme exchange, colour television signals could be relayed on 625 lines either in NTSC or PAL form, according to the wishes of the receiving country. Alternatively, Rep. 407-1 — 62 —

the delegation of the United States of America suggested that world-wide adoption of the ART (Additional Reference carrier Transmission) system for broadcasting would in its view offer the advantage of permitting the use of existing NTSC receivers on the ART trans mission. In the view of the delegation of the U.S.A. this system would also appear to offer the same advantages as SECAM or PAL. These two proposals received no support.

2. Attention was therefore turned to the possibility of agreeing on a single system of 625-line colour television for use in countries which have adopted this line standard, and to begin with in the area in which several countries have announced their intention of starting regular colour television services towards the end of 1967.

3. During the discussions, Doc. XI/179 (Denmark) was referred to by the U.K. delegate. A compromise system is proposed in this document. The delegate specially referred to § 8 in the document: “The Danish delegation suggests that a questionnaire be addressed to those members of the Study Group operating or contemplating the introduction of 625-line colour television, asking whether they would be prepared to support this system if all other dele gations were prepared to do the same.” To find out if unanimous agreement on this suggestion would be possible, the Chairman consulted the members of the Sub-Group. The result of this consultation was that no agree ment could be reached.

4. Noting that the SECAM IV system has been the only system proposed, even by certain supporters of PAL, as being capable of constituting a possible compromise leading to the adoption of a single European colour television standard, the French delegation—speaking on behalf of the other delegations present who have already accepted SECAM III—declared itself ready to abandon SECAM III and to adopt SECAM IV.

Such a decision would necessarily imply a delay (which could be reckoned at about six months) in the introduction of a regular colour television system in countries of the European area which have decided to introduce such a system in autumn 1967. All the countries interested in the introduction of a colour television system in Europe should put this period to good use by pooling the necessary resources to perfect the final version of SECAM IV. Since the possible adoption of SECAM IV by France and its partners represents the extreme limit of what these countries are prepared to sacrifice in this respect, it goes without saying that all the countries interested in starting a regular colour television system in autumn 1967 will have to participate, within the full measure of their resources, in this research and development work during the period of six months or more in which the final version of SECAM IV is perfected. It is also understood that they will accordingly refrain from any measures which, particularly as regards the manufacture of receivers, might run counter —directly or indirectly—to the common work which they would have defined. N

Moreover, in view of the imperative need to avoid any useless delay, it should be clearly understood that agreement to the above-mentioned principles should be given as soon as possible, and in any case early enough before the end of the present Plenary Assembly of the C.C.I.R. Having heard the replies of the delegations of the United Kingdom and of the Federal Republic of Germany (given below), the French delegation, noting that these two delegations did not accept its proposal which was supported by the delegations of the Czechoslovak Socialist Republic, the U.S.S.R. and the Federal Socialist Republic of Yugoslavia, declared that it was obliged to withdraw it. — 63 — Rep. 407-1

Statement o f the delegations o f the Federal Republic o f Germany and o f the United Kingdom

The delegations of the Federal Republic of Germany and of the United Kingdom said that, quite apart from the fact that the system SECAM IV, unlike PAL, is not yet ready for commercial exploitation, the proposal advanced by the French delegation raised other difficulties. The questions (a) of setting back the dates by which colour television services would be introduced, involving modification of the decisions of governments and (b) of agreeing to abstain from all industrial development incompatible with the joint development of SECAM IV (see the text of the French proposal), were quite outside the competence of the C.C.I.R. It would therefore be clearly impossible to obtain decisions on these matters by the time limit set by the French proposal. Nevertheless, it was desired to have a more precise definition of the proposals for the consideration of Administrations and governments. In any case, the delegations of the Federal Republic of Germany and the United Kingdom would be happy to continue the joint study of SECAM IV.

* Rep. 407-1 — 64 —

Systems Item I, B, G and H M 3 , 0-3 Z 7 * ~ T

b 1 0 -5 [xs 8-9 - 10-2 [xs 1 so

d 4-7 [xs -p

u 5-6 [xs ± 0-1 [xs 5-8 [xs ± 0-1 [xs

V 2-25 [xs ± 0-23 [xs 2-52 [xs ± 0-28 [xs

F ig u r e 1 Colour synchronization and chrominance axes — 65 — Rep. 407-1

Notes 1. S, the nominal video-sync, pulse magnitude prior to transmission, is taken as equal to 3/7 of the difference between white and blanking levels. 2. On odd lines of the first and second fields and on even lines of the third and fourth fields the burst is Bj. On even lines of the first and second fields and on odd lines of the third and fourth fields the burst is B2. 3. 0-95 < B1/B2 < 1-05 as transmitted. 4. The burst shall be omitted during 9 lines in the field blanking interval in the manner shown in Fig. 2.

F i g u r e 1 (contd.) Colour synchronization and chrominance axes e. 407-1Rep.

A B / ~ V IV

308 I 309 I 310 irmTuuuiA^nmi_nrnru 311 I 312 I 3 3 I 314 I 315 I 316 I 317 I 318 I 319 I 320

A | B LAiuionimnruTUI iI P 621 u I 622 ^ I n 6^3 n I 624n n I 625 r 1 I 2 I 3 I 4 I 5 I

' r \ / n i ^ J i i m n n r it i n r 308 I 309 I I 311 I 312 ! 3 LiuuuLnnrm3 I 314 I 315 I 316 I 317 I 318 | 3 9 320 3-jo A I III I I % irim rm n n n LMJuunnnrnrnlli} I 621 I 622 | 6^3 I 624 I 625 1 I 2 I 3 I 4 I 5

C < III

F i g u r e 2 a PAL: Field blanking interval—Systems I, B, G and H Ov: field synchronizing datum. I, II, III, IV: first, second, third and fourth fields. A: phase of burst; nominal value +135°. B: phase of burst; nominal value —135°. C: burst blanking intervals. O \d I • F A B n r \ 1 1 L y U IITTTYYIjuuuuuinnnriwHrirT 519 I 520 I 521 I 522 523 I 524 I 525 112131415161718191

F F F A B II jTTTTruuLfuuuinnnnnrirnr IT I 257 I 258 I 259 260 I 261 I 262 I 263 I 264 I 265 I 266 I 267 I 268 I 269 I 270 271 i I 272 I I F F* F I I A B I u. I J t TTlTTlAAJUUUITTTTTirT r r I 519 I 520 I 521 | 5?2 523 I 524 I 525 j 1 I 2 I 3 I 4 I 5 I 6 I 7 I 9 I 10

F* F

IV ~ w u m u- I 257 I 258 2j>9 2(jiQ I 261 I 262 I 263 I 264 I 265 I 266 I 267 I 268 I 269 1 I 272

C < III

F i g u r e 2b PAL: field blanking interval—System M

Ov: field synchronizing datum. 407-1 Rep. I, II, III, IV: first, second, third and fourth fields. phase of burst; nominal value +135°. phase of burst; nominal value —135°. burst blanking intervals. Rep. 407-1 — 68 —

Frequency (MHz)

Table 2 25 MHz 60 pis ± 50 pis 3 0 0 MHz 60 pis ± 50 pis 3 75 MHz 0 plS ± 50 pis 4 43 MHz - 170 pis ± 35 pis 5 0 0 MHz - 300 pis ± 75 pis

F ig u r e 3 — 69 — Rep. 407-1

Frequency (kHz)

F ig u r e 4 Curve showing the low-frequency correction and limitation of the spectrum of the signals DR and DB e. 407-1 Rep.

Frequency (kHz)

F ig u r e 5 Nominal curve of frequency correction f(kHz) |

(a)

Relative values of the modulating signal e. 407-1 Rep.

F i g u r e 6 Colour synchronizing signals Rep. 476 — 72 —

REPORT 476 *

COLORIMETRIC STANDARDS IN COLOUR TELEVISION

(Study Programme 1 A/ll)

(1970) 1. In 1953, when the NTSC colour television system was adopted for transmission in the U.S.A. the colorimetry of the system was based on three specific primary colours and a reference white. The coordinates of the primaries were: red x = 0-67 y = 0-33 green x = 0-21 y = 0-71 blue x = 014 y = 008

The reference white chosen was standard white C : x = 0-310 y = 0-316

2. In the PAL and SECAM systems the colorimetric standards of the NTSC system were adopted without change.

3. At the Final Meeting of Study Group XI, Geneva, 1969, these colorimetric standards were discussed again. The fact that the colour phosphors used in present-day colour tubes no longer have the coordinates of the standard primaries has led, in the United Kingdom, to a new colorimetric standard for their colour television service (using PAL System I) [1]. The Nether lands introduced a document [2 ] proposing a compromise standard ** between the traditional 1953 standard and the new United Kingdom standard.

4. In the discussions, a number of delegations expressed the opinion that at this moment no change in the colorimetric standards adopted by their Administrations would be acceptable and that the question whether a change will be desirable in the future needs a careful appraisal of all the consequences. It is therefore suggested that further consideration be given to § 1 of Study Programme 1 A/11.

B ibliography 1. C.C.I.R. Doc. XI/136 (United Kingdom), 1966-1969, also in Report 407-1 (Part B, § 9). 2. C.C.I.R. Doc. XI/194 (Netherlands), 1966-1969.

* This Report was adopted unanimously. * * This compromise proposal is: red x = 0-66 y = 0-33 green x = 0-25 y = 065 blue x = 0-145 y 0-07 reference white, D x = 0-313 y = 0-329 — 73 — Rec. 472

SECTION 11B: INTERNATIONAL EXCHANGE OF TELEVISION PROGRAMMES

RECOMMENDATIONS AND REPORTS Recommendations

RECOMMENDATION 472

VIDEO-FREQUENCY CHARACTERISTICS OF A TELEVISION SYSTEM TO BE USED FOR THE INTERNATIONAL EXCHANGE OF PROGRAMMES BETWEEN COUNTRIES THAT HAVE ADOPTED A 625-LINE MONOCHROME SYSTEM The C.C.I.R. (1970)

UNANIMOUSLY RECOMMENDS

1 . the video characteristics, given below, for the international exchange of programmes between countries that have adopted a 625-line monochrome television system. In particular, countries that use Systems B, C, D, G, H, I, K, Kx and L will, facilitate programme interchange by adopting these characteristics. Note 1. — The details concerning the line- and field-blanking intervals are listed in the same order and are designated by the same symbols as in Report 308-2.

Note 2. This Recommendation is not intended to apply to Standard N.

2. General characteristics

2.1 Number of lines per picture: 625 2.2 Line frequency and tolerance when operated non- synchronously fn (Hz): 15 625 ± 0 05% (1) 2.3 Field frequency f v (Hz): (2/625) ./i/ 2.4 Picture-frame frequency f p (Hz): fn /6 25 2.5 Gamma of picture signal: approx. 0-4 2.6 Nominal video bandwidth (MHz): 5 or 5-5 or 6 (2) 2.7 Nominal difference between black level and blanking level (as a percentage of the luminance amplitude): ° - o

3. Details of line-blanking interval (3) ({is)

(H ) Nominal duration of a line: 64 (a) Line-blanking interval: 12 ± 0-3 (b) Interval between datum (Oh) and back edge of line- blanking signal (average calculated value for inform ation:) 10-5 (c) Front porch: 1-5 ± 0-3 (d) Synchronizing pulse: 4-7 ± 0-2 (e) Build-up time (10-90 %) of line-blanking edges: 0-3 ± 01 (f) Build-up time (10-90%) of line-synchronizing pulses: ' 0-2 ± Rec. 472 — 74 —

4. Details of the field-blanking interval ((XS) (j) Field-blanking period: 25/7 + a (4) (k) Build-up time (10-90%) of field-blanking edges (pts) as in (e) 0-3 ± 01 (1) Duration of first equalizing pulse sequence: 2-5H or 3/7(5) (m) Duration of field-synchronizing pulse sequence: 2-5/7 or 3/7 (5) (n) Duration of second equalizing pulse sequence: 2-5/7 or 3Z7(5) (p) Duration of equalizing pulse, ([xs) (one half the value given in (d): 2-35 ± 0-1 (q) Duration of field-synchronizing pulse (average cal culated value for information) ((xs): 27-3 (r) Interval between field-synchronizing pulses (jxs) as in (d): 4-7 ± 0-2 (s) Build-up time (10-90 %) of field-synchronizing pulses ((xs) as in (f) : 0 - 2 ± 0 -1

0 Tighter tolerances will be required for precision offset and colour television. Whenever it might be expected that SECAM signals might be transcoded to PAL signals the line frequency of the arriving SECAM signals should be maintained within the tolerances appropriate to the PAL system. Until a value, based on more extensive investigations, becomes available the tolerance recommended in such cases should be 1 x 1 0 -6.

(2) The attention of Study Groups 9,10 and the CMTT is drawn to the desirability of sub sequently standardizing tolerances for corresponding transmission and recording charac teristics applicable to all 625-line systems. For international routine measurements it is suggested that the test signals be based on a single reference frequency which could be 5 MHz. This value does not exclude the use of test signals with spectra extending beyond 5 MHz, particularly by countries using systems with nominal video bandwidth of 6 MHz. For example, this suggestion is not contrary to the use of a frequency close to 6 MHz in a multiburst test signal.

(3) The nominal value of the picture-synchronizing signal ratio is 7/3. For details of permitted tolerances in long-distance transmissions, see Recommendations 421-2, § 2.3 and 451-1, § 3.3.

(4) In the blanking interval, lines 16, 17, 18, 19, 20, 21, and 329, 330, 331, 332, 333 and 334 are reserved for the reception of any special signals.

(5) These values may be subject to revision in the case where a single equalizing pulse system might be adopted (see Doc. XI/115 (United Kingdom), 1963-1966). — 75 — Rep. 311-2

11B: Reports

REPORT 311-2* THE PRESENT POSITION OF STANDARDS CONVERSION (Question 2-1/11, Study Programme 10A/11)

' (1963 - 1966 - 1970) 1. Review of image-transfer standards conversion between television signals having equal or nearly equal field frequencies Ever since the inception of international television relays, recourse has been made to standards conversion when exchanging live monochrome television programmes. The earliest converters consisted of little more than a camera, working in accordance with the desired standards directed at a picture-monitor displaying a picture on the available standards, but over the years such “image-transfer” converters have been the subject of considerable development, although their inherent shortcomings still exist. A review of existing practice may be found in [1 , 16]. There are two essential features of all standards converters. In the first place, components at the line frequency of the incoming signal must be eliminated from the outgoing signal; otherwise beat patterns may result on the converted picture. At the same time, essential picture detail must be retained. The problem is like passing the signal through a filter having a suitable “vertical” frequency response. In practical converters the response of this filter must be a compromise between visibility of spurious patterns and loss of detail in a vertical sense. The converter must store the incoming information until the reading device is ready to use the information. When the conversion involves a difference in the number of lines only, the required storage time is of the same order as the scanning line duration. In interlaced systems, wherein the conversion is field by field, it must be understood that necessarily the vertical definition of the converted picture is reduced to nearly half. This is because all systems of standards conversion, where the persistence of the displayed image is short compared with the field time, must rely on interpolation between successive lines. In the light of these fundamental concepts, it is useful to examine the behaviour of existing converters. Image-transfer converters, employing a display tube and a camera, rely on line broad ening or spot wobble to reduce the component of the incoming line repetition frequency in the information which is read by the camera. The storage is provided partly by the persistence of display tube phosphor and partly by the camera. The storage time is necessarily less than a field period to avoid movement blur, and such converters are, therefore, subject to the fundamental loss of vertical definition which has been described. In addition, they are sub ject to flare and the signal-to-noise ratio is marginal. The use of a photoconductive camera tube improves the signal-to-noise ratio but may introduce some movement blur. Both the display and the camera are non-linear devices and the converter must operate under circum stances suitable for both. In addition, some adjustments are necessary and, under the stress of operating conditions, the best compromise is not always achieved and the picture quality may fall below the best attainable.

2. Review of image-transfer standards conversion between television signals having field frequencies that differ markedly Conversion between monochrome television standards, having field frequencies which differ markedly from one another, requires the introduction of methods and devices, not previously considered to be necessary, for programme exchanges of the type mentioned in § 1 .

* This Report was adopted unanimously. Rep. 311-2 — 76 —

In converters for such exchanges, there occurs an interference between the field frequen cies which, depending upon the difference between them, can have the appearance of an annoying flicker. Although this flicker can be abated by using picture-tube screens having phosphors with long persistence, the portrayal of movement in the scene being televised becomes subject’to error in the form of blurring or smearing. Various means of overcoming the flicker, without suffering excessive loss of clarity of moving pictures, have been adopted.

3. Description of image-transfer standards conversion between television signals when both the field frequencies and the numbers of lines differ in the two standards

In one method [2], the field-synchronizing waveforms of the two standards are combined to produce a suitably shaped correction signal, having a fundamental frequency equal to that of the flicker. The correction signal is used to control the gain of an amplifier through which must pass the converted signal. The point of insertion of the correction signal has recently been changed, so that pre-correction rather than post-correction is used. The variable gain amplifier is now situated in the path of the incoming, unconverted signal, before its arrival at the display cathode-ray tube. This is not an automatic system, the shape of the correcting waveform being adjusted manually for optimum results. In another method [3], the correcting waveform is obtained from a peak detector, which triggers a correcting waveform generator by a signal resulting from the detection of the peak white level of the converted signal. In yet another method [4, 5], a pulse is inserted into the line-blanking interval of the television signal to be converted. The pulse appears as a vertical bright bar on the picture tube and is converted to the scanning standards of the receiving authority by means of the pick-up tube. After conversion, the pulse signal which suffers from conversion flicker is gated and detected, and used to control the gain of an amplifier through which the converted signal must pass.

In a further method [6 ], use is made of a combination of the systems referred to under [2] and [4] and an additional feature which relies upon gated contrast correction which is applied, in a conversion from 50-field television to 60-field television, to every sixth field of the converted signal. The field under consideration derives its picture signal from an image which has been stored for a notably longer period than preceding and subsequent images and the application of contrast correction effects a further improvement in the reduction of flicker. Various picture tubes and pick-up tubes have been used in the above standards converters. In particular, image orthicons, orthicons and pick-up tubes with photoconductive target, have all given performances of a reasonably satisfactory nature.

4. Review of line-store standards conversion between signals of identical field frequency

Considerable attention continues to be paid to various aspects of the problems of con version of television signals from one standard to another. In general, the work can be divided into two main categories corresponding respectively to Question 2-1/11, §§ 1 and 2, and the two points referred to in Study Programme 10A/11. In connection with the first item of Study Programme 10A/11, mention should be made of work which has been carried out to perfect methods of conversion between television signals having identical and synchronized field frequencies, that may be locked to an elec tricity supply frequency (if required), but different line frequencies. This work was directed towards the development of standards converters involving no moving parts and no inter mediate optical or electron-charge image. Two types of such devices, now known as “line- store converters” [7], have been developed. Both types of instrument are based upon the concept of storing each picture element occurring along a scanning line in one of, say, 600 stores, which may consist, in the first type [8 , 1 1 ] of low-pass filters having a passband 1

— 77 — * Rep. 311-2

such that the response of the filter to the signal representing a given picture element in one line of a field, is dying away as the response to the signal representing the homologous picture element in the succeeding adjacent line of the field is reaching its maximum value. In this way, the component at incoming line-scanning frequency is reduced or “ smoothed” in the signal output from each filter. Appropriate interpolation between the lines in the incoming signal may be achieved by suitable selection of filter characteristics. Fast-acting electronic switches select, at the correct instants, the instantaneous values of the incoming signal and apply them to the appropriate low-pass filters. A bank of similar switches samples the outputs from the filters in synchronism with the outgoing line-scanning frequency.

In the second type [9] of line-store converter, simple capacitors replace the low-pass filters and the appropriate interpolation between homologous picture elements on adjacent lines is obtained by generating an interpolation function S (/), which is then arranged to modu late the incoming signal on the one hand, whilst on the other hand the function l-S (/) is arrang ed to modulate the incoming signal after it has been delayed by exactly one incoming line-scan period. The two modulated signals are then added and switched, as in the first type of converter, to a bank of 600 capacitors. Both types of converter could benefit from the use of a store or delay device, having a delay-time equal to the period of one field of the incoming signal. Such a delay device would permit conversion from picture to picture instead of from field to field, and thus the maximum possible vertical resolution permitted by the lower-definition signal involved in the conversion would be approached. It is self-evident that image transfer converters are also capable of benefiting from the application of such a field store or delay device.

In the line-store converter of the type that uses low-pass filters as the storage elements a compound switching system is used. This arrangement greatly reduces the number of high speed switches required. The common input or output circuit is connected to 36 high-speed switches, each of which is, in turn, connected to 16 low-speed switches (i.e. each high-speed switch serves a group of 16 stores within the full array of 576 stores). The fast switches operate at picture-element rate, but the construction is such that the slow switches need operate only at one thirty-sixth of this rate; thus the majority of the switches can be of simple design with a corresponding reduction in cost.

Both converters can be made to reverse the direction of conversion, for example, from 625 lines to 405 lines and vice versa. The converter of the type that uses simple capacitors as storage elements coupled with an interpolator that is external to the storage elements (capacitors) can be made to reverse the direction of conversion by the operation of a switch. It is also possible to construct the low-pass filter type of converter so that it, too, may reverse the direction of conversion by means of a switch.

Both designs of line-store converter achieve a much better picture quality than conven tional converters [12]. The signal-to-noise ratio, grey scale, horizontal resolution and geo metrical linearity are substantially those of the incoming picture. Blurring of movement, inherent in conventional converters, is entirely absent, the static “background” pattern is almost imperceptible and there is no vignetting or loss of resolution in the corners of the picture. The fact that no valves or cathode-ray devices are used means that the converters are available immediately after switching on and their low-power dissipation results in a high order of stability and reliability. Furthermore, the services of an operator are not required.

5. Further work on the conversion between both monochrome and colour signals with markedly different field frequencies

In connection with the second item of Study Programme 10A/11, important work is in progress, aimed at achieving conversion between television signals having markedly different field frequencies. Rep. 311-2 — 78 —

Basically, the problems to be solved are as follows: — the complete incoming picture signal must be stored for at least one field period; — the magnitudes of the signals on successive or, better, on geometrically adjacent lines must be interpolated to derive the most suitable signal magnitude for the appropriate line in the output standard. This output line will usually lie between two lines of the incoming (original) standard; — the magnitudes of successive field signals must also be interpolated so as to maintain continuity in the portrayal of motion when a field is repeated or suppressed.

Methods involving the use of magnetic tape video recorders have been used and when both the number of lines and the number of fields differ between the two signals in question two conversions take place. The greater difficulty, which resides in the conversion of the field frequencies, is overcome by recording entire fields diagonally across the magnetic tape and ensuring that the length of the reproducing head magnetic gap is wider than that of the recording head. For conversion from 50-field to 60-field signals, for example, every third field of each group of five fields of the 50-field signal is repeated once (duplicated) and recorded on the tape adjacent to its previous position. The reproducing head, with its longer gap, is then able to read off the tape six fields (for the outgoing 60-field signal), in a time duration equal to that required by five fields of the incoming signal. To duplicate certain fields of the incoming signal as magnetic stripes on the tape, the recording disc carries two heads so that, for example, when field number three of the incoming signal is present, it can be recorded simultaneously by the two heads as adjacent magnetic stripes on the tape. The device consists of a drum around which is wound, as one turn of a helix, the video magnetic tape. Inside the drum is the disc containing, on its periphery, the two recording heads. The latter protrude through a radial slot in the drum and can, therefore, make contact with the inner side of the single-turn helix of tape.

Such a device has been constructed and performs satisfactorily [10]. Following these experiments, further studies have been carried out in Japan [13] and in the United Kingdom [14] with a view to achieving better performance in the conversion between television standards having markedly different field frequencies than is obtained with earlier forms of standards converters. These studies and experiments are in accordance with Question 2-1/11, § (c), and Study Programme 10A/11, § 2. In principle, a converter of the type envisaged represents an extension of the ideas incorporated in the line-store converter mentioned in an earlier part of § 4. The field-store converter thus contains no intermediate optical image and may or may not contain moving parts depending upon the availability of ultrasonic delay-lines suitable to replace delays of the type that use a rotating magnetic-recording memory disc. Delay time up to the duration of a field of the television standard to be converted are required. In particular, conversions between 60-field and 50-field standards are envisaged.

The processes involved are: — line (store) conversion, in order that the number of lines required for the “output” standard can be obtained from the different number of lines in the standard to be converted or “input” standard. Certain lines are omitted or duplicated; — field conversion, in order that the number of fields required for the output standard can be obtained from the different number of fields in the input standard. Certain fields are omitted or duplicated; — an adjustment effected to account for the different durations of the scanning lines in the input and output standards; — interpolation between lines in order to make an estimate of what picture information would have existed in between the scanning lines of the input standard and to make use of this during certain scanning lines of the output standard, when, as will occur in a cyclic — 79 — Rep. 311-2

manner, the latter (scanning lines of the output standard) would not have been in geomet rical coincidence with the former (scanning lines of the input standard); — interpolation between fields, to make an estimate of the picture information which should exist in each successive output field. (The smooth portrayal of motion has been interrupted as a consequence of omitting or duplicating a field); — compensation for timing errors that occur in the waveform of the output standard.

The order in which the above processes are carried out depends upon the precise design of the field-store converter as well as upon the direction in which the conversion is to take place: 50 fields/s to 60 fields/s or vice versa.

In some proposals [14], the line and field conversions may be combined in one unit comprising many delay-1 ines through which the signal may be switched in accordance with a pre-arranged programme. Using such methods it is possible to convert between standards whose field frequencies are neither in an exact 5/6 (or 6/5) ratio nor in any fixed ratio; thus conversion is possible between standards whose field frequencies are not precisely related. In other proposals [13], conversion in the latter condition is made possible by the use of an additional timing-error compensator. Yet another proposal for a field store converter is based upon a simpler concept which necessitates that the precise ratio of 6/5 (or 5/6) must be maintained between the two field-scan frequencies [19]; also no attempt is made to alter the period of each active field. This leads to a change in the size of the image with respect to the scanned raster. In Japan, a converter [13, 15] which does not change the size of the image has been constructed and actual broadcasts have confirmed the satisfactory conversion of 625-line signals into 525-line signals using this converter. Recently the effective two-way converter which can convert from a 625-line PAL or SECAM signal to a 525-line NTSC signal and vice versa was completed [21]. The direction of conversion can easily be reversed by changing the arrangement of the delay lines and other units. Work to modify the equipment for non-fixed-ratio conversion is continuing.

As a result of work in the United Kingdom, two types of colour converter have been developed [17, 19, 20]. One is based upon the simpler concepts already mentioned while the other uses more advanced techniques which enable it to work with a field-frequency ratio that need not be exactly 5/6 (or 6/5), producing at its output a standard picture signal locked to local station sync, pulses and a standard colour sub-carrier frequency. Conversions by means of the simple and by means of the advanced methods have been achieved in both directions, that is, 525-lines to 625-lines and vice versa. These converters are now fully opera tional and have been successfully used in many international exchanges of programmes. As was predicted from feasibility studies and experiments, improved performance over optical converters has been obtained with respect to resolution, movement blur, flicker, geometric distortion and linearity of response. No adjustment by operators is required and the converters have shown a good degree of reliability.

Work [18, 22] in the Federal Republic of Germany has been directed at improving the technique of optical conversion [16], in view of the fact that at the present state of the art it is the simplest and cheapest method for solving the three basic requirements mentioned earlier. The colour converter designed on this principle uses two separate conversion devices, one for the luminance signal and the other for the chrominance signal. In principle, the incoming signal is divided into its luminance and chrominance components. (So-called “comb-filters” or combinations of high-pass and low-pass filters may be used for this purpose.) In the luminance part of the standards converter the luminance component is converted Rep. 311-2 — 80 —

immediately into the new standard, if necessary after improvement of the signal by means of the crispening technique. In the chrominance part of the standards converter the chromi nance carrier component is transformed into an auxiliary carrier-frequency which: — results in a pattern of vertical stationary stripes in the displayed picture; — is so low that, as far as contrast and horizontal positioning are concerned, the striated structure can easily be resolved by the camera of the chrominance part of the converter. Here, the contrast between the stripes is determined by the colour saturation, and the geometrical position of the stripes is determined by the hue.

For this purpose, use can be made either of a carrier frequency locked to the horizontal frequency (carrier frequency = integral multiple of the horizontal frequency) or of a start- stop oscillation of any frequency having a defined phase relationship at the beginning of each line. To define the horizontal shift of the position of the vertical stripes, a pilot signal has to be superimposed which furnishes a reference phase. After conversion of the chrominance component, the pilot signal is separated from the chrominance signal and transformed into a reference carrier to be used in a subsequent synchronous demodulation of the chrominance signal. The colour difference signals derived in this way are then remodulated with the new colour carrier by conventional technique.

The sum of the standards-converted luminance and chrominance signals yields the colour picture signal at the new standard and coding. It meets all parameters laid down in the specifications.

6. Conclusions

In standards conversion between monochrome television signals having different line frequencies but the same or nearly the same field frequencies, a satisfactory result may be obtained by the well-known image-transfer methods. If the field frequencies are identical, however, new methods, known as line-store conversion, have been perfected. In these methods, no intermediate optical or electron-charge image is used and a more consistent and better quality image is achieved. Furthermore, variations in image quality, due to the human element involved in the operation of standards conversion equipment, are notably reduced by the introduction of these new techniques.

On the other hand, in converting between television signals, from one standard to another, when the field frequencies of the two standards are different, it is possible, by adopting one of the methods described in § 3, to reduce the flicker of the pictures reproduced to a hardly perceptible level, provided the adjustment of the converter is effected correctly. It has been proved that by the use of more advanced techniques the main shortcomings of former electro-optical converters such as low resolution, flickering and smearing in moving pictures can be overcome and this has led to the development in the Federal Republic of Germany of a colour standards converter with electro-optical image transfer. The prototype converter is operating with satisfactory results at the satellite earth station at Raisting.

New methods of conversion which do not require the use of the image-transfer method have been developed, and are now fully operational in the United Kingdom and in Japan. These are field store converters for both monochrome and colour television and use ultra sonic delay lines as the storage medium. — 81 — Rep. 311-2

B ibliography

1. L o r d , A. V. and R o u t , E. R. A review of television standards conversion. Television Engineering I.E.E. Conference Report, Series 5, 167 (1962). 2. H e ls d o n , P. B. A universal television standard converter. Marconi Review, Vol. 25, 147, 4th quarter, 217-234 (1962). 3. B e n so n , K. B. C.B.S. television standards conversion techniques. JSMPTE, 70, 628-632 (August, 1961). 4. (a) C.C.I.R. Doc. XI/2 (Federal Republic of Germany), Bad Kreuznach, 1962. (b) S e n n h e n n , E. Normwandlung von Fernsehsignalen verschiedener Teilbildfrequenzen (A standards converter for television signals with different frequencies). Radio Mentor, 3, 184-188 (March, 1961). 5. (a) L o r d , A. V. A standards converter for television exchanges between Europe and North America. E.B.U. Review, Part A—Technical, 63 (October, 1960). (b) Rout, E. R. and Vigurs, R. F. A wide-range standards converter. J. Tel. Soc., 9 ,12, 493-503 (October-Dezember, 1961). 6 . C.C.I.R. Doc. XI/31 (Japan), Bad Kreuznach, 1962. 7. C.C.I.R. Doc. 266 (E.B.U.), Geneva, 1963. 8 . R a in g e r , P. A new system of standards conversion. International Television Conference, London (June, 1962). 9. L o r d , A. V. and R o u t , E. R. An outline of synchronous standards conversion using a delay-line interpolator. International Television Conference, London (June, 1962). 10. (a) N o m u r a , T. Television standards conversion systems. First International Television Sympo sium, Montreux (1961). (b) C.C.I.R. Doc. XI/33 (Japan), Bad Kreuznach, 1962. 11. R a in g e r , P. An electronic line-standards converter. I.E.E. Journal, Electronics and Power, 165 (May, 1964). 12. R a in g e r , P. and R o u t , E. R . Television standards converters using a line store. Proc. I.E.E., 113, 9, 1437-1457 (September, 1966). 13. C.C.I.R. Doc. XI/141 (Japan), 1963-1966. 14. C.C.I.R. Doc. XI/132 (United Kingdom), 1963-1966. 15. C.C.I.R. Doc. XI/17 (Japan), 1966-1969. 16. C.C.I.R. Doc. XI/41 (U.S.S.R.), 1966-1969. 17. R o u t , E. R. and D a v ie s, R. E. Electronic standards conversion for transatlantic colour television, JSMPTE, 77, 12-14 (1 January, 1969). 18. Jaeschke, F. Methoden zur Farbnormwandlung NTSC-PAL zwischen Fernsehnormen unter- schiedlicher Vertikalfrequenz (Methods for NTSC-PAL colour-standards conversion between television standards with different vertical frequencies). NTZ, 177-181 (April, 1968). 19. Colour TV Standards converter. Wireless World, 73, 10, 476-477 (October, 1967). 20. D a v ie s , R. E. Full-screen TV standards converter. Wireless World, 75, 1399, 8-10 (January, 1969). 21. C.C.I.R. Doc. XI/171 (Japan), 1966-1969. 22. W e n d t, H. Ein elektro-optischer Normwandler fur Farbfernsehsignale (An electro-optical standards converter for colour television signals). NTZ, Heft 5, 281-285 (May, 1969). Rep. 477 — 82 —

REPORT 477 * TRANSCODING OF COLOUR TELEVISION SIGNALS FROM ONE COLOUR SYSTEM TO ANOTHER

(Study Programme 2-1 A /11)

(1970) The different colour systems now being used on the various 625-line television standards require, for international exchange of colour television programmes, that, when the colour television system employed in the originating country differs from that of the receiving country, a means be provided of changing the colour television system. Since no change of line or field frequency is necessary but only a change in the coding of the colour information, the process for effecting this change has been given the name of “ transcoding” . A considerable amount of work on the design and production of transcoding equipment has been carried out in several countries. For the benefit of workers in this field of activity, a bibliography follows.

B ibliography

1. Transcoding NTSC-PAL-NTSC. E.B.U. Doc. Com.T(E) 136 (October, 1964). 2. Transcoding NTSC-PAL-NTSC. E.B.U. Doc. Com.T(E) 148 (December, 1964). 3. B r u c h , W. Ein neues Verfahren zur zentralen Phasenfehlerkorrektur eines PAL Farbfernseh- signals (PAL-IN-PAL Transcoder). (A new approach to centrally correcting the phase of PAL colour television signals (PAL-IN-PAL Transcoder)). Telefunken-Zeitung, Vol. 37, 2 (1964). 4. B r u c h , W. A new approach to centrally correcting the phase of PAL colour TV signal (PAL PAL transcoder). Rundfunktechnische Mitteilungen, Vol. 9, 4 (1965). 5. Transcoding between the PAL and NTSC colour television systems. BBC Research Department, Tech. Memo. T 1084. 6. Steele, F. H. The transcoding of colour television signals. Television Society Journal, Vol. 11, 2 (April-June, 1965). 7. Report on transcoding. E.B.U. (Sub-Group 1) Com.T(E) 209 (November, 1965).

8 . Requirements for line frequency stability when transcoding SECAM-PAL. E.B.U. Com.T(E) 212, Institut fur Rundfunktechnik. 9. C a s t e l l i , E. Standards conversion and chrominance transcoding problems in the exchange of television programmes. IEEE Transactions, Broadcast and television receivers, Vol. BTR-12, 2 (May, 1966). 10. W a ts o n , S. N. A survey of colour transcoding. IEEE Transactions, Broadcast and television receivers, Vol. BTR-12, 2 (May, 1966). 11. Jaeschke, F. and W e n d t, H. A transcoder for conversion of SECAM colour television signals into the PAL system. Radio-Mentor Electronic, 34 (1968). 12. W e n d t, H. Method for separation of luminance and chrominance signals in transcoding SECAM- PAL. NTZ, 21, 4, 182-185 (1968). 13. J a e sc h k e , F. Methods for colour signal conversion NTSC-PAL between television standards of different picture frequencies. NTZ, 21, 4, 177-181 (1968). 14. C.C.I.R., Doc. XI/191 (France), 1966-1969.

* This Report was adopted unanimously. — 83 — Rep. 313-2

SECTION 11C: PICTURE QUALITY AND THE PARAMETERS AFFECTING IT

RECOMMENDATIONS AND REPORTS

Recommendations

There are no Recommendations in this section.

Reports

REPORT 313-2 * ASSESSMENT OF THE QUALITY OF TELEVISION PICTURES (Question 3-1/11)

(1959 - 1963 - 1966 - 1970)

It appears that during recent years extensive studies have been made in many labora tories on the assessment of the quality of television pictures and the respective methods of measurement, both for monochrome and colour television. Since it would appear that these studies cannot yet be considered to be concluded, it seems appropriate, with a view to facilitat ing future work, to give a list of documents and publications bearing on this question. Such a list would serve, both to avoid duplication of work and to enable comparisons to be made with results already found elsewhere. It may be extended to include subsequent publications on this subject and would be a valuable aid, within the scope of Question 3 -1 /1 1 , in arriving at suitable standard methods for measuring the various kinds of picture distortion in television.

Bibliography relating to Question 3-ljll 1. C.C.I.R. Doc. XI/3, Moscow, 1958. A simple test picture for the assessment of the quality of monochrome television pictures. 2. C.C.I.R. Doc. XI/11, Moscow, 1958. An equipment for electro-optical measurements of television image quality. 3. C.C.I.R. Doc. XI/12, Moscow, 1958. Method of measurement of interlacing quality on television receivers. 4. C.C.I.R. Doc. XI/24, Moscow, 1958. Direct measurement of noise on the receiver screen. 5. C.C.I.R. Doc. XI/25, Moscow, 1958. Apparatus for the measurement of signal-to-noise ratio in video signals. 6 . J e sty , L. C. Relation between picture size, viewing distance and picture quality. Proc. I.E.E., 105, B (February, 1958). 7. C.C.I.R. Doc. 39, Los Angeles, 1959. Measurement of random noise in television pictures. 8 . C.C.I.R. Doc. 124, Los Angeles, 1959. Method of measuring the numerical characteristics of gamma correctors. 9. C.C.I.R. Doc. 125, Los Angeles, 1959. Influence of the colour parameters of the television receiver on the quality of colour reproduction. 10. C.C.I.R. Doc. 126, Los Angeles, 1959. Effect of sub-carrier frequency on luminance. 11. C.C.I.R. Doc. 145, Los Angeles, 1959. Assessment of the luminance and chrominance of tele vision pictures. 12. C.C.I.R. Doc. 383, Warsaw, 1956 and Doc. XI/18, Bad Kreuznach, 1962. Measurement of the quality of television pictures.

* This Report was adopted unanimously. Rep. 313-2 / — 84 —

13. C.C.I.R. Doc. XI/22, Bad Kreuznach, 1962. Methods of measuring the basic parameter of a television signal. 14. C.C.I.R. Doc. XI/30, Bad Kreuznach, 1962. Psychological aspects of quality assessment. 15. C.C.I.R. Doc. XI/29, Bad Kreuznach, 1962. Ratio of the wanted to the unwanted signal in television. 16. C.C.I.R. Doc. XI/61, 1963-1966. Automatic documentary recording of the video signal wave form. (Refers to Krivosheev, M. I.: Fundamentals of television measurements, Moscow, Publishing-House “Sviaz” (1964). 17. C.C.I.R. Doc. XI/62, 1963-1966. Measurement of signal-to-r.m.s. noise by means of an oscillo graph. > 18. C.C.I.R. Doc. XI/63, 1963-1966. Automatic measurement of the quality of television signals during the transmission of the monochrome television programme. 19. (a) C.C.I.R. Doc. XI/16, 1963-1966. Subjective assessment of the quality of television pictures. (Refers to P r o s s e r , R. D., A l l n a t t , J. W. and L ew is, N. W., “Quality grading of impaired television pictures”, Proc. I.E.E., 112, 491-502 (March, 1964)). (b) A l l n a t t , J. W. and P r o s s e r , R. D. Subjective quality of television pictures impaired by long- delayed echoes. Proc. I.E.E., 112, 487-492 (March, 1965). (c) P r o s s e r , R. D. and A l l n a t t , J. W. Subjective quality of television pictures impaired by random noise. Proc. I.E.E., 112, 1 0 99-1102 (June, 1965). (d) L ew is, N. W. and A l l n a t t , J. W. Subjective quality of television pictures with multiple impairments. Electronics Letter, 1, 187-188 (September, 1965). (e) A l l n a t t , J. W. Subjective quality of colour television pictures impaired by gain and delay inequalities between the luminance and chrominance channels. Proc. I.E.E., 112, 1819-1824 (October, 1965). (f) A l l n a t t , J. W. and P r o s s e r , R. D. Subjective quality of colour-television pictures impaired by random noise. Proc. I.E.E., 113, 551-557 (April, 1966). (g) A l l n a t t , J. W. and B r a g g , E. J. W. Subjective quality of television pictures impaired by sinewave noise and low-frequency random noise. Proc. I.E.E., 115, 371-375 (March, 1968). (h) L ew is, N. W. and A l l n a t t , J. W. Subjective and objective impairments in television pictures. I.E.E. Conference Publication No. 46. 2.1.1. - 2.1.5. (1968). (j) C o r b e tt, J. M., T a y lo r , J. R. and A l l n a t t , J. W. Subjective quality of colour-television pictures impaired by video-crosstalk. Proc. I.E.E., 116, 181-184 (February, 1969). 20. C.C.I.R. Doc. XI/31, 1963-1966. Subjective assessment of the quality of television pictures. (Refers to a paper published: Grosskopf, H.: Guide values for the adjustment of optimum conditions for viewing television pictures, NTZ-CI, 6 , 262-266 (1963)). 21. C.C.I.R. Doc. XI/149, 1963-1966. Subjective assessment of the quality of television pictures in the international exchange of programmes. 22. C.C.I.R. Doc. XI/37 (Federal Republic of Germany), 1966-1969. Universal electronic test pattern for monochrome and colour television transmission. 23. C.C.I.R. Doc. XI/39 (U.S.S.R.), 1966-1969. Automatic documentary recording of the video signal waveform. (Refers to Krivosheev, M. I., M a r e i n , R. L. and K u z m in , V. I., Tekhnika kino i televideniya, 3 (1968)). 24. C.C.I.R. Doc. XI/40 (U.S.S.R.), 1966-1969. Measurement of detail contrast in television pictures. (Refers to Olshvang, E. V., Tekhnika kino i televideniya, 3, 51-54 (1967)). 25. C.C.I.R. Doc. XI/56 (France), 1966-1969. Test pattern for the adjustment and servicing to SECAM-type colour receivers.

26. G e d d e s , W. K. E. The relative impairment produced by random noise in 405-line and 625-line television pictures. E.B.U. Review, A-Technical, 78, 46-48 (April, 1963). 27. C.C.I.R. Doc. XI/203 (Italy), 1966-1969. Effect of noise on picture quality for colour television signals using the PAL system. — 85 — Rep. 404-1

REPORT 404-1 *

DISTORTION OF TELEVISION SIGNALS DUE TO THE USE OF VESTIGIAL-SIDEBAND TRANSMISSION (1966 - 1970) For several years the O.I.R.T. has studied questions connected with the investigation of distortions of television signals in vestigial-sideband transmissions. Several contributions t to this problem have already been submitted by the O.I.R.T. to the C.C.I.R. This document provides a synthesis of all information in the documents enumerated in Report 404 (1966) supplemented by new data based on studies carried out by the O.I.R.T.

1. Introduction

Vestigial-sideband transmission of television signals and their reception with receivers using demodulation with a Nyquist slope give rise to different kinds of distortion: — linear distortion due to group-delay differences in the receiver circuits, both along the Nyquist slope and in relation to the necessary attenuation on sound carrier of the lower adjacent channel; — non-linear distortion due to the envelope demodulation, in the form of quadrature dis tortion, and to crosstalk between the luminance and the chrominance signals.

These distortions result in the deterioration of the quality of the received television picture. Theoretical and practical investigations have been recently carried out in many countries with the aim, on one hand, of obtaining a quantitative picture of the distortion of television signals due to the use of vestigial-sideband transmission and, on the other hand, of finding methods of reducing this distortion as well as of determining the degree of the picture quality improvement as perceived by viewers. Such improvement can be ensured by the correction of distortion or the selection of the optimal width of the lower sideband and the steepness of the Nyquist slope.

2. Analysis of the television signal distortion

The distortion of television signals, arising in the vestigial-sideband transmission, depends on several factors such as the steepness of the Nyquist slope (i.e. the relative width of the vestigial sideband), the modulation depth, and the position of the vision carrier on the Nyquist slope. These distortions can be presented either as depending on frequency, i.e. by the amplitude and group-delay characteristics, or as depending on time, by the transient characteristic.

The television signal distortion due to the vestigial-sideband transmission affects the build-up time (10-90%) of the transient characteristic, or causes voltage overshoots.

When analyzing the distortion by means of the approximated calculation method [8 , 17], the following conclusions can be drawn:

— the distortions increase with the modulation depth; — the build-up time diminishes with the decreasing steepness of the Nyquist slope (i.e. the increasing useful width of the vestigial sideband);

* This Report was adopted unanimously. Rep. 404-1 — 86 —

— the influence of the changes of the vision carrier position on the Nyquist slope with regard to the value of distortions depends, to a great extent, on the steepness of the Nyquist slope—it diminishes with the decreasing steepness; — the shift of the vision carrier on the Nyquist slope within 0 and - 1-5 MHz in relation to the nominal position generally tends to decrease the distortions (decreased build-up time and overshoots, improved symmetry of the transient characteristic). It can be presumed that in industrial receivers the Nyquist slope, within the established tolerances, can be approximated by straight lines. In this case the calculated results are highly accurate in practical conditions. Thus it follows that a further decrease of the steepness of the Nyquist slope will not result in an essential improvement of the video signal form. Similar results have been obtained by computer calculations. It is noted [9] that a change of the steepness of the Nyquist slope from 0-75 to 1 MHz does not lead to a perceptible decrease of distortions.

3. Establishment of tolerances for television signal distortion

Measurements of the frequency responses of television transmitters are usually effected between the transmitter input and the Nyquist demodulator output. In this case the measure ment results reflect the actual distortions of television signals at the receiving end. As mentioned above the characteristics can be presented as depending on time, or as depending on frequency. Investigations [10] have shown that transient characteristics are more useful, because they afford a result closer to the visible effect of the distortions on the received television picture. On the basis of the assessed picture quality, the admissible dis tortion value can be determined. Under such conditions the amplitude-frequency character istic is of lesser importance. Attention should be drawn to the fact that at present no methods are known enabling transformation of tolerances of characteristics in the time domain into tolerances of charac teristics in the frequency domain, and vice versa. Even so the danger exists that an equipment may have transient characteristics within the tolerances, while the amplitude-frequency characteristic exceeds the respective tolerances. Tests have also shown [10] that transmitter phase correction can be easily effected on the basis of the transient characteristic, the same results being obtained as on the basis of measurement of the group-delay characteristic. So far sufficient data for the establishment of tolerances of television signal distortions have not been obtained. From theoretical calculations [9] follows that the difference between the group-delay on the vision carrier frequency and that on the central video frequency - corresponding to a Nyquist slope of 0-75 MHz is approximately 150 ns. It has also been proved that the non-uniformity of group-delay higher than 50 ns in the vicinity of the vision carrier frequency causes considerable distortion of the transient characteristics. For measurements on a television transmitter with the Nyquist demodulator, it is pro posed to use adequate tolerance masks, determining the admissible deviations of the individual characteristics from nominal responses [15]. These masks determine separately the parameters of the transmitter and those of the Nyquist demodulator [16] as well as the parameters of the entire transmitter-demodulator channel. Theoretical calculations of T and IT sine-squared pulse distortions in the Nyquist demodulator have shown that the amplitude of IT sine-squared pulse at the demodulator output attains: — 80 % without demodulator phase correction,

:— 1 0 0 % with demodulator phase correction; — 87 — Rep. 404-1

and the amplitude of T sine-squared pulse: — 76% without demodulator phase correction, — 80% with demodulator phase correction, in relation to the input pulse amplitude.

It has also been calculated that the distortion of 4-43 MHz sub-carrier pulse with 20T sine-squared envelope, originating in the Nyquist demodulator, need not be taken into consideration and that the distortion at the base of the pulse does not exceed 3 % when applying phase correction to the demodulator. A 4. Investigation of possibilities for improving picture quality To improve the quality of television pictures, distorted due to the use of vestigial- sideband transmission, several investigations have been carried out along two basic lines: — pre-correction of distortions while maintaining the existing standards for the width of the vestigial sideband, and — broadening of the vestigial sideband. 4.1 Correction o f the television signal distortions Long-term investigations of the correction of television signal distortions have led to the conclusion that in this way a considerable improvement of the signal form can be obtained [11]. With this in view, both correction of linear distortions with the aid of phase filters and correction quadrature distortions were used on the transmitter. Measurements effected under laboratory conditions and on a number of transmitters have shown that television signal distortions can be almost entirely eliminated in this way. In relation to colour television signals the quadrature component causes two types of distortion: incorrect reproduction of the brightness of coloured areas, and phase modulation of the vision carrier, depending on the degree of modulation. It has been shown that the correction of quadrature distortions can entirely eliminate both effects. With the aim of confirming the measurement results of the correction of linear and quadrature distortions investigations of picture quality have been carried out on the basis of subjective tests [12]. The results of these measurements make it possible to establish the following: — the improvement of picture quality obtained by group-delay correction is greater than that obtained by quadrature correction, — after an optimal correction of both types of distortion no deterioration of the picture quality can be observed; — in re-broadcasting transmissions with two successive modulation and demodulation processes quadrature correction should be used. The usefulness of linear-distortion correction has been investigated in system L [13]. Some improvement of the transient characteristic has been obtained (decreased overshoots from 7% to 4% and decreased'streaking). A further improvement of the picture quality can be obtained by quadrature correction. 4.2 Broadening o f the vestigial sideband In order to verify the influence of broadening the vestigial sideband on the subjective picture quality assessed by viewers, investigations of the picture quality with 0-75 MHz and 1-25 MHz vestigial sideband transmissions have been carried out [14]. Investigations with the aid of various characteristic pictures have confirmed that most viewers note a better picture quality in the case of transmission with a broader vestigial sideband, the degree of improvement depending on the contents of the picture. Differences in quality were almost indiscernible only in pictures with low contrast and a small number of details. Rep. 404-1 — 88 —

As regards broadening of the vestigial sideband, the opinion has been expressed [15] that the reduction of the steepness of the Nyquist slope tends to decrease the non-uniformity of group-delay and the quadrature distortions, as well as the sensitivity of the receiver to heterodyne frequency variations. For channels in bands IV/V, 1-5 MHz is considered to be the optimum value. At the same time, attention has been drawn to the fact that broadening of the vestigial sideband decreases the protection between adjacent channels and that this is connected with transmitter network planning and the establishment of protection ratios.

B ibliography 1. C.C.I.R. Report 404. 2. C.C.I.R. Doc. XI/25 (Federal Republic of Germany), Bad Kreuznach, 1962. 3. H o p f, H. and D in s e l, S. Verbesserung der Ubertragungsqualitat des Fernseh-Restseitenband- verfahrens durch Einfuhrung einer Quadraturentzerrung (Improvement in quality of transmis sion of vestigial-sideband television signals by the introduction of quadrature distortion). Rund- funktechnische Mitt., Vol. 5, 272-280 (1961). 4. D in s e l, S. Neue Untersuchungen iiber die Entzerrung der Quadraturfehler von Fernsehsendern (New studies on the correction of quadrature errors of television transmitters). Rundfunktech- nische Mitt., Vol. 8 , 253-265 (1964). 5. D o b e s c h , H. and S u la n k e , H. Zeitfunktionen (Time series). VEB Verlag Technik (1965).

6 . S z a n t o , L. Frekvencne a prechodne charakteristiky vysokofrekvencneho televizneho kan&lu (Steady-state and transient characteristics of RF television channels). Slaboproudy obzor, Vol.25, 8 , 466-474 (1964). 7. D in s e l, S. Quadrature distortion correction for television vestigial-sideband transmission. Journal of the SMPTE, Vol. 75, 20-25 (1966).

8 . C.C.I.R. Doc. XI/28 (O.I.R.T.), 1963-1966. 9. C.C.I.R. Doc. XI/42 (Czechoslovak S. R.), 1963-1966. 10. C.C.I.R. Doc. XI/23 (O.I.R.T.), 1963-1966. 11. C.C.I.R. Doc. XI/2 (Federal Republic of Germany), 1963-1966. 12. C.C.I.R. Doc. XI/142 (Federal Republic of Germany), 1963-1966. 13. C.C.I.R. Doc. XI/178 (France), 1963-1966. 14. C.C.I.R. Doc. XI/25 (O.I.R.T.), 1963-1966. 15. O.I.R.T. Doc. TK-I1I-218. Erweiterung des unteren Seitenbandes der Fernsehubertragung (Broadening of the lower sideband in television transmission). 16. O.I.R.T. Doc. TK-III-211. Verzerrungen der Sinus2-Impulse im Nyquist-Demodulator (Distortion of sine-squared impulses in a Nyquist demodulator). 17. D o b e s c h , H. Der Einschwingvorgang eines Fernseh-Sedensystems (Overshoot in television transmission systems). Technische Mitteilungen des RFZ, Heft 4 (1966). — 89 — Rep. 405-1

REPORT 405-1 *

SUBJECTIVE ASSESSMENT OF THE QUALITY OF TELEVISION PICTURES (Study Programme 3-1 A/ll) (1966 - 1970) Table I gives an outline of the main features of some existing methods of assessing the quality of impaired television pictures under laboratory conditions. Reference should be made to the source material for fuller details of the methods. Table II describes two methods used for assessing the quality of pictures during pro gramme transmissions. The preferred method for the laboratory assessment of picture quality is proposed in the Annex. Five-grade scales Quality scales Note 1. — A Excellent Note 2. — 5 Excellent B Good 4 Good C Fair 3 Fair D Poor 2 Bad E Bad 1 Very bad Impairment scales Note 3. — 5 Imperceptible Note 4. — 1 Imperceptible (implied grade) 4 Perceptible but not annoying 2 Detectable 3 Somewhat annoying 3 Noticeable 2 Severely annoying 4 Objectionable 1 Unusable 5 Unsuitable for broadcast Comparison (fidelity) scale Note 5. — 1 Equal 2 Slightly different 3 Different 4 Very different 5 Extremely different Six-grade scales Quality scales Note 6. — 1 Excellent 2 Good 3 Fairly good 4 Rather poor 5 Poor 6 Very poor Note 7. — 1 Excellent: the picture is of extremely high quality, as good as you could desire. 2 Fine: the picture is of high quality providing enjoyable viewing; interference is perceptible. 3 Passable: the picture is of acceptable quality; interference is not objectionable.

* This Report was adopted unanimously. Rep. 405-1 — 90 —

4 Marginal: the picture is poor in quality and you wish you could improv e it; interference is somewhat objectionable. 5 Inferior: the picture is very poor but you could watch it; definitely objectionable interference is present. 6 Unusable: the picture is so bad that you could not watch it. Impairment scale Note 8. — 1 Imperceptible 2 Just perceptible 3 Definitely perceptible but not disturbing 4 Somewhat objectionable 5 Definitely objectionable 6 Unusable

Seven-grade scales Impairment scale Note 9. — 1 Not perceptible 2 Just perceptible 3 Definitely perceptible, but only slight impairment to picture 4 Impairment to picture, but not objectionable 5 Somewhat objectionable 6 Definitely objectionable 7 Extremely objectionable Comparison scale Note 10. — —3 Much worse —2 Worse — 1 Slightly worse 0 Same as + 1 Slightly better + 2 Better + 3 Much better Note 11. — These higher values of peak luminance can be used with 60-field systems. Note 12. — Doc. XI/149 (O.I.R.T.), 1963-1966, points out the need for subjective assessment of picture quality during an international programme exchange. The document provides instructions on how to carry out the assessment, and also a list of terms related to the parameters subjected to assessment. The operational experience gained during transmissions in the Intervision network shows that in spite of the variety of monitoring devices used, adequate agreement on the assessment of picture quality was achieved by the technical staff. Note 13. — The expression “light surround” is defined as the light visible to the observer from a plane or from behind a plane coincident with, and surrounding but not including, the viewing screen. It is provided over an area at least eight times the area of the monitor screen, or, in the case of adjacent monitors, over an area at least four times the total monitor screen area. T a b l e I Conditions for laboratory assessments

Reference U.K. [1] E.B.U., O.I.R.T. [3, 4] Fed. Rep. of Germany [2] Japan [5,6] U.S.A. [7] U.S.A. [8] Italy [9]

Observers Category Non-expert Non-expert Non-expert Non-expert Expert Non-expert Number 20-25 > 6 > 1 0 20-25 approx. 2 0 0 > 1 0 approx. 2 0

Grading scale Type Quality Impair Quality Com Impair Quality Com Impair: Quality Quality Impairment Comparison ment parison ment parison ment Number of grades 5 6 6 7 5 5 5 5 5 6 7 5 (Note 1) (Note 8 ) (Note 6 ) (Note 10) (Note 3) (Note 2) (Note 7) (Note 9) (Note 5)

Test pictures Number 4-8 5 > 5 > 3 2 -8 3-4 6

Viewing conditions Ratio of viewing 6 4-6 6 6 -8 6 -8 4 6 distance to picture height . Peak luminance on 50 41-54 50 Approx. 400 70 170 (mono 50 the screen (monochrome) chrome) (cd/m2) (2) 74-84 (colour) 34 (colour) (Note 11) (Note 11) (Note 11) Contrast range of Not Not specified 30/1 to 50/1 Not the picture specified specified

Luminance of <0-5 0-5 < 0-5 Approx. 5 2 Approx. 0-5 inactive tube (monochrome) screen (cd/m2) 0-7-2 (colour)

Luminance of 1 backcloth illuminant C Approx. 2-5 0) Not specified (cd/m2) O Room illumina 3 Not specified 6-5 tion, average (lx) Random Random sequence of Random Random Random Random

sequence of pictures and sequence of sequence of sequence of sequence of 405-1 Rep. Presentation pictures and impairments pictures and impairments impairments pictures and impairments impairments impairments

(l) For monochrome only. (2) 1 cd/ni2 = 1 nt = 3-14 asb = 0-29 ft-L. (3) Ambient luminance at the end of the room as seen by the viewer. Table II

Conditions for assessment during programme transmission

Reference O.I.R.T. [10] Canada [11]

Observers

Category Expert Expert Number 1 -2 1 -2

Grading scale Impairment Quality Impairment Type 6 6 5 Number of grades (Note 8 ) (Note 6 ) (Note 4)

Pictures

Type Television programmes Television programmes

Viewing conditions

Ratio of viewing distance to 4-6 4-6 picture height Angle of view, from a line normal to the face of the monitor < 30° Luminance, on the screen, at reference white (cd/m2) 70 ± 7 Chromaticity of the screen at reference white Illuminant D Luminance of the inactive tube Adapted to the ambient As low as practicable screen illumination Luminance of “light surround” 10-5 ± 3-5 (cd/m2) (Note 13) Chromaticity of “light surround” Illuminant D — 93 — Rep. 405-1

B ibliography

1. C.C.I.R. Doc. XI/16 (United Kingdom), 1963-1966 (refers to a published paper: P r o s s e r , R. D., A l l n a t t , J. W., and L ew is, N. W. Quality grading of impaired television pictures. Proc. I.E.E., Ill, 491-502 (March, 1964)). 2. C.C.I.R. Doc. XI/31 (Federal Republic of Germany), 1963-1966 (refers to Grosskopf, H. Guide values for the adjustment of optimum conditions for viewing television pictures. NTZ, 6 , 262-266 (1963); also, experience of Federal Republic of Germany, unpublished). 3. C.C.I.R. Doc. XI/33 (E.B.U.), 1963-1966. Report of the E.B.U. ad hoc Group on colour television, 2nd Edition (February, 1965). 4. C.C.I.R. Doc. XI/45 (C.C.I.R. Secretariat), 1963-1966 (refers to the joint report of E.B.U and O.I.R.T. on comparative tests of colour television pictures over long international circuits). 5. C.C.I.R. Doc. XI/140 (Japan), 1963-1966 (refers to the following bibliography): 5.1 Yamaguchi, Y. Application of electronic digital computer to psychometric experiments (in Japanese). J. Inst. Television Engrs., Japan, 18, 530-534 (1964). 5.2 Hiwatashi, K. et al. Subjective tone reproduction of television system and recommendation for density standard of television film (in Japanese). NHK Technical Journal, 16, 8-38 (1964). 5.3 H a s e g a w a , T. Viewing ratio and subjective sharpness of television pictures (in Japanese). Nat. Conv. Inst. Television Engrs., Japan (1965). 5.4 H a s e g a w a , T. et al. Optimal viewing distance as a function of television system bandwidth (in Japanese). Conv. Inst. Elec. Comm. Engers., Japan (1965). 5.5 O o sh im a, M. The human factor consideration of television (in Japanese). J. Inst. Tele vision Engrs., Japan, 19, 538-545 (1965).

6 . C.C.I.R. Doc. XI/155 (Japan), 1966-1969 (refers to the following bibliography): 6.1 T a d o k o r o , Y. et al. Experiments on viewing conditions of colour television pictures (in Japanese). NHK Giken Geppo, 11, 12 (December, 1968). 6.2 Audience Service Engineering Division of NHK: Investigation report about home viewing conditions of colour television pictures (in Japanese). Tokyo Dayori, 18, 3 (March, 1968). 6.3 Art Department of Nippon University: General investigation of colour television (in Japanese). (September, 1967). 7. C.C.I.R. Doc. XI/145 (U.S.A.), 1963-1966, which refers to: Fredendall, G. L . and B e h r e n d , W. L. Picture quality—Procedure for evaluating subjective effects of interference. Proc. IRE (June, 1960). 8 . C.C.I.R. Doc. XI/8 (U.S.A.), 1966-1969. 9. C.C.I.R. Docs. XI/45 and XI/181 (Italy), 1966-1969. 10. C.C.I.R. Doc. XI/46 (O.I.R.T.), 1966-1969. 11. C.C.I.R. Doc. XI/146 (Canada), 1966-1969. 12. C.C.I.R. Doc. XI/158 (France), 1966-1969. 13. C.C.I.R. Doc. XI/159 (France), 1966-1969. Rep. 405-1 — 94 —

ANNEX

PREFERRED METHOD FOR LABORATORY ASSESSMENT OF PICTURE QUALITY

1. Introduction A large amount of information has been collected about the methods used in various laboratories for the assessment of picture quality. Examination of these methods shows that there exists a considerable measure of agreement between the different laboratories about a number of aspects of the tests. It is therefore considered appropriate to propose a preferred method for the laboratory assessment of picture quality which, it is hoped, will be studied by the various laboratories and which could form a basis for a future Recommendation.

Before giving details of the preferred method it should be stated that the primary purpose of the assessment of picture quality is to attempt to ascertain the opinion of the non expert observer about the overall quality of a picture which has been subjected to one or more impairments and which is viewed under conditions which are more critical than average but which are not extreme. As tests with non-expert observers tend to be lengthy, it is often desirable that a quick test should be carried out by experts. In this case a smaller number of observers can be used and it may be convenient to use a n impairment scale as it is reasonable to ask an expert observer to concentrate his interests on a particular impairment, whereas it is not reasonable to ask a non-expert observer to do this. However, it should be noted that tests carried out with expert observers, using either a quality or an impairment scale, cannot be regarded as a substitute for tests carried out by non-expert observers.

A full discussion on the use of expert and non-expert observers and other aspects of picture quality assessment can be found in [1].

2. Details of preferred method

2.1 Number o f observers The number of non-expert observers should be equal to or greater than 20. For tests where expert observers are used, the number should be equal to or greater than 1 0 . In all cases the number and category of observers should be stated.

2.2 Grading scale For non-expert observers a five-point quality scale should be used. For expert observers either the five-point quality scale or a five-point impairment scale should be used.

The scales used should be as follows: Quality scale Impairment scale 5 Excellent 5 Imperceptible 4 Good 4 Perceptible but not annoying 3 Fair 3 Visible, slightly annoying 2 Poor ' 2 Annoying 1 Bad 1 Very annoying

It is recognized that to suit local customs some laboratories may wish to invert the order of the numbering or to replace the numbers with letters when an experiment is being carried out. However, it is proposed that the results should be transformed into the form given above. — 95 — Rep. 405-1

2.3 Test pictures Approximately five test pictures should be used. These should be chosen to be more critical than average pictures but not the most critical which can be found.

2.4 Viewing conditions The preferred viewing conditions are affected by the field frequency of the television system. The Table shows the conditions for systems with 50 and 60 fields per second.

Field frequency (fields/s) 50 60

Ratio of viewing distance to picture height 6 6

Peak luminance on the screen (cd/m2) (2) 50

Luminance of inactive tube screen (cd/m2) < 0-5

Luminance of backcloth (cd/m2) 0 • 0

Room illumination (lx) 0 0

(*) Requires further study. (2) 1 cd/m2 = 1 nt = 3-14 asb = 0-29 ft-L.

2.5 Presentation The pictures and impairments should be presented in random sequence with the proviso that the same picture should never be presented on two successive occasions with different levels of impairment.

3. Conclusion In view of the progress which has already been made in obtaining a standardized method of laboratory assessment of picture quality, and because of the urgency and import ance of this work, it is requested that Administrations should study these proposals. Their use is urgently recommended for the experiments which will be carried out during the next period of the C.C.I.R. in order that these proposals may form the basis of a Recommendation.

9 Rep. 409-1 — 96 —

REPORT 409-1 *

BOUNDARIES OF THE TELEVISION SERVICE AREA IN RURAL DISTRICTS HAVING A LOW POPULATION DENSITY (Recommendation 417-2) (1966 - 1970) Where television services are to be provided for a sparsely populated region, in which better receivers and antenna installations are likely to be employed than those considered in Recommendation 417-2, Administrations may find it desirable to establish the appropriate median field strength for which protection against interference is planned as low as:

Band I III

dB rel. 1 [TV/m + 46 + 49

These values refer to the field strength at a height of 10 m above ground level. In such areas, without co-channel interference, it is generally observed that the public begin to lose interest in installing television reception equipment when, in the case of band III transmissions, the median field strength falls below +40 dB rel. 1 +V/m at 10 m above ground level. The values given in this Report have been obtained from field investigations of the ser vice area limits and picture quality in rural districts of Australia (Doc. XI/168, 1963-1966).

* This Report was adopted unanimously. — 97 — Rep. 478

REPORT 478 *

GHOST IMAGES IN MONOCHROME TELEVISION

Re-radiation from masts in the neighbourhood of transmitting antennae (Study Programme 6A/11) (1970) When a television radiator is sited too close to another antenna structure “ghost” images displaced from the wanted picture can occur over a large proportion of the service area due to re-radiation of the transmissions from the other mast. These “ghosts” can be termed “permanent ghosts” since they cannot generally be reduced by the use of receiving antenna directivity except in the vicinity of the transmitting station. In this way, they are distinguished from “local ghosts” which may be seen only by viewers situated close to large re-radiating structures and which can sometimes be reduced by suitable orientation of a directional receiving antenna. It has been suggested that under good viewing conditions, “ghost images” will produce negligible impairment for a ratio of 32 dB or more between the direct and re-radiated signals. This figure applies where the time separation is 2 jjis or more and may be less for smaller time separations [1 , 2 ]. It has been established, as the result of theoretical studies and experimental work [3 , 4 ] that, where the reflecting structure is at least as high as the antenna, the level of the re-radiated signals decreases at a rate of about 3 dB for each doubling of the distance separating the masts. In bands I and III, this variation can be appreciably modified by ground reflection, which can increase it by as much as 6 dB, or reduce it. The Table gives the distances in kilometres at which the ratio between the direct and re-radiated signals is 32 dB neglecting the effect of ground reflection for different frequencies and different types of mast. It is assumed that the reflecting mast is at least 60 m higher than the transmitting antenna.

Frequency (MHz) 50 200 800

Polarization Vertical Horizontal Vertical Horizontal Vertical Horizontal

Cylindrical mast, 3 m dia meter 1-4 1-4 1-2 1-2 1-2 1-2

Triangular lattice mast. 3 m side, least favourable orientation 1-5 2-4 1-5 0-9 2-4 2-4

Square lattice mast, 2-5 m side, least favourable orien tation 2-4 2-4 2-9 1-2 1-7 1-7

The ratio of the direct and reflected signals is modified by the horizontal radiation pattern of the transmitting antenna.

* This Report was adopted unanimously. Rep. 478 — 98 —

B ibliography

1. C.C.I.R. Doc. XI/3 (United Kingdom,) 1966-1969. 2. M e r t z , P. Influence of echoes on television transmission. Journal of the SMPTE, Vol. 60, 572-596 (May ,1953). 3. A l l n a t t , J. W. and P r o s s e r , R. D. Subjective quality of television pictures impaired by long- delayed echoes. Proc. I.E.E., Vol. 112, 3, 487-492 (March, 1965). 4. H i l l , P. J. Measurements of re-radiation from lattice masts at VHF. Proc. I.E.E., Vol. Ill, 12, 1957-1968 (December, 1964). 5. K n i g h t , P. Re-radiation from masts and similar obstacles at radio frequencies. Proc. I.E.E., Vol. 114, 1, 30-42 (January, 1967). — 99 — Rep. 481

REPORT 481 *

RATIO OF WANTED-TO-UNWANTED SIGNAL IN TELEVISION

Subjective assessment of multiple co-channel interference (Question 4-1/11) (1970) 1. This Report summarizes some recent work in the United Kingdom on the subjective effect of a combination of several co-channel interfering signals of constant, but not necessarily equal, levels. The document does not consider the situation in which the signals vary appre ciably with time. It includes consideration of transmissions with very high carrier-frequency stability (precision offset) but not special cases where carrier frequencies might be phase- locked. The interferences are considered to be in one of two classes, viz., “related” and “unre lated” interferences. The related class only arises in cases involving transmitters with precision control of the carrier frequency, i.e. control with a precision of the order of 1 Hz. The laws proposed for related interferences apply to a group of interferences for which either: — the frequency offsets relative to the wanted signal are close to (n ± 1 /3) times line-frequency, where n is a small integer, but precisely adjusted for minimum visibility of interference; — the interfering signal frequencies, apart from those covered above, are equal to one another within a few Hertz. For example, two-thirds and five-thirds line-frequency precision offsets can be considered as being in the related class, and it is unimportant whether the offset frequency is above or below the wanted signal. Similarly, all precision zero offset interferences can be regarded as in the related class. On the other hand, all non-precision offset interferences are to be regarded as unrelated. In the cases where both related and unrelated interferences are present, the related inter ferences should first be added in accordance with the appropriate law; the two classes can then be added together as if they were single unrelated interfering signals. For the purpose of dealing with co-channel signals with different offsets it is convenient to measure the inter fering signals in terms of protected field strength defined below: If Rr = protection ratio (dB) applicable to the rth interfering signal for a given sub jective impairment

and Ir = level (dB rel. 1 ^V/m) of the rth interfering signal, then Pr = Rr + /. is the protected field strength (dB rel. 1 (FV/m) applicable to the rth interfering signal.

2. Unrelated interferences appear to combine according to a simple power-addition law:

r — n 0-1 i> = log10 £ lO0 1 / ’,

3. For impairment grades near grade 3-5 (using the scale given in Note 2 of Report 405-1) related interferences tend to follow a different law. From the limited experimental work,

* This Report was adopted unanimously. Rep. 481 — 100 —

it appeared that a (voltage) 1-5 law represented the method of combination at least as well as any other law. Such a law may be written :

r — n 0 075 P = log10 £ 10°-075i^ r =1

4. For certain types of calculation it may be easier to use the following law which was equally accurate for the cases covered by the experiments (up to seven interfering signals):

01 P = log! 1001 Px+ 2 ^ 10-01Pr

where Px is the protected field strength applicable to the largest interfering signal alone.

5. For low interference levels (corresponding to grade 2-5 or less on the six-point impairment scale) there was a trend for all types of interfering signals (related or unrelated) to combine by the simple power-addition law given in § 2 .

B ibliography

1. C.C.I.R. Doc. XI/135 (United Kingdom), 1966-1969. 2. Subjective assessment of multiple co-channel television interference. B B.C. Research Report RA-26 (1968).

v — 101 — Rec. 266

SECTION 1 ID: ELEMENTS FOR PLANNING

RECOMMENDATIONS AND REPORTS

Recommendations

RECOMMENDATION 266

PHASE CORRECTION OF TELEVISION TRANSMITTERS NECESSITATED BY THE USE OF VESTIGIAL-SIDEBAND TRANSMISSION

The C.C.I.R., (1959)

CONSIDERING (a) that the transmission of television signals using vestigial-sideband techniques gives rise to distortion; (b) that this distortion consists of linear distortions (in-phase errors) and non-linear distortions (quadrature errors); (c) that with average pictures, the depths of modulation are low and thus the non-linear dis tortion is less than the linear distortion; (d) that these linear distortions arise partly from the transmitter and partly in the receiver; (e) that due. regard has to be paid to future design and development of television receivers as well as to the differing degree of phase errors in existing receivers;

UNANIMOUSLY RECOMMENDS

1 . that linear pre-correction shall be introduced into the television picture transmitter, so as to compensate for that part of the linear distortion arising from the errors in the radiated signal;

2 . that the television picture transmitter may also introduce a correction to compensate for linear distortions arising in the receiver, but this correction shall not exceed one half of that necessary to compensate a receiver using normal minimum phase-shift networks and with an amplitude characteristic corresponding to the television standard concerned; 3. that the pre-correction allowed in § 2 applies only to frequencies between zero and up to approximately half the video bandwidth. Rec. 417-2 — 102 —

RECOMMENDATION 417-2

MINIMUM FIELD STRENGTHS FOR WHICH PROTECTION MAY BE SOUGHT IN PLANNING A TELEVISION SERVICE

The C.C.I.R. (1963 - 1966 - 1970)

UNANIMOUSLY RECOMMENDS 1. that when planning a television service in bands I, III, IV or V, the median field strength for which protection against interference is planned should never be lower than:

Band I III IV V

dB rel. 1 +V/m +48 +55 +65 * +70 *

These values refer to the field strength at a height of 10 m above ground level;

2. that the percentage of time for which the protection may be sought should lie between 90 % and 99%. Note 1. — In arriving at the figures shown in § 1, it has been assumed that, in the absence of inter ference from other television transmissions and man-made noise, the minimum field strengths at the receiving antenna that will give a satisfactory grade of picture, taking into consideration receiver noise, cosmic noise, antenna gain and feeder loss, are: +47 dB rel. 1 fxV/m in band I, +53 dB in band III, +62 dB * in Band IV and +67 dB * in band V. Note 2. — Further information concerning the planning of television services for sparsely populated regions is contained in Report 409-1. Note 3. — In a practical plan, because of interference from other television transmissions, the field strengths that can be protected will generally be higher than those quoted in § 1 and the exact values to be used in the boundary areas between any two countries should be agreed between the Administrations concerned.

* The values shown for bands IV and V should be increased by 2 dB for the 625-line (O.I.R.T.) system. — 103 — Rec. 418-2

RECOMMENDATION 418-2

RATIO OF THE WANTED-TO-UNWANTED SIGNAL IN MONOCHROME TELEVISION (Question 4-1/11)

The C.C.I.R. (1963 - 1966 - 1970)

UNANIMOUSLY RECOMMENDS that the protection ratios given in the Annex should be used for planning purposes.

ANNEX 1. Introduction The protection ratios quoted are considered to be acceptable for planning purposes for a small percentage of the time, not precisely defined, but assumed to be between 1 % and 1 0 %*. » Protection ratios for just perceptible interference would be some 10 to 20 dB higher. When making use of the protection ratios in planning, suitable allowance for fading is made by using field-strength curves appropriate to the percentage of time for which pro tection is desired, it being assumed that fading of the wanted signal is small, compared with that of the unwanted signal. The protection ratios quoted refer in all cases to the ratios at the input to the receiver, no account having been taken of the effect of using directional receiving antennae or of the advantage that can be obtained by using different polarization for transmission of the wanted and unwanted signals. The amplitude of a vision-modulated signal is defined as the r.m.s. value of the carrier at peaks of the modulation envelope, while that of a sound-modulated signal is the r.m.s. value of the unmodulated carrier, both for amplitude-modulation and for frequency-modulation. All the protection ratios quoted in this Annex refer to interference from a single inter fering source. The full advantage of offset operation can only be obtained if the carrier frequencies of the transmitters concerned are within ±500 Hz of their nominal values.

2. Interference within the same channel

2.1 Protection ratio when the wanted and unwanted signals have the same line-frequency 2.1.1 Carriers separated by less than 1000 Hz but not synchronized Protection ratio: 45 dB **. 2.1.2 Carriers separated by less than 50 Hz, but not synchronized Protection ratio reduced by 5 to 10 dB relative to the preceding case. 2.1.3 Nominal carrier frequencies separated by lj3, 2/3, 4/3 or 5/3 o f the line-frequency Protection ratio: — for 405-line system: 35 dB; — for 525-line system: 28 dB; — for 625- and 819-line systems: 30 dB.

* The question of the protection necessary when interference is present for a large percentage of the time is considered in Report 479. ** This value may be reduced by about 20 dB for the 525-line system, if a carrier separation of a few hundred hertz is maintained ht an appropriate multiple of the frame frequency with a variation in carrier-frequency difference less than T5 Hz. Rec. 418-2 — 104 —

These values may be reduced to 28 dB, 20 dB and 20 dB respectively, if a carrier separa tion equal to an appropriate multiple of the frame frequency can be maintained; the line-frequency should be kept constant to within 5 x 10~6 and each transmitter should have a frequency tolerance of not more than ±2-5 Hz. The 20 dB value is at present valid for the 525- and 625-line systems when there is one unwanted transmitter. Under these conditions, the ratio between the wanted and unwanted sound signals will also be 20 dB, and this is permissible only if the offset is at least 5/3 of the line-frequency for frequency-modulated sound (see § 6.1), or above the audio-frequency range for amplitude-modulated sound (see § 6 .2 ). 2.1.4 Nominal carrier frequencies separated by 1/2 or 3/2 o f the line-frequency Protection ratio: — for 405-line system: 31 dB; — for 525-, 625- and 819-line systems: 27 dB.

2.2 Protection ratio for the picture signal when the wanted and unwanted signals have different line-frequencies 2.2.1 Carriers separated by less than 1000 Hz, but not synchronized Protection ratio: 45 dB. 2.2.2 Carriers separated by less than 50 Hz, but not synchronized Protection ratio reduced by 5 to 10 dB relative to the preceding case. 2.2.3 Nominal carrier frequencies separated by 6-3 kH z Protection ratio between a 625-line system and an 819-line system: 30 dB.

3. Adjacent-channel interference

Throughout this section, fairly conservative values have been chosen to take account of the divergence in performance between different types of television receivers and to allow for the possible introduction of colour.

3.1 Lower * adjacent-channel interference — VHP bands The worst interference on the picture signal from another signal using the same standard results from the sound signal in the lower * adjacent channel. The figures below relate to the cases where the separation between the wanted vision carrier frequency and the unwanted sound carrier frequency is 1 -5 MHz and the ratio between the unwanted vision and unwanted sound powers is 7 dB. The ratios are expressed in terms of the wanted and unwanted vision signals.

Protection ratio: — for frequency-modulated sound carrier (except System N): — 6 dB; — for amplitude-modulated sound carrier (System N): —10 dB; — for amplitude-modulated sound carrier: —2 dB.

3.2 Lower adjacent-channel interference — UHFbands

Protection ratio: — for the 525-line system in a 6 MHz channel: — 6 dB.

For the various 625-line systems proposed for use in 8 MHz channels in the UHF bands, the table below gives the protection required by a signal on any system against a lower adjacent-channel signal of the same or any of the other standards. The protection ratios quoted are those to be applied between the wanted and unwanted vision signal levels.

* Upper for the 405-line standard, since the vestigial sideband lies above the vision carrier-frequency. — 105 — Rec. 418-2

Protection ratio (dB) for a Interfering signal wanted-signal standard: Vision/sound power standard ratio (dB) for (See Report 308-2) interfering signal G H I K i1) L

G — 6 - 6 - 6 - 6 - 6 7

H — 6 - 6 - 6 - 6 - 6 7

I - 6 - 6 - 6 (2) - 6 +3(2) 7

K - 6 + 16 + 16 - 6 + 16 7

L - 4 + 18 + 18 - 4 + 18 9

(1) Administrations using system K in the VHF bands are studying the possibility of broadening the vestigial sideband to 1 -25 MHz for use in the UHF bands without changing the other parameters of the systems. In this case, the protection ratios required for system K would be the same as those quoted for the 625-line system L.

(2) The values for systems / and L are different in this case, because receivers for system I will contain a sound trap giving additional rejection at the frequency of the interference.

Note. — When an interfering frequency-modulated sound signal is offset, during quiescent periods, relative to the wanted vision signal by a frequency equal to a multiple of the line- frequency plus or minus about one-third line-frequency, the protection ratio may be reduced by 6 dB. For an interfering amplitude-modulated sound signal with the carrier offset in a similar way the reduction may be greater.

3.3 Upper * adjacent-channel interference — VHF and UHF bands

Protection ratio: — for system K: 4 dB; — for system N: —10 dB — for all other systems: —12 dB.

4. Overlapping-channel interference

Figs. 1 to 9 give protection ratios for the 405-, 525-, 625- and 819-line systems when a CW signal of the carrier of an interfering sound or vision signal lies within the channel of the wanted transmission. When the difference between the carrier-frequencies of the wanted and unwanted signals is large and it is desired to use offset to reduce the necessary protection ratio, the line-frequency of the wanted signal must be controlled to within 5 parts in 106. Where it affects the result, the ratio of vision power to sound power is assumed to be 9 dB for system L, 3 dB for system M and 7 dB for the other systems.

* Lower, for system A in the VHF bands. Rec. 418-2 Rec. Protection ratio (dB) Protection ratio (dB) Protection ratio (dB) 3 2 1 1 3 5 7 9 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 2 3 2 0 1 2 - 4 5 6 - 8 - -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 6 7 8 9 -10 -9 -8 -7 -6 5 - 4 - 3 - 2 - 1 - 0 1 rqec sprto (MHz) separation Frequency Frequency separation (MHz)separation Frequency Frequency separation (MHz)Frequency separation 16 — 106 — F F F gure r u ig gure r u ig gure r u ig 3 2 1 — 107 — Rec. 418-2

F ig u r e 1

System A. Protection from vision-signal interference

In all cases in this figure, the ratios quoted are those between the wanted and the unwanted vision levels. Curve a — Interference to vision from a 405-, 625-, or 819-line vision signal with no special control of the nominal frequency difference between the carriers of the wanted and unwanted signals. Curve b — Interference to vision from a 405-, 625-, or 819-line vision signal when the nominal frequency difference between the carriers of the wanted and unwanted signals is a multiple of the line frequency (10 125 Hz) plus or minus 3 to 5 kHz. If the nominal frequency difference is 1/2 or 3/2 of the line frequency, a protection ratio of 31 dB may be accepted (see § 2.1.4). Curve d — Interference to sound signal from a 405-, 625-, or 819-line vision signal.

F ig u r e 2

System A. Protection from CW or sound-signal interference

In all cases in this figure, the ratios quoted are those between the wanted vision and the unwanted sound levels. Curve e — Interference to vision from a CW or frequency-modulated sound signal with no special control of the nominal frequency difference between the carriers of the wanted and unwanted signals. Curve / — Interference to vision from an amplitude-modulated sound signal with no special control of the nominal frequency difference between the carriers of the wanted and unwanted signals. Curve g — Interference to vision from a frequency-modulated sound signal when the nominal frequency difference between the wanted-signal carrier and the interfering-sound carrier, during quiescent periods, is an odd multiple of half the line-frequency, 5062-5 Hz. Curve h — Interference to vision from an amplitude-modulated sound signal when the nominal frequency difference between the carriers of the wanted and unwanted signals is an odd multiple of half the line-frequency, 5062-5 Hz.

F ig u r e 3

System M. Protection from vision-signal interference

In all cases in this figure, the ratios quoted are those between the wanted and the unwanted vision signals. Curve a — Interference to vision from another 525-line vision signal with no special control of the nominal frequency difference between the carriers of the wanted and unwanted signals. Curve b — Interference to vision from another 525-line vision signal when the nominal frequency difference between the carriers of the wanted and unwanted signals is a multiple of the line-frequency (15-75 kHz) plus or minus one-third of the line-frequency (5-25 kHz). Curve d — Interference to sound signal from a 525-line vision signal. Rec. 418-2 Rec. Protection ratio (dB) Protection ratio (dB) Protection ratio (dB) 3 2 1 1 3 5 7 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 Frequency separation (MHz)separationFrequency (MHz)Frequencyseparation rqec sprto (MHz) separation Frequency 18 — 108 — F F F gure r u ig gure r u ig gure r u ig 5 4 6 10 — 109 — Rec. 418-2

F ig u r e 4

625-line system. Protection from vision-signal interference

In all cases in this figure, the levels quoted are those between the wanted and unwanted vision levels. The subscript numbers used on the curves indicate the various applications of the 625-line system: 1 — 625 lines; 2 — system 7; 3 — system K 4 — system L. Curves a — Interference to vision from 405-, 625-, or 819-line systems vision signal, with no special control of the nominal frequency-difference between the carriers of the wanted and unwanted signals. Curves b — Interference to vision from a 625-line vision signal when the nominal frequency difference between the carriers of the wanted and unwanted signals is a multiple of the line-frequency (15 625 Hz), plus or minus one-third of the line-frequency (5208 Hz). Curves c — Interference to vision from a 625-line vision signal when the nominal frequency difference between the carriers of the wanted and unwanted signals is an odd multiple of half the line- frequency (7812-5 Hz). Curves d — Interference to sound from a 625-line vision signal.

* If a vestigial sideband of 1-25 MHz is used in system K, curves at and bt should be used instead of curves a3 and b3 and curve c3 is no longer valid.

F ig u r e 5 625-line system. Protection from CW or sound-signal interference

In both cases in this figure, the ratios quoted are those between the wanted vision and the unwanted sound levels. The subscript numbers are used on the curves to indicate the variations applicable to the various 625-line systems as follows: 1 — 625-lines; 2 — system 7; 3 — system K *; 4 — system L. Curves e — Interference to vision from a CW or frequency-modulated sound signal, with no special control of the nominal frequency difference between the carriers of the wanted and unwanted signals. For amplitude-modulation of the interfering sound signal, the protection ratios should be increased by 4 dB. In the case of curve

* If a vestigial sideband of 1 '25 MHz is used in system K, curves e4, and gt should be used instead of curves es and g„.

F ig u r e 6 System E. Protection from vision-signal interference

In all cases in this figure, the ratios quoted are those between the wanted and unwanted vision levels. Curve a — Interference to vision from a 405-, 625-, or 819-line vision signal with no special control of the nominal frequency difference between the carriers of the wanted und unwanted signals. Curve b — Interference to vision from an 819-line vision signal, when the nominal frequency difference between the wanted and unwanted signal carriers is a multiple of the line-frequency (20 475 Hz), plus or minus one-third of the line-frequency (6825 Hz). Curve d — Interference to the sound signal from a 405-, 625- or 819-line vision signal. e.482 10 — 110 — 418-2 Rec. Protection ratio (dB) Protection ratio (dB) Protection ratio (dB) 3 2 1 1 3 5 7 9 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 3 2 1 1 3 5 7 9 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 Frequency separation (MHz)Frequencyseparation Frequency separation (MHz)Frequencyseparation Frequency separation (MHz) separation Frequency F F F gure r u ig gure r u ig gure r u ig 7 8 9 — I ll — Rec. 418-2

F ig u r e 7

System E. Protection from CW or sound-signal interference

In both cases in this figure, the ratios quoted are those between the wanted vision and unwanted sound levels. Curve e — Interference to vision from a CW or frequency-modulated sound signal, with no special control of the nominal frequency difference between the carriers of the wanted and unwanted signals. For amplitude-modulation of the interfering sound signal, the protection ratios should be increased by 4 dB. Curve g — Interference to vision from a frequency-modulated sound signal, when the nominal frequency difference between the wanted signal carrier and the sound carrier during quiescent periods is an odd multiple of half the line-frequency (10 237-5 Hz).

F ig u r e 8

Systems C and F. Protection from vision-signal interference

In all cases in this figure, the ratios quoted are those between the wanted levels of the vision and unwanted vision signals. Letters with a single prime are used for curves applying to System C. Letters with double primes are used for curves applying to System F. Curves a— Interference to vision from a 405-, 625-, or 819-line vision signal, with no special control of the nominal frequency difference between the carriers of the wanted and unwanted signals. Curves b— Interference to vision from a vision signal, having the same number of lines when the nominal frequency difference between the carriers of the wanted and unwanted signals is a multiple of the line-frequency (15 625 or 20 475 Hz), plus or minus one-third of the line-frequency (5208 or 6825 Hz). Curves d— Interference to the sound signal from a 405-, 625-, or 819-line vision signal.

F ig u r e 9

Systems C and F. Protection from CW and sound-signal interference

In all cases in this figure, the ratios quoted are those between the levels of the wanted vision and the unwanted sound signals. * Letters with a single prime are used for curves applying to System C. Letters with double primes are used for curves applying to System F. Curves e — Interference to vision signal from a CW or frequency-modulated sound signal, with no special control of the nominal frequency difference between the carriers of the wanted and unwanted signals. When the interfering sound signal is amplitude-modulated, the protection ratios should be increased by 4 dB. Curves g — Interference to vision signal from a CW or frequency-modulated sound signal, when the nominal frequency difference between the carrier of the wanted signal and the sound carrier, during quiescent periods, is an odd multiple of half the line-frequency (7812-5 or 10 237-5 Hz). Rec. 418-2 — 112 —

5. Second channel (image channel) interference

The protection ratio required depends upon the intermediate frequency used and upon the second channel rejection of the receiver. For the purpose of planning it may be assumed that the second channel rejection of receivers will not be less than 40 dB except in receivers for the O.I.R.T. systems D and K when it will not be less than 30 dB.

6. Protection ratios between sound signals

(The ratios quoted are those between wanted and unwanted sound signals.)

6.1 Wanted and unwanted sound signals frequency-modulated Protection ratio: — for carriers separated by less than 1000 Hz: 28 dB; — for carriers separated by 5/3 of the line-frequency: 20 dB.

6.2 Wanted and unwanted sound signals amplitude-modulated Protection ratio: — for carriers separated by frequency below the audio range: 30 dB; — for carriers separated by frequency within the audio range: 40 dB; — for carriers separated by frequency above the audio range: 15 dB.

6.3 Wanted-sound signal amplitude-modulated, unwanted-sound signal frequency-modulated Protection ratio: — for carriers separated by frequency below 1000 Hz: 40 dB; — for carriers separated by 25 kHz: 30 dB; — for carriers separated by 50 kHz: 12 dB.

6.4 Wanted-sound signal frequency-modulated, unwanted-sound signal amplitude-modulated Protection ratio: 30 dB. — 113 — Rec. 419

RECOMMENDATION 419

DIRECTIVITY OF ANTENNAE IN THE RECEPTION OF BROADCAST SOUND AND TELEVISION

The C.C.I.R. (1963)

UNANIMOUSLY RECOMMENDS that the characteristics of directivity of the receiving antennae of Fig. 1 can be used for planning broadcast sound or television service in bands I to V. Note 1. — It is considered that the discrimination shown will be available at the majority of antenna locations in built-up areas. At clear sites in open country, slightly higher values will be obtained. Note 2. — The curves in Fig. 1 are valid for signals of vertical or horizontal polarization, when both the wanted and the unwanted signals have the same polarization. Note 3. — The Special Regional Conference, Geneva, 1960, and the European VHF/UHF Broad casting Conference, Stockholm, 1961, did not take the directional characteristics of antennae into consideration for sound broadcasting.

-5

PQ - 1 0 T3

-2 0 O' 10' 20’ 30 40' 50' 60' 70* 80' 180' Angle relative to direction of main response

F ig u r e 1 ■ Discrimination obtained by the use of directional receiving antennae in broadcasting (The number of the broadcasting band is shown on the curve) Rep. 122-1 — 114 —

11D : Reports REPORT 122-1 * ADVANTAGES TO BE GAINED BY USING ORTHOGONAL WAVE POLARIZATIONS IN THE PLANNING OF BROADCASTING SERVICES IN BANDS 8 (VHF) AND 9 (UHF) Sound and television (Question 101) (1956 - 1959 - 1970) Investigations have been conducted in several countries to ascertain the advantages which can be obtained in sound and television broadcasting by using polarization discrimina tion in reception. The results of extensive studies made in Europe by the Federal Republic of Germany, France, Italy and the United Kingdom and also in the United States of America, have been made available in documents at Warsaw, 1956 and Geneva, 1958; and a reason ably definite answer may now be given to the question.

1. Band 8 (VHF)

In this band of frequencies, between 30 and 300 MHz, the median value of discrimina tion that can be achieved at domestic receiving sites by the ^ use of orthogonal polarization may be as much as 18 dB, and under these conditions, the values exceeded at 90% and 10% of the receiving sites are about 10 dB and 25 dB respectively. The values of discrimination are likely to be better in open country and worse in built-up areas or places where the receiving antenna is surrounded by obstacles. For domestic installa tions in densely populated districts, the median values of 18 dB will usually be realized only at roof level; and this value may be reduced to 13 dB or less at street level.

No significant changes in the polarization of waves in band 8 due to transmission through the troposphere have been observed over distances exceeding 200 km. Furthermore, there have been no reports of systematic changes in polarization effects with frequency in the metric band, neither with distance nor with type of terrain. It must be emphasized, however, that to realize the discrimination ratios mentioned above, certain precautions are necessary at both the transmitting and receiving installations; cases have been reported in which, for a transmitter of horizontally polarized waves, some 7 % of the radiated power was vertically polarized. It is clear that if the best discrimination is to be obtained for co-channel operation, the transmitters and antenna systems must be designed and installed so as to radiate as much as possible of the total power on the assigned polari zation. In the same way, to achieve the desired discrimination at the home receiving installation, the reception of the undesired orthogonally polarized waves on the antenna feeder and on • the receiver itself must be reduced to the minimum practicable value.

2. Band 9 (UHF)

Experiments have been conducted in the United Kingdom using horizontally polarized radiation on a frequency of about 500 MHz. Systematic measurements were made to determine the polarization discrimination at typical urban and rural sites, at distances up to about 55 km from the transmitter. The results showed that the discrimination obtained is

* This Report was adopted unanimously. — 115 — Rep. 122-1

similar to that already described above for frequencies in band 8 (VHF), although the factor exceeded for 90% of the receiving sites was only 8 dB (as compared with 10 dB for band 8 (VHF)). It is to be noted, however, that the transmitting antenna in use had considerable directivity, and there was a marked decrease in the polarization discrimination for directions of reception some 40° away from the direction of maximum radiation.

As in band 8 , care is necessary to ensure that the transmitter and receiver respectively do not emit or receive radiation of the undesired polarization. Apart from this, however, experience indicates that in band 9 (UHF), the use of horizontal polarization offers advantages, because of the greater directivity obtainable at the receiving antennae; this reduces the effect of reflected waves, particularly in town areas. The European Broadcasting Union, therefore, considers that frequency assignments in these bands should be based on the general use of horizontal polarization, though exceptions may be made in cases where ortho gonal polarization is necessary to achieve the desired protection.

3. Conclusion

From the studies described above, it is clear that the use of orthogonal polarization for broadcasting stations operating in the same frequency channel is of material assistance in discriminating against the reception of undesired signals. Worth-while advantages are obtainable over the whole band of frequencies from 40 to 500 MHz and within the normal broadcasting service ranges. From the uniformity of the discrimination obtained over these frequencies, it is considered to be almost certain that the advantages will extend to the top of the broadcasting band in band 9 at nearly 1000 MHz. This Report is considered to provide a sufficient answer to Question 101 for practical use, and this Question should now be concluded.

B ibliography

1. C.C.I.R. Docs. 267, 435 and 512, Warsaw, 1956. 2. C.C.I.R. Docs. V/l, V/6 , V/12, V/23 and V/27, Geneva, 1958.

/ Rep. 306-1 — 116 —

REPORT 306-1 * RATIO OF WANTED-TO-UNWANTED SIGNAL FOR COLOUR TELEVISION (Question 4-1/11) (1963 - 1966 - 1970) 1. Introduction The protection ratios required by system M and five variants (B, G, I, K, L) of the 625-line colour television system using a 4-43 MHz sub-carrier have been considered. For the purposes of planning, it may be assumed that the power in the chrominance channel at peaks of the colour modulation envelope cannot exceed a value 14 dB lower than the power in the main carrier at peaks of the modulation envelope.

2. Co-channel interference - protection ratios for mutual interference between any of the five systems B, G, I, K, L

2.1 Carriers separated by less than 1000 Hz, but not synchronized Protection ratio: 45 dB. 2.2 Nominal carrier frequencies separated by 1/3, 2/3, 4/3 or 5/3 o f the line frequency Protection ratio: 30 dB **. 2.3 Carriers separated by 1/2 or 3/2 o f the line frequency Protection ratio: 27 dB **. 2.4 For systems B, G, and I, the protection ratios are given in decibels in Table I:

T a b l e I

Offset (multiples of 0 l 2 3 4 5 6 7 8 9 10 11 12 1/12 line-frequency)

T 45 44 40 34 30 28 27 28 30 34 40 44 45 Transmitter stability C 52 51 48 43 40 36 33 36 40 43 48 51 52 ±500 Hz (non-precision offset) LP 60 60 57 54 50 45 42 45 50 54 57 60 60

T 30 34 30 26 2 2 22 24 2 2 2 2 26 30 34 30 Transmitter stability ±1 Hz C 36 38 34 30 27 27 30 27 27 30 34 38 36 (precision offset) LP 45 44 40 36 36 39 42 39 36 36 40 44 45

* This Report was adopted unanimously. ** If the wanted signal is system K or system L, and the interfering signal is system G, the protection ratio must be increased to 35 dB to avoid interference from the unwanted sound signal. — 117 — Rep. 306-1

T = tropospheric interference, 1 % to 10% of time (reference 30 dB at 8/12 line frequency) C = continuous interference (reference 40 dB at 8/12 line frequency) LP — limit of perceptibility The protection ratios given are valid up to about 50 kHz if multiples of the line frequency be added to the first line of Table I.

3. Adjacent-channel interference 3.1 Lower adjacent-channel interference The protection ratios are the same as those quoted for monochrome television in Recommendation 418-2, § 3.2. 3.2 Upper adjacent-channel interference The protection ratios are the same as those quoted for monochrome television in Recommendation 418-2, § 3.3.

4. Protection ratio curves

4.1 625-line NTSC system . The curves of Fig. 1 give the estimated protection ratios required by the four variants of the 625-line colour television signal, for interference from a CW or frequency-modulated sound signal. Letters G, I, K, L shown on the curves apply to the appropriate systems: G: 625-line system; I ; 625-line system; K: 625-line system *; L: 625-line system **. For frequency differences up to 2-85 MHz, the curves are the same as those for the monochrome 625-line systems (see Fig. 4, curves elf e2, ez, e4 of Recommendation 418-2). For higher frequency differences, the estimates are based upon the requirements for an adapted NTSC system. For interfering signals other than CW or frequency-modulated sound, no curves are given, as insufficient information is available. 4.2 625-line SECAM system The curve shown in Fig. 2 gives the estimated value of the necessary protection ratio required for the 625-line colour television signals (system L) using the SECAM system (described in Doc. XI/47, Bad Kreuznach, 1962), when the interfering signals are non modulated waves or frequency-modulated sound signals. 4.3 525-line NTSC system The curve shown in Fig. 3 gives the protection ratio required for 525-line colour tele vision signals using the NTSC system. 4.4 625-line PAL system, standards B and G The curve shown in Fig. 4 gives the protection ratios for the 625-line colour television signal, using the PAL system, standards B and G, for interference from a CW signal.

* If a vestigial sideband of 1 -25 MHz is used in a modified system K, curve K' should be used instead of curve K for frequencies located on the same side as the vestigial sideband. ** For frequencies located on the opposite side to the vestigial sideband, curve L refers to a system in which the colour information is transmitted by a process of quadrature modulation, in which double, instead of single-sideband modulation of the chrominance sub-carrier is used (±1.26 MHz relative to the sub-carrier). Rep. 306-1 — 118 —

The curves in Fig. 5 give the necessary protection ratio values for interference from a carrier negatively modulated by colour signals. Curve A refers to the case in which no particular relation between the nominal carrier frequencies of the wanted signal and of the interfering signal occurs. Curve B (non-precision offset) refers to the case in which the difference between the nominal frequencies of the two carriers is suitably related to the line frequency; the precision of the nominal carrier frequencies in this case is ± 500 Hz. Curve C (precision offset) refers to the case in which the difference between the nominal frequencies of the two carriers is suitably related to the line and field frequencies but with a ±1 to ±2-5 Hz precision of the nominal carrier frequencies and a stability of the line frequencies better than 1 x 1 0 -6. The optimum offset value depends upon the allocation of the carrier of the interfering signal in the channel of the wanted signal. There can be three different conditions with the following optimum offsets: — interfering co-channel signal: non-precision offset: from: +5/12 f n to +7/12/ h or from: -5/12 f H to -7 /1 2 f H precision offset: suitable frequency near to ± 8 / 1 2 f n or near to ± 7 / 1 2 fn — interfering signal in the frequency band which affects the luminance signal (from -1-5 MHz to + 3-5 MHz): offset: ± n fH + 1/2 f H — interfering signal in the frequency band which affects the chrominance signal (from +3-5 MHz to + 5 MHz): offset: n f H + 7/12 f H

B ibliography

1. C.C.I.R. Doc. XI/16 (Italy), 1966-1969. 2. C.C.I.R. Doc. XI/138 (Federal Republic of Germany), 1966-1969. 3. C.C.I.R. Doc. XI/187 (Italy), 1966-1969. Protection ratio (dB) Protection ratio (dB) Protection ratio (dB) Estimated protectionratios 625-line for colour systemadopted television 625 lines) for (NTSC systems 3 - 1 1 3 5 7 9 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 Estimated colour television625-lineprotection (systemratioL) SECAM a system for Protectionratios the colour525-line for televisionNTSC system Frequency differenceFrequency (MHz) Frequencydifference (MHz) Frequency differenceFrequency (MHz) 19 — 119 — F F F gure r u ig gure r u ig gure r u ig 3 2 1 Rep. 306-1 Rep. Protection ratio (dB) Protection ratio (dB) Rep. 306-1 Rep. 3 2 1 1 3 5 7 9 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 3 2 1 1 3 5 7 9 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 Estimated protectionratios the625-line for colour PAL television (standards andB G) system Estimated protectionratios the625-line for colour PAL television (standardssystemand G) B (Interferencevideo-modulated a signal)from (Interference from a CWsignal) (Interference a from Frequency differenceFrequency (MHz) Frequencydifference (MHz) 10 — 120 — F F gure r u ig gu e ur ig 4 5

— 121 — Rep. 307

REPORT 307 *

PROTECTION RATIOS FOR TELEVISION IN THE SHARED BANDS

Protection against radionavigation transmitters operating in the band 582 to 606 MHz (Question 4-1/11) (1963) 1. Introduction This Report is based on subjective tests carried out in Belgium, France and the United Kingdom. The results of some of these tests were used for planning purposes at the European VHF/UHF Broadcasting Conference, Stockholm, 1961 **, and, after some amendments, for the Special Agreement relating to the use of the band 582 to 606 MHz by the radionavigation service, Brussels, 1962. The tests were carried out with monochrome television signals, but the results were assumed to apply also to colour television signals. Further tests, however, are needed to confirm this assumption. It is considered that the protection ratios quoted in this Report should, in general, be afforded for at least 99% of the time. The protection ratios quoted apply to the signal at the input of the television receiver. The level of the television signal is expressed in terms of the power at the peak of the modula tion envelope and that of the radionavigation signal as the power at the peak pulse level.

2. Protection ratios required when the radionavigation signal falls within the passband of the television receiver It has been found that, when the radionavigation signal falls within the passband of the television receiver, the required signal-to-interference ratio is: 10 dB for systems with negative modulation, 15 dB for systems with positive modulation. The ratio is sensibly constant over the greater part of the passband of the television receiver, but decreases in accordance with the selectivity of the receiver as shown in Fig. 1. The protection ratios given in Fig. 1 do not relate to interference to the sound channel from signals of the radionavigation services. Further studies should be carried out on this subject.

3. Protection ratios required when the radionavigation signal falls outside the passband of the television receiver Reference should be made to Recommendation 418-2, § 5, for second-channel (image channel) interference. No information exists at present on adjacent channel interference. Note. — Other interference effects (intermodulation) are likely to occur if radionavigation stations, which in general use high peak powers and highly directional antennae, are situated near receiving locations, especially where the television signal is weak.

* This Report was adopted unanimously. ** However, at Stockholm, some delegates made reservations as to the prospect of fulfilling the technical criteria in the actual planning. Protection ratio (dB) 307 Rep. 3 - - 0 2 4 6 8 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 Protectionratio required aby picture signal againstradionavigationa signal thein582-606 band MHz Frequency separation with respect to the vision(MHz)the carrier withrespect Frequency to separation 12 — 122 — F gure r u ig 1 — 123 — Rep. 315-2

REPORT 315-2 *

REDUCTION OF THE CHANNEL CAPACITY REQUIRED FOR THE TRANSMISSION OF A TELEVISION SIGNAL

(Study Programme 11 A/11) (1963 - 1966 - 1970) 1. Studies on field rate and frame rate

Studies of human perception and of the rates at which the human brain is capable of acquiring information, which have been made since the establishment of existing television systems, have led to suggestions that the potential information rate of present television systems is too high. Since field rates of about 50 to 60 per second are required to prevent flicker over large uniform areas with present types of cathode-ray display, if frame rates rang ing from 1 2 to 16 per second are assumed to be satisfactory, it might be inferred that relatively simple systems using a 4/1 line-interlace or a combination of 2/1 line-interlace with a 2/1 dot-interlace would satisfy both conditions and require but half the present video bandwidth for equivalent picture detail. In fact, 4/1 line-interlace systems have been studied since 1941, but have been found to be very inferior to systems using 2 /1 line-interlace, as regards interline- flicker, line crawl and the serration of vertical line components in rapidly moving objects. Horizontal dot-interlace has also been examined and rejected as a means of economizing in bandwidth for monochrome television.

It is conceivable that new display devices, with improved storage characteristics, which would provide continuous presentation, might avoid flicker and reduce the need for line- or dot-interlace. A recent survey indicates that such displays are not likely to be available very soon for home use. The use of half-tone storage tubes, in conjunction with standards conver sion, would appear to offer some promise for relay purposes, but, up to the present time, this process has not proved to be attractive, because of the degradation of the picture which results. Further improvement in image-storage tubes may make this process practicable in the future.

2. Frame-to-frame redundancy

A second area of investigation which has been suggested is that of transmitting only the differences between successive frames. It is known that, on the average, a large percentage of the information merely repeats the information sent in previous frames. Conceivably, a system could be devised to use a lesser bandwidth and be capable of transmitting some percentage of probable frame sequences. In such a system, changes of information, at rates exceeding the potentialities of the system, would result in a delay in reproducing a complete change of scene in proportion to the reduction in bandwidth. Successive frames of many desired scenes will not in fact be redundant, because of motion of the subject or of the camera.

Nevertheless, there is some evidence that a human observer may not perceive the loss of some definition for a short time immediately following a complete change of scene. More over, changes in the picture, resulting from a movement of the subject or camera, are some times accompanied by a loss of definition due to limitations of the equipment.

Further study is required to determine acceptable values for parameters concerned.

* This Report was adopted unanimously. Rep. 315-2 — 124 —

3. Studies of frequency-interlacing systems

There is a further possibility of reducing the channel frequency bandwidth for the transmission of a television signal by splitting the frequency band, e.g. into a lower and an upper part and of inserting the information of the upper part into the lower one by suitable transposing processes. In this process, frequency offsetting techniques must be used so that the signal energy of the upper band falls into the gaps in the energy distribution of the signal of the lower band. Up to the present, the principal difficulty lies in the technical means for separating the interlaced information in the shared frequency band. However, the circuitry developed for compatible colour television now offers new possibilities (e.g. delay-line splitters developed for PAL colour receivers). Studies on these lines have shown some promise [12, 13].

B ibliography

1. C.C.I.R. Doc. 170 (U.S.S.R.), Geneva, 1963. 2. C.C.I.R. Doc. 19 (U.S.A.), Bad Kreuznach, 1962. 3. C.C.I.R. Doc. 32 (Japan), Bad Kreuznach, 1962.

4. S e y l e r , A. J. Channel capacity utilization of television relay links. Fortschritte der Hochfrequenztechnik, 5, 263-306 (1960).

5. S e y le r , A. J. The coding of visual signals to reduce channel capacity requirements. I.E.E. Monograph 5351s(July, 1962). (Published in Proc. I.E.E., Part C, 110 (1963).

6 . S e y l e r , A. J. The coding of visual signals to reduce channel capacity requirements. Proc. I.E.E., Part C, 109, 676-684 (1962). 7. C.C.I.R. Doc. XI/64 (U.S.S.R.), 1963-1966.

8 . L e b e d e v , D. S. and Zukkermann, I. I. Television and the information theory. Publishing House “Energia” (1965).

9. L e b e d e v , D. G. and L e b e d e v , D. S. Proc. Academy of Sciences, U.S.S.R., 11 (1964).

10. S e y le r , A. J. and Boudrikis, Z. L. Detail perception after scene changes in television displays. Trans. IEEE on information theory, Vol. IT-11, 31-43 (January, 1965). 11. C.C.I.R. Doc. XI/127 (Australia), 1963-1966. 12. C.C.I.R. Doc. XI/12 (Federal Republic of Germany), 1966-1969.

13. M a y e r , N. and M o l l , G. FBAS Farbfernseh-Obertragun giiber einen Kanal mit 2,5 MHz Bandbreite (Colour television transmission through a channel with a frequency bandwidth of 2-5 MHz). Radio Mentor-Electronic, 36-39 (1968). — 125 — Rep. 479

REPORT 479 *

PROTECTION RATIOS FOR TELEVISION WHEN BOTH WANTED AND UNWANTED SIGNALS ARE SUBSTANTIALLY NON-FADING

(1970)

In planning networks of television transmitters it has so far been assumed, at least for bands I and III, that interference from an unwanted co-channel television transmission will occur for only a small proportion (say up to 1 0 %) of the time, because it has been possible to ensure adequate geographical separation between wanted and unwanted transmitters.

In spite of the use of high-power transmitters using high-gain aerials situated in elevated positions, it has been found necessary, particularly in the UHF bands, to supply a relatively large number of low-power (say less than 10 kW e.r.p.) relay stations, not only in the region just outside the service area of a main (high-power) station, but also within the nominal service area. In this way the smaller areas that may have high population density may also be adequately served. A network of main and relay stations such as can be envisaged from the above descrip tion will need to use the same channel many times, due to the restricted number of channels available. The same channel will reappear in many different locations and several Such loca tions may be geographically quite close together.

This Report considers the protection ratio required for a wanted emission that suffers interference from a single unwanted emission, at a receiving site which is relatively close to the latter. In this case, the interference will be almost continuous and the protection ratios given in Recommendation 418-2, based as they are upon interference that is present for only a small proportion of the time (say up to 1 0 %), will, it is thought, be unacceptable. This Report assumes that there must be a relationship between the percentage of time for which interference is present and the criterion of impairment that should be used when planning a television broadcasting service. Thus, if the criterion of impairment be taken as “ definitely perceptible but not disturbing” for interference present for about 1 0 % of the time, then the criterion for interference that is present for almost all the time might well be taken as “just perceptible” . It is assumed that an increment of 10 dB added to the protection ratios given in Recommendation 418-2 would change the criterion from the “ definitely perceptible but not disturbing” value to the “just perceptible” value. Evidence in favour of the figure of 10 dB arises from two sources. The first may be found in the first paragraph of the Intro duction to the Annex to Recommendation 418-2. The second source of information was an analysis of results from co-channel interference tests that were conducted by the B.B.C. in 1962.

When planning co-channel emissions that will suffer from almost continuous inter ference it is essential to bear in mind that it is the median level of the (almost non-fading) interfering signal that the wanted (non-fading) signal level should exceed by an adequate margin. That is, the interfering signal and the wanted signal must be taken from the appro priate C.C.I.R. propagation curve for 50% of the time (Recommendation 370-1) rather than from the curves for 1 0 % or 1 % of the time. We thus have possible rules to aid in planning. One procedure should be adopted for long-distance interference and the other for short-distance cases where fading scarcely occurs, that is, where the “fading range” of the interfering signal is less than, say, 10 dB. For these

* This Report was adopted unanimously. Rep. 479 — 126 —

purposes, the fading range may be defined as the difference in decibels between the field strength exceeded for 1 % of the time and that exceeded for 50 % of the time (the median value of the field strength)*. Use of the fading range as the criterion to adopt in deciding whether the interference is long-distance or short-distance is more precise than choosing a geograph ical distance that would take no account of the irregularity of the terrain intervening between the interfering transmitter and the service area of the wanted transmitter. Further more, the fading range takes account of the height of the antenna of the interfering transmitter. The procedures may be summarized as follows: — if the fading range is equal to or greater than 10 dB, the interference is “long-distance” and the appropriate protection ratio taken from Recommendation 418-2 must be added to the field-strength curve (from Recommendation 370-1) appropriate to the desired percentage of time for which protection is required. Note that the fading range of the wanted signal may have to be taken into account; — if the fading range is less than 10 dB, the interference is “short-distance” and in this case it is suggested that 10 dB be added to the value of the protection ratio obtained from Recommendation 418-2 and the sum of these two quantities be then added to the median value curve for 50% of the time (from Recommendation 370-1) of the field strength curve of the interfering emission. In addition to the non-fading signals considered in this Report, there are conditions in which the wanted signal fades and the interfering signal does not fade. Moreover, in some conditions both signals fade. A general procedure for planning, taking into account the presence or absence of time-fading of both signals and also of their variation in field strength from location to location, is given in Report 485.

* The fading range is, of course, directly related to the standard deviation of the statistical distribution curve expressing field strength as a function of percentage of time. — 127 — Rep. 480

REPORT 480 *

PROTECTION RATIOS FOR NON-PRECISION OFFSETS BETWEEN TELEVISION SIGNALS THAT ARE MULTIPLES OF ONE-TWELFTH LINE-FREQUENCY (Question 4-1/11) (1970) 1. Introduction . The information given in this Report is supplementary to the technical data that were available to the European VHF/UHF Broadcasting Conference, Stockholm, 1961. Although the information given below is directly applicable to all 625-line monochrome television systems it is believed that it is also valid for all 625-line colour television systems.

2. Protection ratios for offsets that are multiples of one-twelfth line-frequency The Table gives figures based on the assumption of transmitter stabilities of ±500 Hz. The figures are valid at multiples of one-twelfth line-frequency up to about 50 kHz.

Offset (multiples of 1/12 line-frequency) 0 l 2 3 4 5 6 7 8 9 10 11 12

Protection ratio (dB) 45 44 40 34 30 28 27 28 30 34 40 44 45

Administrations concerned are invited to undertake further studies of the figures given in the Table in their television networks.

* This Report was adopted unanimously. Rep. 482 — 128 —

REPORT 482 *

RECOMMENDED CHARACTERISTICS FOR COLLECTIVE AND INDIVIDUAL ANTENNA SYSTEMS FOR DOMESTIC RECEPTION OF SIGNALS FROM TERRESTRIAL TRANSMITTERS (Question 7-1/11) (1970) 1. Scope Installations may be classified according to the number of users served. An individual antenna serves one user, even though it may be associated with several receivers. A collective antenna serves all or part of a building and hence a larger number of users. This Report applies to antenna systems for individual and collective use designed to receive television broadcasts in bands 8 (VHF) and 9 (UHF) and also to the associated equipment of such systems; the transmission line, amplifiers, couplers, etc. used to convey the signal to the television receivers. It does not apply to television antennae for wired distribution systems.

2. Frequency range

The parts of bands 8 (VHF) and 9 (UHF) allocated to broadcasting and used for television.

3. Amplitude/frequency characteristic The amplitude/frequency characteristic of the system, excluding the antenna, should be uniform within 3 dB for each channel at each individual outlet.

4. Nominal output impedance In unbalanced systems, the nominal impedance should be 75 Q. In balanced systems, the nominal impedance should be 300 fl.

5. Noise figure (see Recommendation 331-2, § 2) in particular when the system includes active elements:

— lower part of band 8 (VHF) ^ 9 dB — upper part of band 8 (VHF) % 9 dB — lower part of band 9 (UHF) % 12 dB — upper part of band 9 (UHF) < 15 dB unless the peak-to-peak picture signal-to-r.m.s. unweighted noise ratio at the video signal output of the receiver is greater than 37 dB.

6. Reflection coefficient Band 8 Band 9 Passive equipment <0-25 <0-33 Couplers and filters <0-33 < 0-33 Active equipment < 0-33 <0-33

* This Report was adopted unanimously. — 129 — Rep. 482

7. Interference

7.1 The installation should cause neither interference at fixed frequencies nor cross-modulation products (between signals from different transmitters) which, assuming they are referred to the receiver input, would interfere (in the sense of Recommendation 418-2 or Report 306-1) with reception from the wanted transmitters, in the service area as defined by the protected field. 7.2 An echo, whether it originates outside or inside the installation will not be considered as inter fering if the wanted signal/echo ratio is greater than or equal to 20 dB. The case of multiple echoes remains to be studied. 7.3 The installation, in particular the devices for preventing interference or echoes, e.g.: — high-gain antennae with a front-back ratio of not less than 18 dB, — multiple antennae, — echo correctors, should not cause, in the channels of the transmissions normally received discernible defects such as smear, hum, loss of synchronization, interference patterns, or interference in general.

8. Signal level at each outlet The following are the limits within which the signal to be applied to the television receiver should lie, measured at the terminals of the appropriate resistance: Maximum Minimum (dBm) — lower part of band 8 (VHF) — 2 0 — 51 upper part of band 8 (VHF) — 2 0 — 51 — lower part of band 9 (UHF) — 3 0 — 48 — upper part of band 9 (UHF) — 3 0 — 48

9. Colour television The system, including the antenna, should be capable of receiving broadcasts in colour made according to the C.C.I.R. system in use by the transmissions to be received. In particular, the amplitude of the sub-carrier should not differ from its nominal value by more than ± 2 dB. This value refers to the system excluding the antenna (see § 3 ). Particular care must be taken regarding intermodulation products between vision, sound-and colour-carrier frequencies falling into the useful radio-frequency band.

10. Oscillators and other equipment used in the system The levels of the energy radiated and of the energy reinjected into the distribution system should be less than the values which may be specified by the C.I.S.P.R. The total frequency drift of the oscillators should not exceed the value of ± 75 kHz for variations in the supply voltage of ± 10% and a temperature range of — 10° C to + 55° C* This value applies to both band 8 (VHF) and band 9 (UHF).

11. Isolation between outlets The isolation between two different outlets must be at least 22 dB for all the frequencies in the broadcasting bands. This value assumes that the frequency allocation and the inter mediate frequency of the receivers have been planned to avoid interference.

* Further information is requested. Rep. 482 — 130 —

Note. — This value is raised to 46 dB between an outlet for television signals in bands 8 and 9 and an outlet for frequency modulation sound broadcasting signals with two different users. The selection circuits required form an integral part of the installation.

12. Antenna characteristics The gain shall be expressed relative to that of a half-wave dipole for each of the channels to be received. Subject to further studies, the directivity characteristics of the antenna should meet the provisions of Recommendation 419. The antenna gain should be uniform within ± 2 dB throughout the bandwidth of each of the channels which are indicated as being receivable by the antenna. The impedance should be matched to the nominal impedance of the system used (see § 4). Protection against a linearly polarized wave, whose polarization plane is perpendicular to that of the antenna, should be greater than 20 dB. This limit only applies to reception in the main lobe of the antenna.

Bibliography

1. C.C.I.R. Doc. XI/6 (United Kingdom), 1966-1969. 2. C.C.I.R. Doc. XI/25 (France), 1966-1969. 3. C.C.I.R. Doc. XI/49 (Canada), 1966-1969. 4. C.C.I.R. Doc. X I/165 (France), 1966-1969. 5. C.C.I.R. Doc. XI/169 (Spain), 1966-1969. 6. C.C.I.R. Doc. XI/184 (Italy), 1966-1969.

\ — 131 — Rep. 483

REPORT 483 *

SPECIFICATIONS FOR LOW-COST TELEVISION RECEIVERS

(Question 13/11) (1970) This Report is a reply to Question 13/11. It presents values for the characteristics of low-cost television receivers suitable for home and community use. Values are based on information in the following documents: Docs. XI/53 (Italy), 1966-1969, XI/132 (United Kingdom), 1966-1969, XI/164 (France), 1966-1969, XI/185 (Italy), 1966-1969 and XI/192 (India), 1966-1969.

1. General 1.1 Types o f receiver These specifications apply to two types of low-cost monochrome television receiver giving a satisfactory performance: Type A: Receivers intended to give acceptable performance at the lowest possible cost. Type B: Receivers intended to give good performance at a reasonable cost. Generally speaking Type A receivers would be home receivers whereas Type B receivers would often be community receivers. It should be noted that in establishing the performance specifications listed below due consideration was given to the situation prevailing in many developing countries where the normal utilities have not reached the required level. As a result of this the requirements of certain parameters of a television receiver are severe and this adds to the cost.

1.2 Power supply Where feasible, the use of a.c. mains operated receivers is recommended. In some countries, battery-operated receivers are at present either of lower performance, or of higher cost. The Administrations concerned should specify the television standard to be employed and the mains voltage and frequency, if the receivers are to be mains-operated. Particular emphasis should be given to any difference that may exist between the mains frequency and the field frequency of the television system, whether due to intentional differences or to temporary disturbances. For battery-operated receivers, satisfactory performance should be secured with the battery voltage 2 0 % below the nominal value.

1.3 Controls The following controls, at least, should be available to the user: — power switch, — channel selector and tuning, — contrast, — brightness, — sound volume.

* This Report, which was adopted unanimously, has been brought to the notice of Study Group 1. Rep. 483 — 132 —

1.4 Planning o f uses In planning the uses of these receivers, Administrations should take account of their differing characteristics, the range of signal intensity expected, and the possibilities for special antennae, pre-amplifiers and low-loss radio-frequency feeders. Although it is desirable that receivers should be capable of operation on all channels, receivers equipped to receive only the channels of the transmitters serving the given area and conforming to the frequency plan may be acceptable. Administrations should further take account of the effect of the size of the screen and the cabinet on cost. The recommended values given are considered appropriate for the expected use of the receivers. The receivers should be simple, robust and well protected against the environment. Those intended for use in areas of high temperature, high humidity or dust should be treated so that they can be used under the climatic conditions specified by the Administration concerned. Appropriate tests, consistent with the relevant IEC Publications*, should be prepared by the Administration concerned. 1.5 Safety The receiver should comply with the safety recommendations of IEC Publication 65.

1.6 Methods of measurement The methods of measurement and the tests to be employed should be those recommended in relevant paragraphs of IEC Publications 106 (1959), 106A (1962) and 107 (1960). National regulations or tests differing from these standards should be quoted.

1.7 Receiver tuning For all the measurements which follow, the receiver should be accurately tuned as described in IEC Publication 107-1, § 4.8.2 or, if this is not appropriate, in some other specified manner.

2. General specifications Type A Type B 2.1 Recommended size (diagonal) for the screen 28 cm 48 cm (1 1 in.) (19 in.) or larger or larger 2.2 Frequency bands VHF VHF or or VHF and VHF and UHF UHF (see § 1.4 above, second sub-paragraph) 2.3 Power supply for a.c. operation Frequency: — nominal value (Hz) To be specified by the Administration concerned — maximum variation (Hz) ± 5 ±5 Voltage: — nominal value (V) To be specified by the Administration concerned

* The IEC Publications quoted in the text are the most up-to-date issues at the time of preparation of the Report. — 133 — Rep. 483

Type A Type B maximum permissible variation without extra equip ment (%) ± 1 0 ± 1 0 freedom from damage for surges of ... * ms duration and changes of (%) ± 30 ± 30 Note. — It will be up to the user to provide a means of voltage control for variations greater than ± 1 0 %.

3. Input characteristics 3.1 Input impedance at the antenna terminals (C2) 75 and/or 300 75 and/or 300 3.2 Maximum noise figure (dB) (least favourable channel) Band 8 — VHF 1 0 8 Band 9 — UHF 16 1 2 3.3 Noise-limited sensitivity at a signal-to-noise ratio o f 30 dB and standard output (IEC 107, § 3.3) (dBm) Band 8 — VHF - 50 - 60 Band 9 — UHF - 4 0 - 55 3.4 Characteristic o f the automatic gain control (IEC 107, §§ 3.6/3.7) ( - 20 to - 50 dBm) (dB) 8 6

4. Output characteristics 4.1 Minimum audio-frequency passband within 6 dB (IEC 107, § 12.3) (Hz) 150-5000 150-5000 4.2 Minimum audio-frequency output at 10% distortion (IEC 107, § 13.2.5) (W) 0-5 2 4.3 Minimum picture resolution ** (IEC 107, § 2.6) (lines per picture height) — 6 MHz channel systems (4-5 MHz intercarrier frequency) 225 280 — 7 or 8 MHz channel systems (5-5, 6 or 6-5 MHz inter carrier frequency) 270 a 320 4.4 Minimum brightness at white level for a black level o f 3 cd/m2 (IEC 107, § 2.4.1) — 50 fields/s system (cd/m2) 70 1 2 0 — 60 fields/s system (cd/m2) 70 150 4.5 Minimum interlace ratio (IEC 107, § 2.9) 30/70 30/70 4.6 Maximum picture motion expressed as a percentage o f picture height for a difference o f 1 Hz between the mains frequency and the field frequency (IEC 107, § 2.3.1.1) (%) 0 - 8 0-4 4.7 Maximum relative non-linearity o f scan over a complete field (IEC 107, § 2.3.2) (%) 1 0 6 4.8 Maximum distortion o f the picture outline (IEC 107, §2.3.3) (%) 1 0 6

* The value is under study. ** Alternatively, Administrations may wish to specify their requirements on resolution in terms of an electrical bandwidth measurement (e.g. according to IEC 107, § 5.2) in which case the requirement must be negotiated with the manufacturer. Rep. 483 — 134 —

5. Interference 5.1 Intermediate frequency The picture and sound intermediate frequencies used in the receivers should be in accordance with those chosen for the establishment of the given frequency plan. * For standard K\, see, for instance, Doc. 44 of the African Broadcasting Conference, Geneva, 1963.

Type A Type B 5.2 Minimum rejection o f the upper adjacent picture carrier (IEC 107, § 4.2) (dB) 26 32 5.3 Minimum rejection o f the lower adjacent sound carrier (IEC 107, § 4.2) (dB) 30 35 5.4 Minimum image rejection (IEC 107, §4.5) Band 8 — VHF (dB) 40 40 Band 9 — UHF (dB) 20 25 5.5 Minimum intermediate-frequency rejection (IEC 107, §4.4) Band I — VHF (dB) 20 20 Band III — VHF, bands IV, V — UHF (dB) 30 30 5.6 Minimum crosstalk (IEC 107, § 4.8.1) Vision into sound (dB) 30 30 Sound into vision (dB) 40 40 5.7 Minimum attenuation o f the sound carrier relative to the vision carrier at the video detector (dB) 30 34 Note. — This requirement is to avoid beats in the receiver between the sound carrier and a subsequent colour sub-carrier. 5.8 Radiation (IEC 106j 106A ) In accordance with Recommendation No. 24/2 of the C.I.S.P.R. Note. — Unless otherwise specified by the Administration concerned, no measurements will be made below 0-5 MHz (LF Broadcasting).

6. Stability

Type A Type B 6.1 Maximum drift o f the local oscillator between 2 min and 60 min after the picture appears (IEC 107, § 6.1.3) VHF (kHz) ± 300 ± 300 UHF (kHz) ± 500 ± 500 6.2 Drift o f the local oscillator due to a change o f ± 10°(0 in the supply voltage (IEC 107, § 6.1.6) (kHz) ±100 ± 100 6.3 Minimum range o f lock-in (IEC 107, § 6.2.3)

Vertical \ (0/, 1 . Horizontal / (A) ± ±

* For economic reasons the number of different intermediate frequencies should be kept to a minimum (see Report 184-1). — 135 — Rep. 483, 484

6.4 Minimum range o f hold (IEC 107, § 6.2.3) Type A Type B Vertical Horizontal (%) ±2 ±2

7. Reliability The precise specification of reliability for a complete equipment is a subject under general study at the present time but manufacturers of receivers of the type considered in this Report should utilize as far as it is possible components already reliability tested under appropriate conditions. Since it is expected that these receivers will be closely based on ones already in quantity production, data on the reliability performance of such receivers should be available under normal operating conditions. The following figures are only provisional objectives suggested for receiver manufac turers and should on no account be considered as part of any contract. Type A Type B Desirable minimum mean operating time between failures requiring servicing, averaged over a production run (hours) 1 0 0 0 2 0 0 0

REPORT 484 *

RATIO OF PICTURE-SIGNAL TO SYNCHRONIZING-SIGNAL

(Question 1/11, Study Programme ID/11) (1970) Study Programme ID/11 considers the possibility of adopting one single figure for expressing the ratio of picture-signal to synchronizing-signal, for both the video and the radiated signals, independently of the systems employed. It is considered desirable that such a ratio should reach as high a value as possible, compatible with receiver requirements. It is felt that, to reduce the relative amplitude of the synchronizing signal below the values normally used, might give rise to difficulties in receivers and some types of studio equipment. Also, at the present time, the possible values of picture-signal to synchronizing-signal ratios that can be considered for a single standard are as follows: 7/3 and 10/4. Since the ratio 10/4 is the higher of the two and is more generally used for radiated signals (some countries using it also for the video signal), Administrations should consider the pos sibility of adopting this value in the future.

Bibliography

1. C.C.I.R. Doc. XI/15 (CMTT) (Italy), 1966-1969. 2. C.C.I.R. Doc. CMTT/81 (Rev. 3), 1966-1969. 3. C.C.I.R. Doc. XI/151 (Italy), 1966-1969.

* This Report was adopted unanimously. Rep. 485 — 136 —

REPORT 485 *

CONTRIBUTION TO THE PLANNING OF BROADCASTING SERVICES Statistics of service (Question 4-1/11) (1970)

1. The protection ratio is frequently used in the planning and assignment of broadcast stations and service, both visual and aural. It is usually defined as the minimum permissible power ratio of the wanted-to-interfering signals available at the receiver input, to provide the desired quality grade of service. Because the field strengths which induce the receiver input signals vary with time and from location to location, it is necessary to include some of the statistics of this variability in the description of service and for the protection of this service. The television or frequency-modulation broadcasting service to a relatively small area in the presence of a single source of interference may be described by an algebraic-statistical equation (1). A small area is one for which changes in the type of terrain and in the distance from the pertinent transmitting antennae are negligible in terms of determining the median values of field strength. R{Q) = Fd (50,50) - Fu (50,50) + Ga - Gu - H(T) - H(L) ' (1)

where H(T) = k{T) ] / c + a V td tu

H(L) = k(L) l / a 2 + c v id lu

R(Q) : protection ratio (dB) of the wanted to the interfering signal at the receiver input required to provide a service quality Q under non-varying conditions. Subscripts d and u refer to the wanted and unwanted signals, respectively; F(L', T') : the level of field strength exceeded for T'% of the time in at least L'% of the locations (dB rel. 1 fjtV/m); F(50,50) : median field strength in time and location (dB rel. 1 p.V/m); G : effective receiving antenna gain in the pertinent direction (dB); k(X ) : standard normal variate, tabulated in many statistical textbooks: *(50) = 0; *(70) = - 0 525; *(90) = - 1-282; *(99) = - 2-326; at : standard deviation for variation in field strength with time (dB); ci : standard deviation for variation in field strength from location to location (dB). For the purpose of describing service, equation (1) may be interpreted as follows. If service of quality grade Q is defined to be available at a given location only when the protec tion ratio at the receiver input exceeds the required value R (Q), i.e. the non-varying protec tion ratio is exceeded for T% of the time, then in the area for which equation (1) holds, at least L % of the locations will have this quality of service, Q. H (T) and H(L) are the factors

* This Report was adopted unanimously. — 137 — Rep. 485 which represent the effects upon the service to the area of the signal variability in time and with location, respectively.

In equation (1) the following assumptions have been made:

— the various fields have approximately Gaussian distributions both in time and with loca tion. Experience [1] indicates that this is a fair approximation between the 5 % and 95 % levels; — both the time correlation and location correlation between the desired and interfering signals are negligible. Terms including these correlation terms may be added to the radicals of H(T) and H(L), if desired; — the variability in antenna gain throughout the small area is assumed to be negligible. Terms for the variability in antenna gain may be added to the radical of H(L) but such terms should be minor for outdoor installations compared with the location variability of the field strength. It is noted from equation (1) that there are three interdependent parameters needed to describe the service to the area—i.e. Q, L, T. For convenience, Q and T are usually stan dardized and with these standard values of T and Q a value of L may be computed from (1). For example, Q may be chosen as “satisfactory” service and T as 90% or 99%. When several sources, i, of interference, including noise, are present at the area, the for each source of interference acting independently and alone may be computed from equation (1 ), and the resultant L may be computed as the product of the values of Lt so long as the values of Q and T are the same for the individual computations of Li [1].

L = 1 n Li = Lx L2 . . . . Ln (2) ;=l

The above resultant value of L is a reasonably good approximation for values of L equal to 50% or greater.

Equation (1) may be rearranged to give: R(Q) + H{T) + H(L) = Fd(50,50) - FM(50,50) + Gd - Gu (3)

The right-hand side of equation (3) is recognized as being equal to the ratio of the median value of the wanted-to-interfering signal powers at the receiver input. When the signals are of the non-varying type, H(T) and H(L) are zero and the ratio of the median values of the receiver input powers is equal to the ratio R(Q). But, when there is time and location varia bility (and T or L exceeds 50 %) a greater ratio of median receiver input powers is required for the same quality of service Q, the increase being represented by H(T) and H(L) for time and location variability in signal strength, respectively. In effect, a statistical, multi-dimensional protection ratio may be created to represent the left-hand side of equation (3). For allocation and assignment computations R(Q) may be combined with H{L) and sometimes H(T) to create a new multi-dimensional power input statistical ratio which is more easily used with available propagation data. These ratios have often been confused with the non-varying protection ratios. When possible H(T) should be combined with the median values of field strength to avoid the creation of a statistical protection ratio which varies with distance. For protection of service areas iso-service contours of equal location probability L (Q and T being preset) are drawn to depict the coverage of the broadcasting station and these iso-service contours are protected. Standard values for L need to be adopted by the C.C.I.R. in addition to presently recognized standards for T and Q, to set protection standards for iso service contours under conditions of signals variable in time and with location. Rep. 485 — 138 —

2. Co-channel television interference For this type of protection, H(L) is combined with R(Q), and H(T) is merged with FM(50,50). Thus, under the assumption that the time fading ranges of the interfering fields are at least twice as great as those for the wanted fields:

R(L,Q) = R(Q) + H(L) Fd(50,50) - FM(50,100-F) + Gd - Gu (4) FM(50,50) + H (T) & FM(50,100-F) R(L,Q) is convenient for use in computations to protect the service of the wanted station, especially since it is not dependent upon distance. However, R(L,Q) may be frequency dependent, since H(L) is frequency dependent, as shown in Table I. This Table is given as an example only and for various types of terrain, the values of a may be higher or lower than those given.

3. Adjacent channel interference When the fading of the interfering signal is much smaller than that for the wanted signal, H(T) may be combined with Fd(50,50). Such would be the case for adjacent channel interference in System M, if the value of R(Q) = — 20 dB, as proposed in Doc. XI/35 (U.S.A.), 1966-1969, is adopted. For such conditions: R(L,Q) = R(Q) + H(L) Fd(50,T) - Fu{50,50) + Gd - Gu (5) F«*(50,50) - H(T) ^ Fd(50,T) When the time fading of the wanted and interfering signals are approximately the same, H(T) cannot be conveniently combined with one of the median field strength signals.H{T) is then assumed to have a typical value which is independent of distance, and is combined with R(Q) and H(L). R(L,T,Q) = R(Q) + H(L) + H (T) ^ Fd{50,50) - Fu (50,50) + Gd — Gu (6 )

4. Conclusions It is concluded that defining only the non-varying protection ratio for the broadcast services is not sufficient to define the quality of a service nor to define protection requirements for such service. It is also necessary to define the percentage of time T for which this ratio is to be exceeded as well as the percentage of locations L for which the desired quality of service Q is desired. Given this more completely specified statistical quality of service, available propagation and antenna pattern data may be employed to determine the ratio of wanted to interfering field strengths which may be needed to provide the required protection. From these field strengths the required service contours and station separation may be compiled.

T a b l e I Examples of values for H(L)

Frequency (MHz) 70 100 200 700

Old = alu = Ol (dB) 7 7 8 12

H( 50) (dB) 0 0 0 0

H(70) (dB) - 5 ' - 5 - 6 - 9

H(90) (dB) - 1 2 - 1 2 -15 - 2 2 #(99) (dB) -23 -23 -2 6 -3 9 — 139 — Rep. 485

Bibliography 1. Report of the ad hoc Committee for the evaluation of the radio propagation factors concerning the TV and FM broadcasting services in the frequency range between 50 and 250 Me. Vols. I and II —Available from Clearinghouse for Federal Scientific and Technical Information, National Bureau of Standards, U.S. Department of Commerce, Vol. IPB 166696, Vol. IIPB 166697. 2. C.C.I.R. Doc. XI/143 (U.S.A.), 1966-1969. PAGE INTENTIONALLY LEFT BLANK

PAGE LAISSEE EN BLANC INTENTIONNELLEMENT — 141 — Q. l/ll

QUESTIONS AND STUDY PROGRAMMES, RESOLUTIONS AND OPINIONS

(study group 11)

QUESTION 1/11

COLOUR TELEVISION STANDARDS

The C.C.I.R., (1955) CONSIDERING (a) that Question 64 does not cover all aspects of the problems arising in the standardization of colour television; (b) that, in Europe at least, the situation in bands I and III differs from that in bands IV and V, and that, in deciding on colour systems for bands I and III, individual Administrations may find it convenient to use systems compatible with their monochrome systems already working in these bands; (c) that, as bands IV and V have not yet been exploited in many countries, it is desirable and theoretically possible for these countries to achieve a common standard for these bands; (d) that, in choosing a colour system for bands IV and V, Administrations may well be influenced by any colour systems which they may have adopted for bands I and III, and that this possibility complicates the choice of common standards; decides that the following question should be studied: what standards can be recommended for colour television for public broadcasting? Account should be taken of such points as: — satisfactory picture (colour and monochrome) and sound quality; — economical use of bandwidth; — reliable receivers of reasonable cost; — operation of studio, transmitting and relaying equipment; — susceptibility to interference; — compatibilities (see Note); — frequency planning; — international exchange of programmes; — scope for development; — the differences between bands I and III, as compared with bands IV and V.

Note. — A compatible colour television system is one that produces acceptable monochrome versions of the colour pictures on existing monochrome receivers. A reverse compatible colour television system is one that produces acceptable monochrome pictures on colour receivers from existing monochrome transmissions: in either case, bandwidths of the colour and monochrome systems may be the same or different. S.P. 1A/11, IB/11,1C/11 — 142 —

STUDY PROGRAMME 1A/11

STANDARDS FOR VIDEO COLOUR-TELEVISION SIGNALS

The C.C.I.R. (1965) unanimously decides that the following studies should be carried out:

1 . the preferred colorimetric parameters for representing the television picture;

2 . the gamma pre-correction; 3. the scanning standards that can be recommended, e.g. sequential (field, line, dot), simulta neous or mixed; 4. comparison of the various methods of coding and decoding the colour picture information; 5. the minimum acceptable bandwidths for the signal components, corresponding to these parameters.

STUDY PROGRAMME IB/11

STANDARDS FOR RADIATED COLOUR-TELEVISION SIGNALS

The C.C.I.R. (1955) decides that the following studies should be carried out: comparison of different colour television systems, in terms of the criteria listed in the text of Question 1/11. This comparison should pay particular attention to colour television systems which are either in operation, or which are, or have been, the subject of experiment.

STUDY PROGRAMME 1C/11

CONSTITUTION OF A SYSTEM OF STEREOSCOPIC TELEVISION

The C.C.I.R., (1958) CONSIDERING (a) the possible future development of stereoscopic television broadcasting; (b) the great utility this form of television may have;

decides that the following studies should be carried out:

1. Stereoscopic monochrome television

1 .1 investigation into the development of methods of providing stereoscopic television, not requiring the use of spectacles; — 143 — S.P. 1C/11, ID/11

1 .2 study of the possibility of decreasing the bandwidth of stereoscopic television broadcasting, e.g., by transmitting one picture of the stereoscopic couple with the full standardized band width and the other with a reduced bandwidth on a sub-carrier within the first frequency spectrum; 1.3 study of the influence of noise on stereoscopic television pictures and determination of the permissible signal-to-noise ratio; 1.4 investigation of the design of receivers with direct reproduction of stereoscopic pictures, e.g., by taking the structure of receiving-tube displays as a basis for the lay-out of the phospho rescent elements;

2. Stereoscopic colour television

2 .1 the carrying out of tests, to assess the quality of colour reproduction with binocular mixing of its components, in respect of the stability of picture detail (“field-clash”);

2 . 2 study of the possibility of decreasing the frequency band for stereoscopic colour television, e.g., by transmitting the green field of the stereoscopic couple with the full standardized band, the red and blue fields being transmitted by means of a sub-carrier within the first frequency spectrum; 2.3 research into the design of receivers for the direct reproduction of stereoscopic colour tele vision.

STUDY PROGRAMME ID/11

RATIO OF PICTURE-SIGNAL TO SYNCHRONIZING-SIGNAL

The C.C.I.R., (1970) CONSIDERING (a) that it is desirable that both the video and radiated signals should have the same ratio of picture-signal to synchronizing-signal;

(b) that it is also desirable that all television systems should employ the same ratio of picture- signal to synchronizing-signal;

(c) that modern television receivers might be able to function with a higher ratio of picture- signal to synchronizing-signal than at present used, thus improving transmitter performance;

unanimously decides that the following studies should be carried out:

determination of a single value for the ratio of picture-signal to synchronizing-signal which could be recommended in the future for both the video and radiated signals of all television systems. S.P. IE/11,1F/I1 — 144 —

STUDY PROGRAMME IE/11

SIMPLIFICATION OF SYNCHRONIZING SIGNALS IN TELEVISION

The C.C.I.R. (1970) unanimously decides that the following studies should be carried out: the effect of a reduction of the number of equalizing pulses upon: — the quality of field synchronization in monitoring equipment and in domestic receivers; — the quality of interlacing in monitoring equipment and in domestic receivers; — the vulnerability of domestic receivers to interference, especially when the frequency of the interfering signal has a precise offset from that of the wanted signal; — the sensitivity of domestic receivers with respect to synchronization; — the reliability of synchronization of domestic receivers when operating with an asyn chronous power supply; — the special problems that may arise in video tape recording as a result of modifications to the synchronizing signal.

STUDY PROGRAMME IF/11 *

ALLOCATION OF TOLERANCES FOR COLOUR TELEVISION

The C.C.I.R., ‘ (1970) CONSIDERING (a) that the subjective quality of colour television pictures is affected by the objective performance of every component part of an overall television system from picture source up to and includ ing the receiver; V (b) that the relationship between objective parameters of television signals and subjective assessments of displayed picture quality is under study (Study Programme 14A/11); unanimously decides that the following studies should be carried out: allocation of the specified total tolerances among the component parts of an overall television system from picture source up to and including the receiver, taking into account the statistical behaviour of departures from the nominal performance figures of the equipment.

* This Study Programme is to be studied jointly with the CMTT. — 145 — Q. 2-1/11, S.P. 2-1 A/ll

QUESTION 2-1/11

EXCHANGE OF TELEVISION PROGRAMMES

The C.C.I.R., (1966 - 1970) CONSIDERING (a) that it is desirable to exchange television programmes between countries; (b) that a variety of television standards is in use; (c) that the number of scanning standards used throughout the world tends to be reduced to two, namely the 525 lines, 60 fields per second standard and the 625 lines, 50 fields per second, the line frequencies of which are very near; unanimously decides that the following question should be studied: which methods can be used to enable television programmes to be exchanged between coun tries in the following cases:

1 . when the nominal field frequencies are the same, but the numbers of lines are different, or vice versa;

2 . when both the nominal field frequencies and the numbers of lines are different; 3. when the nominal field frequencies are the same and the numbers of lines are the same, but the synchronizing signals are different in form; 4. when the nominal line and field frequencies are the same but the colour television systems are different?

Note. — Programme exchanges: — between different monochrome systems, — between different colour systems, — and between monochrome and colour systems should be considered.

STUDY PROGRAMME 2-1 A /ll

TRANSCODING OF COLOUR TELEVISION SIGNALS FROM ONE SYSTEM TO ANOTHER

The C.C.I.R. (1970) unanimously decides that the following studies should be carried out:

1 . methods of transcoding from one colour television system to another having the same nominal line and field frequencies;

2 . tolerances required of a colour television signal to ease the problem of transcoding it into another system. Q. 3-1/11, S.P. 3-1A/11 — 146 —

QUESTION 3-1/11

ASSESSMENT OF THE QUALITY OF TELEVISION PICTURES

The C.C.I.R., (1951 - 1956 - 1970

CONSIDERING (a) that appreciable discrepancies may exist between assessments by different experts of the quality of the pictures given by the television systems now in use or proposed; (b) that these discrepancies are due to the fact that it is usually impossible to obtain simultaneous viewing of the pictures under comparison, to possible variations in quality between apparatus nominally using the same system and to alterations that may occur with time in the charac teristics of the equipment used; (c) that, consequently, it would be eminently desirable to have some standard method of meas uring television picture quality, which would permit objective comparison of the results obtained in different places and would serve as a guide to the efficient and uniform working of the equipment in service; (d) that the quality of television pictures is determined by the transmission parameters of equip ment which can be measured objectively and which can be related to the subjective picture quality;

unanim ously decides that the following question should be studied:

1 . what standardized methods and means of test, independent of the television standards employed, can be used to measure accurately, and whenever possible, objectively, the deterior ation introduced into monochrome and colour pictures by television, taking into account the system, the equipment and the transmission processes;

2 . what are the relationships between the objective parameters of television signals and the subjective assessments of displayed picture quality ? 1

STUDY PROGRAMME 3-1 A /ll

SUBJECTIVE ASSESSMENT OF THE QUALITY OF TELEVISION PICTURES

The C.C.I.R., (1963 - 1966)

CONSIDERING (a) that subjective methods of testing are frequently necessary to assess the relative quality of television pictures and the effect of interference and other impairments upon them; (b) that many different methods of subjective testing are possible; (c) that the results of subjective tests depend on the conditions under which they are carried out; (d) that the results of subjective tests can be interpreted in many ways; (e) that it is highly desirable to standardize the methods of subjective testing and the interpreta tion of the results, so that true comparisons may be made between results obtained at different times; — 147 — S.P. 3-1 A/ll, Q. 4-1/11

unanimously decides that the following studies should be carried out:

1 . on the methods of subjective testing best suited to the assessment of the relative quality of television pictures and of the effects of interference and other impairments upon them, taking particular account of: — the use of full-range opinion-rating methods and the scales to be used and, alternatively, the use of comparison methods of assessment; — the selection of test pictures; — the viewing conditions; — the selection and number of observers; — the instructions to observers before tests;

2 . on the analysis and presentation of the results obtained; 3. on the use of the methods described in §§ 1 and 2 during international transmissions.

QUESTION 4-1/11

RATIO OF THE WANTED-TO-UNWANTED SIGNAL IN TELEVISION

The C.C.I.R., (1955 - 1963 - 1970) CONSIDERING that the satisfactory operation of a television service renders it necessary to specify the maximum field strength of interfering or unwanted signals which can be tolerated, without unduly affecting the reception of television programmes; unanimously decides that the following question should be studied:

1 . determination of the protection ratio, when two or more television transmitters are operating: — in the same channel, — in adjacent channels, — with dissimilar but partially overlapping bandwidths;

2 . determination of the protection ratios against services, other than television, in the shared bands ?

Note 1. — The reply to the Question should give the protection ratios required when all the trans mitters are radiating monochrome signals on the one hand, or colour signals on the other hand, and when the wanted transmitter is radiating monochrome signals and the others are radiating colour signals and vice versa; and it should take into account all the different signal standards that may be used and should also indicate percentage of time during which protection is desired. Separate answers may be required for various grades of service. Note 2. — See Recommendation 418-2 for monochrome television and Report 306-1 for colour television. Note 3. — See Report 307 for protection against radionavigation transmitters. S.P. 4-1 A/ll, Q. 5-1/11 — 148 —

STUDY PROGRAMME 4-1 A/ll

RATIO OF THE WANTED-TO-UNWANTED SIGNAL IN TELEVISION Use of the offset method, when there are great differences between the carrier frequencies of the interfering stations The C.C.I.R., - (1959 - 1963) CONSIDERING (a) that, when there is partial overlapping of the channels occupied by a wanted and an unwanted signal, offset operation makes it possible to reduce the protection ratios for monochrome television and thus facilitate the planning of television networks over territories where different television standards are used (see Recommendation 418-2); (b) that a similar advantage may possibly be obtained for colour television; unanimously decides that the following studies should be carried out: an investigation of the extent to which offset working can be used in colour television, when there are large differences between the carrier frequencies of the wanted and unwanted signals. Note. — See Report 306-1 for information on protection ratios for colour television, when the carrier frequency differences between wanted and unwanted signals are small.

QUESTION 5-1/11 *

BROADCASTING SATELLITE SERVICE Television

The C.C.I.R., (1965 - 1966 - 1970) CONSIDERING (a) Recommendation No. 5A of the Extraordinary Administrative Radio Conference, Geneva, 1963; (b) that television broadcasting from satellites may soon become possible because of technical progress; (c) that the technical consequences of television broadcasting from satellites must be taken into account, including the possible sharing of frequency bands between television broadcasting satellites and the terrestrial broadcasting service as well as other terrestrial services; (d) that the use of television broadcasting satellites could cause difficulty in the sharing of fre quencies by television broadcasting satellites and between other space services, and will also affect the utilization of the geostationary orbit; unanimously decides that the following question should be studied:

1 . what are the optimum transmission characteristics for single and multiple television broad casting from satellites taking into account both transmission and reception equipment;

* Contributions to the study of this Question should be brought to the attention of participants in the work of Study Groups 4 and 10, and to Study Group 9 for contributions on §§ 4 and 5. — 149 — Q. 5-1/11, S.P. 5-1A/11

2 . what are the frequency bands which are technically suitable for television broadcasting from satellites; 3. what are the possibilities for sharing frequency bands between television broadcasting satellites and the terrestrial broadcasting services; 4. what are the possibilities for sharing frequency bands between television broadcasting satellites and other terrestrial services, particularly in bands 9 and 10; 5. what are the values of field strength necessary to provide a satisfactory television broadcasting satellite service and to protect terrestrial services if sharing is envisaged;

6 . what are the possibilities of sharing frequency bands between television satellites taking into account the efficient utilization of the geostationary orbit; 7. what are the possibilities of sharing frequency bands between television satellites and other space services taking into account the efficient utilization of the geostationary orbit;

8 . what other aspects of planning, designing and operating systems using television satellites influence the choice of the principal characteristics of such systems, taking into account expected technical developments?

STUDY PROGRAMME 5-1 A/ll

WORLD-WIDE STANDARD FOR TELEVISION BROADCASTING FROM SATELLITES

The C.C.I.R., (1966) CONSIDERING (a) that the line-of-sight propagation from satellites presents the possibilities of exploiting bands not at present used for television broadcasting; (b) that, with the use of a new band, a new transmission standard may be desirable; (c) that use of the wide coverage possibilities of television broadcasting from artificial satellites is simplest if a single standard is used within the coverage area; unanimously decides that the following studies should be carried out:

1 . determination of the frequency bands technically suitable for this service;

2 . determination of the values of the parameters controlling picture and sound quality (resolu tion, permissible contrast range and brightness, etc.) and, if different from existing standards, the reason for the differences; 3. establishment of a basic transmission system, including the method of modulation which could provide high-quality monochrome and colour reception, and also acceptable mono chrome reception with low-cost receivers; 4. the possibility of transmitting the colour information within the video spectrum of the luminance signal; 5. the number of sound channels which could be provided and the manner in which they could be transmitted. S.P. 5-1B/I1, 5-1C/I1 — 150 —

STUDY PROGRAMME 5-1B/11

COMPOSITE 625-LINE SIGNAL FOR TELEVISION BROADCASTING FROM SATELLITES

The C.C.I.R., (1966)

CONSIDERING

(a) that television broadcasting from satellites is inherently a wide area service; (b) that transmitting on existing television standards on bands currently used may be a method of instituting such a service; (c) that there are numerous variations between existing standards, especially in the 625-line systems;

unanimously decides that the following studies should be carried out:

1 . the possibility that satisfactory results can be obtained on receivers built to existing standards, without change, or with a minimum number of changes, when receiving a composite 625-line transmission, composed of one vision signal plus two, three or more sound signals;

2 . the possibility of accomplishing any necessary changes by adapters (introduced, for example, between the picture tube and its connecting socket); 3. the increases in receiver complexity that would be incurred if dual standard receivers were to be developed for reception of an existing standard and the composite signal.

STUDY PROGRAMME 5-1C/11

POSSIBLE BROADCASTING-SATELLITE SYSTEMS FOR TELEVISION AND THEIR RELATIVE ACCEPTABILITY

The C.C.I.R., (1970)

• CONSIDERING

(a) that it is technically possible at present to establish a terrestrial television broadcasting service with distribution of programmes by earth stations participating in the communication-satellite service; (b) that studies of the technical characteristics of a television broadcasting-satellite system are now being undertaken; (c) that, to supplement these technical characteristics, the cost of such systems (covering both the capital cost and the running cost) should be taken into account; (d) that these factors may influence the choice of systems; (e) that comparative cost is not the absolute deciding factor but an extra consideration to be borne in mind; — 151 — S.P. 5-1C/11, 5-1D/11

unanimously decides that the following studies should be carried out:

1 . comparison of the different television broadcasting-satellite systems for either individual or community reception, taking the technical aspects and capital and running costs into account;

2 . evaluation of the feasibility and possible uses of each system in the light of the technical and economic factors involved. Note. — These studies will be carried out, taking into account the more detailed economic studies made by the Technical Cooperation Department of the I.T.U. and in conjunction with that Department.

STUDY PROGRAMME 5-ID/11

BROADCASTING SATELLITE SERVICE (TELEVISION) FOR COMMUNITY RECEPTION

The C.C.I.R., (1970) CONSIDERING (a) the possibility of community reception as defined in Report 471; (b) that new or developing countries are especially interested in the study of community reception; (c) that operating conditions and reception quality for community reception of signals from broadcasting satellites are expected to be appreciably different from the conditions and reception quality for individual reception; (d) that this difference in operating conditions and reception quality may well enable a satis factory television broadcasting satellite service to be established at an early date, and at a reasonable cost; unanimously decides that the following studies should be carried out:

1 . the optimum characteristics of a broadcasting satellite for television for community reception to provide economical coverage of areas of the Earth which are not generally served by tele vision transmitters;

2 . the frequency bands which would be technically appropriate; 3. ■ the modulation standards and video frequency characteristics which would ensure optimum service at lowest cost; 4. the possibilities of coexistence with other broadcasting services; 5. the number of possible television sound channels and methods of transmission to be adopted. S.P. 5-1E/11, 5-1F/11 — 152 —

STUDY PROGRAMME 5-1E/11

BROADCASTING SATELLITE SERVICE (TELEVISION) Types of modulation for bands 9 and 10

The C.C.I.R., (1970) CONSIDERING (a) that it may be desirable to utilize bands 9 and 10 for television transmission in the broad casting satellite service; (b) that the present amplitude-modulation vestigial-sideband emission requires an excessively high satellite transmitter power in bands 9 and 10 to produce the primary grade of reception quality; unanimously decides that the following studies should be carried out:

1 . satisfactory alternative forms of modulation, other than amplitude modulation for television transmission in the broadcasting satellite service in bands 9 and 10;

2 . the preferred standards for transmission and conditions for reception.

STUDY PROGRAMME 5-1F/11

CHARACTERISTICS OF A TELEVISION RECEIVING SYSTEM FOR DIRECT TRANSMISSIONS FROM SATELLITES

The C.C.I.R., (1970) CONSIDERING (a) that an Administrative Radio Conference will be held in 1971 to consider the allocation of frequencies in the bands 8 (VHF), 9 (UHF) and 10 (SHF) for satellite broadcasting; (b) that technology will have developed sufficiently to make the use of broadcasting satellites practicable in the mid-1970’s (see Report 473); (c) that the choice of frequency bands to be used and the transmission standards are of great importance for the following characteristics of the receiving equipment: — engineering design, — cost, — reliability, — ease of control; (d) that, particularly for community reception * which would probably be the first to be achieved, the frequency-modulation system for television would allow a lower radiated power from the satellite; (e) that the characteristics of the receiving equipment are of considerable importance in deter mining the total system cost; (f) that the frequency bands and standards chosen must not produce a serious interference problem between satellite and terrestrial transmissions;

* Community reception is defined in Report 471. — 153 — S.P. 5-1F/11, Q. 6/11, S.P 6A/11

unanimously decides that the following studies should be carried out:

1 . determination of the characteristics of receiving equipment, enumerated in § (c), for the reception of frequency-modulation television systems taking particular account of the require ments for community reception and the fact that the cost of the equipment will depend both on the specification and the number of receiving equipments required;

2 . determination of the characteristics of receiving equipment for an amplitude-modulation satellite system in accordance with one of the existing television standards, it being borne in mind that the basic characteristics of Report 482 may be applicable but with additional data appropriate to the particular frequency bands used.

Note. — The studies undertaken in connection with Study Programmes 5-1B/11, 5-1C/11, 5-1D/11 and 5-1E/11 should be taken into account in pursuing the studies of §§ 1 and 2.

QUESTION 6/11

GHOST IMAGES IN TELEVISION

The C.C.I.R., (1966) CONSIDERING (a) that it is often necessary to locate a television transmitting antenna in the vicinity of other antenna structures; (b) that this can result in undesirable ghost images in the received picture; unanimously decides that the following question should be studied:

1 . what factors must be considered to ensure satisfactory ghost-free operation;

2 . how can these factors be evaluated?

STUDY PROGRAMME 6A/11

GHOST IMAGES IN TELEVISION

The C.C.I.R. (1966) unanimously decides that the following studies should be carried out:

1 . the ratio of direct-to-delayed reflected signal required for satisfactory television service, taking into account: — polarity of the ghost images; — displacement of ghost images from wanted images;

2 . the methods of calculation to be used to determine the ratio and displacement of the direct and reflected signals which result from antenna structures in the vicinity of television radiators, taking into account factors such as radiation, polarization, etc. Q. 7-1/11, S.P. 9A/11 — 154 —

QUESTION 7-1/11

RECOMMENDED CHARACTERISTICS FOR INDIVIDUAL OR COLLECTIVE TELEVISION ANTENNA SYSTEMS FOR DOMESTIC RECEPTION OF SIGNALS FROM TERRESTRIAL TRANSMITTERS

The C.C.I.R., (1965 - 1970) CONSIDERING (a) that the antenna and its associated components are important elements of the transmission chain; (b) that their characteristics have an influence on the performance of receivers; unanimously decides that the following question should be studied: what characteristics should be recommended for individual or collective domestic television antennae and associated equipment?

STUDY PROGRAMME 9A/11*

DISTORTION OF TELEVISION SIGNALS DUE TO THE USE OF A VESTIGIAL-SIDEBAND EMISSION

The C.C.I.R., (1956) CONSIDERING (a) that vestigial-sideband emission of television signals is an accepted practice in broadcasting; (b) that this class of emission results in overall distortion, which is a combination of: — quadrature distortion inherent in the method, — distortion caused by non-uniformity of group-delay in transmitter circuits, — distortion caused by non-uniformity of group-delay in receiver circuits; (c) that the importance of the individual contributions listed in § (b), in respect of the overall degradation of the received picture, has not been established; unanimously decides that the following studies should be carried out:

1 . the quantitative assessment of the respective distortion introduced in a television system using vestigial-sideband emission, due to : — quadrature error, — group-delay error at the transmitter, — group-delay error at the receiver;

2 . suitable methods to be adopted for measuring and correcting such distortions; 3. the extent to which such corrections should be introduced at the transmitter.

* This Study Programme does not arise from any Question at present under study. — 155 — S.P. 10A/11, 11A/11

STUDY PROGRAMME 10A/11 *

CONVERSION OF A TELEVISION SIGNAL FROM ONE STANDARD TO ANOTHER The C.C.I.R. (1951) unanimously decides that the following studies should be carried out: methods of converting a television signal from one standard to another: — when the field frequency is identical in the two standards, but the number of lines differ; — when both the field frequency and the number of lines are different in the two standards.

STUDY PROGRAMME 11 A /ll *

REDUCTION OF THE CHANNEL CAPACITY REQUIRED FOR A TELEVISION SIGNAL The C.C.I.R., (1958) CONSIDERING (a) that the large channel capacity required for the transmission of television signals introduces problems which are both technical and economic; (b) that the need for large channel capacity limits severely the maximum distance over which television signals can be transmitted by radio; (c) that all present-day methods of transmitting and receiving television signals are wasteful, in that they require a channel capacity greatly exceeding that which is necessary to transmit the essential information contained in a television picture; (d) that it is superfluous to transmit more information than can be recognized by the human eye; decides that the following studies should be carried out:

1 . the methods which can be used to reduce the required channel capacity for a television signal without reducing perceptibly the quality of the reproduced picture;

2 . the way in which removal of redundancy (signal compression) can best be exploited to reduce the bandwidth required for transmission; 3. the possibility of transmitting a signal from point to point, by converting it into another (intermediate) signal which has been processed to have a bandwidth smaller than that of the original signal in keeping with a reduction of channel capacity; 4. the best method of exploiting signal compression to increase the range over which television signals can be transmitted, taking into account that, for a fixed rate of information, it is in general possible to exchange bandwidth and signal-to-noise ratio; 5. the ways in which knowledge of the characteristics of the human eye can be used, to reduce to a minimum the amount of information which it is required to transmit to reproduce a satisfactory television picture.

* This Study Programme does not arise from any Question at present under study. S.P. 12A/11, Q. 13/11 — 156 —

STUDY PROGRAMME 12A/11 *

INSERTION OF SPECIAL SIGNALS IN THE FIELD-BLANKING INTERVAL OF A TELEVISION SIGNAL

The C.C.I.R., (1962 - 1963 - 1966) CONSIDERING (a) that it is already current practice in a number of countries to insert special signals in the field- blanking interval of a television signal; (b) that such signals can be used for checking the performance of the circuits over which the television signal is transmitted; (c) that such signals might be used for supervision or various control purposes and for the transmission of information on the operation of international networks;

unanim ously decides that the following studies should be carried out:

1 . whether special signals can be inserted in, and removed from, the field-blanking interval of the television signal, without detriment to the quality of the television picture itself;

2 . the purposes for which such signals should be used internationally; 3. the points at which these signals should be inserted in the international television connection and, possibly, removed again; 4. the provisions to be made to avoid confusion between signals for national and international use; 5. the forms of special signal to be recommended for international use; 6 . the position in the field-blanking interval of signals for measuring the characteristics of television networks; 7. the position in the field-blanking interval of signals associated with control functions and the transmission of operational information;

8 . the best system of encoding for the signals referred to in § 7.

QUESTION 13/11 **

SPECIFICATIONS FOR LOW-COST TELEVISION RECEIVERS

The C.C.I.R., (1968) CONSIDERING (a) Resolution 163 (VIII) adopted by the Economic Commission for Africa at its Eighth Session, Lagos, 13-25 February 1967;

* This Study Programme does not arise from any Question at present under study. It is identical to Study Programme 1-1C/CMTT. ** This Question also concerns Study Group 1, the Chairman of which should be kept informed of the results obtained by Study Group 11 as they become available. — 157 — Q. 13/11, 14/11, S.P. 14A/11

(b) that the advantages of television should be made more easily available to the populations of the countries where at present the density of receivers is particularly low for economic, geographic or technical reasons;

(c) that, to this end, it is desirable that efficient television receivers should be available at prices low enough to secure their wide distribution in these countries;

(d) that general agreement on the performance of suitable television receivers would prove most useful to radio receiver manufacturers by assisting them to produce suitable receivers having an agreed adequate standard performance at the lowest possible cost;

decides that the following question should be studied:

to draw up performance specifications for one or more types of television receiver, suitable for production in large quantities at the lowest possible cost, the receivers to meet the requirements applying to the countries mentioned in § (b).

QUESTION 14/11

SUBJECTIVE QUALITY TARGETS OF OVERALL TELEVISION SYSTEMS

The C.C.I.R., (1970) CONSIDERING (a) that, in some parts of the world, television transmission circuits much longer than 2500 km and including satellite links, either exist or are under construction; (b) that, with the advent of communication satellites, new types of television service are possible; (c) that the evaluation and planning of systems to provide these services requires a knowledge of desirable subjective quality targets;

unanim ously decides that the following question should be studied: what are the desirable subjective quality targets of an overall television system, from picture source to receiver, for the various types of service?

STUDY PROGRAMME 14A/11

SUBJECTIVE QUALITY TARGETS OF OVERALL TELEVISION SYSTEMS *

The C.C.I.R., (1970) CONSIDERING (a) that the performance of a television service is determined by the performance of all the component equipment used in providing it; S.P. 14A/11, Q. 15/11 — 158 —

(b) that existing methods of the assessment of the quality of television pictures are contained in Report 405-1; (c) that Study Programme 2-1A/CMTT, § 2, is concerned with a determination of the objective performance of reference chains consistent with desirable overall subjective quality;

unanimously decides that the following studies should be carried out:

1 . the quality targets that must be specified in the design of the various kinds of television services planned or in existence, both monochrome and colour;

2 . the values to be assigned to the necessary design targets; 3. the relationships between objective parameters of television signals and subjective assessments of displayed picture quality; 4. the laws of addition of subjective effects when several causes of picture impairment are present simultaneously.

QUESTION 15/11

AUTOMATIC MONITORING OF TELEVISION STATIONS *

The C.C.I.R., (1970) CONSIDERING (a) that the number of television broadcasting and relaying stations is constantly growing; (b) that the increasing demands on television stations (especially in connection with the intro duction of colour television) call for higher accuracy and objectivity in monitoring; (c) that the considerations in §§ (a) and (b) above impose exacting requirements for monitoring and measuring equipment and on the qualifications of servicing staff, with the result that the operation of television stations is becoming more costly; (d) that the introduction of fully automated television stations necessitates the automation of monitoring and the automatic maintenance of quality parameters; (e) that Administrations are interested in the greatest possible unification of methods and equipment used in monitoring and measurement at transmitting stations and in the video and sound channels of long distance international links;

unanimously decides that the following question should be studied:

1 . what characteristics and quality parameters of television stations must be monitored automa tically during transmission;

2 . what are the most effective methods of automatic monitoring; 3. what signals are best suited to automatic monitoring; 4. how should the automatic monitoring system be organized;

* This Question, which is intended to cover both picture and the associated sound transmitter, has been brought to the notice of Study Group 10. — 159 — Q. 15/11, 16/11

5. what are the basic requirements regarding equipment and the methods used for automatic monitoring; 6. what are the effects of automatic monitoring during transmission upon the extent to which routine measurements are required and the equipment required for them; 7. to what extent is it possible to unify the methods and devices for monitoring television sta tions with the methods and devices used in other sections of a television chain;

8. what are the most efficient ways of using monitoring results for the automatic maintenance of quality parameters and to ensure the satisfactory operational control of the station?

QUESTION 16/11 *

STANDARDS FOR THE INTERNATIONAL EXCHANGE OF MONOCHROME TELEVISION PROGRAMMES Film recording and reproducing

The C.C.I.R., (1965 - 1966 - 1970)

CONSIDERING (a) that films used for the international exchange of television programmes do not always match the reproducing characteristics of the telecine equipment at the film’s destination; (b) that reproducing characteristics differ in various telecine equipment; (c) that a telecine characteristic should be defined for optimum reproduction of films intended for international exchange of television programmes; (d) that further specifications concerning optimal density values and transfer characteristics of photographic films for television are desirable; (e) that, to achieve comparable results, methods of density measurement should also be recom mended;

unanim ously decides that the following question should be studied:

1 . what are the optimum telecine reproducing characteristics for use with television films;

2 . to what extent can the various telecine reproducing characteristics be modified, to meet the optimum standard referred to in § 1 ; 3. if the modifications in § 2 are not practicable, what is the best compromise standard; 4. what methods of measurement and specification should be used for defining density range of photographic films used for television programme exchange; 5. what should be the tolerances on the transfer characteristics within the recommended density range of a film image, as defined in Recommendation 265-2, § 3.4?

* This Question replaces Question 5/X of former Study Group X and is identical with that text. Q. 17/11, 18/11 — 160 —

QUESTION 17/11 *

OPTICAL SOUND RECORDING AND REPRODUCING STANDARDS FOR THE INTERNATIONAL EXCHANGE OF TELEVISION PROGRAMMES

The C.C.I.R., (1966 - 1970) CONSIDERING (a) that, when films intended for the international exchange of television programmes have optical sound tracks, these sound tracks do not always reproduce satisfactorily in telecine equipment; (b) that, although international standards exist for the location and dimensions of optical sound tracks, there do not appear to be national or international standards for their recording and reproduction characteristics; (c) that compression of the sound signal is invariably used to obtain a satisfactory signal-to- noise ratio; (d) that the signals reproduced from optical sound tracks have noticeably different characteristics from those originating from other programme sources;

unanimously decides that the following question should be studied:

1 . what are the optimum optical sound recording characteristics for the two film gauges used for international programme exchange;

2 . what are the preferred methods of measurement of the recording and reproducing charac teristics; 3. what are the preferred types of optical sound track for international programme exchange; 4. what is the optimum compression characteristic consistent with satisfactory signal-to-noise ratio; 5. is it possible, by the use of volume expansion in telecine reproducing equipment, or by other means to reduce the difference between the sound quality obtained from optical tracks and that obtained from other programme sources ?

QUESTION 18/11 **

RECORDING OF TELEVISION SIGNALS ON MAGNETIC TAPE

The C.C.I.R., (1963 - 1970) CONSIDERING that various types of equipment are being developed for magnetic recording of monochrome and colour television signals;

* This Question replaces Question 6/X of former Study Group X and is identical with that text. ** This Question replaces Question 7/X of former Study Group X and is identical with that text. — 161 — Q. 18/11, S.P. 18A/11,18 B /ll

unanimously decides that the following question should be studied:

1. what are the methods of magnetic recording of television programmes which can be used by broadcasting organizations;

2. what standards should be established to enable the international exchange of such recordings to be made?

STUDY PROGRAMME 18A/11 *

RECORDING OF TELEVISION SIGNALS ON MAGNETIC TAPE

The C.C.I.R., (1965 - 1970) CONSIDERING (a) that there is at present a system of magnetic recording of television programmes used for the international exchange of programmes; (b) that a study should be made of possible improvements to both the mechanical and the elec tronic aspects of the system;

unanimously decides that the following studies should be carried out:

1 . standards for the geometric and kinematic characteristics of the machines, with a view to improved reliability in the exchange of programmes;

2 . the best methods of dealing with the video-frequency signal in relation to the overall quality of the system; 3. standards relating to the use of tracks for the recording of sound.

STUDY PROGRAMME 18B/11

STANDARDS FOR THE INTERNATIONAL EXCHANGE OF TELEVISION PROGRAMMES ON MAGNETIC TAPE Helical-scan recording

The C.C.I.R., (1970) CONSIDERING (a) that the quality of helical-scan magnetic recordings obtainable with some equipment may prove acceptable for the exchange of programmes; (b) that a variety of standards would be wasteful and impede the international exchange of pro grammes;

* This Study Programme replaces Study Programme 7A/X of former Study Group X. S.P. 18B/11, 18C/11, Q. 19/11 — 162 —

unanimously decides that the following studies should be carried out:

1. the minimum requirements necessary to specify the performance of magnetic helical-scan recorders, in order to define the standards for the international exchange of programmes;

2. the tape width, spool dimensions, and recording format.

STUDY PROGRAMME 18C/11

MEASURING METHODS FOR TELEVISION TAPE RECORDING

The C.C.I.R., (1970) CONSIDERING (a) that the interchangeability of recordings made on various television tape machines requires that strict tolerances should be applied to certain parameters; (b) that standardized measuring methods are necessary to ensure the reproduction of tapes, intended for international exchange, without impairment of overall quality; (c) that the measuring methods defined in existing publications are insufficient to check all essential characteristics of tapes and machines;

unanimously decides that the following studies should be carried out:

1 . the recording and reproducing characteristics which affect the quality and interchangeability of tape recordings;

2 . the methods of measuring these characteristics; 3. the characteristics of suitable measuring equipment.

QUESTION 19/11 *

MAGNETIC SOUND RECORDING AND REPRODUCING STANDARDS FOR THE INTERNATIONAL EXCHANGE OF TELEVISION PROGRAMMES ON FILM

Recording and reproducing characteristics for 16 SEPMAG and 16 COMMAG

The C.C.I.R., (1968 - 1970) CONSIDERING (a) that Recommendation 265-2 specifies that for 16 COMMAG the recording and reproducing characteristics should be that standardized by the C.C.I.R. for magnetic tape for a speed of 19-05 cm/s except for the time constant which is 100 [j.s (see Recommendation 408-2); (b) that this recommended standard has not been universally adopted;

* This Question replaces Question 21/X of former Study Group X and is identical with that text. — 163 — Q. 19/11, 20/11, 21/11

(c) that the present multiplicity of standards for magnetic sound on 16 mm film recording and reproduction creates difficulties within broadcasting organizations;

unanimously decides that the following question should be studied: should a compromise between the ISO and S.M.P.T.E. recording and reproducing charac teristics, such as the 70 {xs time constant specified in Recommendation 408-2, be adopted for both 16 COMMAG and 16 SEPMAG film?

QUESTION 20/11 *

RECORDING OF COLOUR TELEVISION SIGNALS ON FILM

The C.C.I.R., (1968 - 1970) CONSIDERING (a) that colour films are a medium for the international exchange of colour television programmes, as stated in Report 406, § 6 .8 ; (b) that direct filming of programmes is not always possible for technical and economic reasons; (c) that no simple, satisfactory system seems to be available in practice for recording colour television programmes on colour film;

unanimously decides that the following question should be studied:

1 . what system or systems are most satisfactory for producing colour films from a live colour television programme or from one recorded on magnetic tape;

2 . what are the optimum recording characteristics which would meet the standards that may be adopted for films intended for the international exchange of colour programmes ?

QUESTION 21/11 **

STANDARDS FOR THE INTERNATIONAL EXCHANGE OF COLOUR TELEVISION PROGRAMMES

Film recording and reproducing

The C.C.I.R., (1968 - 1970) CONSIDERING that it is desirable to define: (a) the colour balance for both 16-mm and 35-mm films; (b) the conditions of projection for the assessment of both 16-mm and 35-mm colour films;

* This Question replaces Question 22/X of former Study Group X and is identical with that text. ** This Question replaces Question 23/X of former Study Group X and is identical with that text. Q. 21/11, 22/11, S.P. 22A/11 — 164 —

unanimously decides that the following question should be studied:

1 . at which colour temperature should films intended for television and used for international programme exchanges be balanced;

2 . what are the optimum conditions of projection for assessment of colour films intended for tele vision; 3. what are the suitable maximum and minimum densities of colour films intended for television; 4. what are the optimum telecine reproducing characteristics for use with colour television films; 5. to what extent can the various telecine reproducing characteristics be modified, to meet the optimum standard referred to in § 4 ?

QUESTION 22/11 *

METHODS OF SYNCHRONIZING VARIOUS RECORDING AND REPRODUCING SYSTEMS

The C.C.I.R., (1968 - 1970) CONSIDERING (a) that Question 18-1/10 concerns the simultaneous transmission of two sound channels in television; (b) that present television tape recorders provide for only one sound channel of broadcast quality; (c) that in other cases, also, it may be necessary to synchronize a number of audio and/or video signals with each other; (d) that no single method or system is in general use which will meet all the different possible requirements for synchronization;

unanimously decides that the following question should be studied:

1 . what are the required capabilities of such methods of synchronizing;

2 . what methods are applicable to the synchronization of the various types of recording and reproducing devices?

STUDY PROGRAMME 22A/11

RECORDING OF CODED INFORMATION ON THE CUE TRACK OF TELEVISION MAGNETIC TAPES

The C.C.I.R., • (1970) CONSIDERING (a) that the use of coded signals recorded on the cue track of television tapes for various purposes, is increasing rapidly;

* This Question replaces Question 24/X of former Study Group X and is identical with that text. — 165 — S.P. 22A/11, Q. 23/11

(b) that such coded signals could also be useful in connection with the international exchange of television tape programmes; (c) that for the latter purpose a unique system of coded signals should be adopted;

unanimously decides that the following studies should be carried out:

1. the type of information required to be recorded on the cue track, for the international exchange of programmes;

2. the code to be used to record this information.

QUESTION 23/11 *

FEASIBILITY OF DIRECT SOUND AND TELEVISION BROADCASTING FROM SATELLITES

The C.C.I.R., (1966 - 1970) CONSIDERING (a) that there are many parts of the world with little or no broadcasting service; (b) that there is considerable interest in the possibility of broadcasting from satellites; (c) that, in view of the extensive use of existing broadcasting bands below 1 GHz in some regions, there is particular interest in the feasibility of using frequencies above 1 GHz;

unanimously decides that the following question should be studied:

1 . what are the satellite orbits most satisfactory for direct broadcasting to the general public from satellites;

2 . what accuracy of positioning or station keeping can be achieved; 3. what maximum primary power is likely to be available to operate a transmitter in a satellite, and what other factors associated with the space environment operate to limit the power that could be developed in the transmitter at the various frequencies that might be used, up to 12-7 GHz, or possibly higher frequencies; 4. what gain, directivity and stability of orientation are attainable for satellite transmitting antennae at various frequencies; 5. what is the probable working life of a satellite, bearing in mind that failure in accurate posi tioning or antenna orientation may end the useful life?

* This Question, which replaces Question 12/IV and which is identical with Question 34/10, should be studied in connection with Questions 20-1/10 and 5-1/11; contributions to the study of this Question should be brought to the attention of participants in the work of Study Group 10. Q. 24/11, Res. 38 — 166 —

QUESTION 24/11 *

STUDY OF A DOMESTIC OR REGIONAL COMMUNICATION-SATELLITE SYSTEM FOR TELECOMMUNICATIONS AND SOUND AND TELEVISION BROADCASTING

The Plan Committee for Asia and Oceania, (1970) CONSIDERING (a) that the costs of communication satellites and earth stations have greatly reduced during the past few years; (b) that the cost of leasing a large number of telephone and television channels from international communication satellite systems for domestic or regional use may be uneconomical; (c) that the economic aspects of coaxial cable and radio-relay systems are being studied by C.C.I.T.T./C.C.I.R. Special Autonomous Working Party 3 (GAS 3), but comparable studies have not been carried out by the I.T.U. for communication-satellite systems; (d) that a group of countries might share the cost on a regional basis;

r e q u e s t s the Director, C.C.I.R. to arrange for the study of the technical and economic aspects for a domestic and/or regional satellite system, which would provide good quality telecommunications, television, and sound broadcasting transmissions to meet the desired requirements. As far as possible the economic studies to be carried out should be in accordance with the methods indicated in the GAS 3 Manual.

RESOLUTION 38

POSSIBLE BROADCASTING-SATELLITE SYSTEMS AND THEIR RELATIVE ACCEPTABILITY (Study Programmes 20B/10 and 5-1C/11)

The C.C.I.R., (1970)

considering (a) that studies of the technical characteristics of broadcasting-satellite systems are now being undertaken;

* This Question, which is identical with Question 35/10, was put to the C.C.I.R. by the Meeting o f the Plan Committee for Asia and Oceania, Teheran, 1970. — 167 — Res. 38, 58

(b) that, to supplement these technical characteristics, the comparative costs of such systems (covering both capital investment in and the operation of the major subsystems) should be taken into account; (c) that these technical and economic factors may influence the choice of systems; (d) that the considerations are of particular importance and urgency for new or developing countries; (e) that studies undertaken by the C.C.I.R. on possible broadcasting-satellite systems and their relative acceptability should provide useful information to the Technical Cooperation Department of the I.T.U.; UNANIMOUSLY DECIDES 1. that an Interim Working Party be established to carry out the following studies:

1 .1 comparison of different broadcasting-satellite systems or subsystems intended for either individual or community reception, taking the technical aspects and relative capital and running costs into account;

1 .2 evaluation of the feasibility and possible uses of each system in the light of the technical and economic factors involved, taking into consideration especially the operational requirements of new or developing countries;

2. that the concerned countries are urged to make known to the Chairman of the Interim Working Party their particular requirements at the earliest date possible; 3. that the Interim Working Party should be composed of representatives appointed by the Administrations of Argentina, Australia, Brazil, Canada, Federal Republic of Germany, France, India, Italy, Japan, Malaysia, New Zealand, Pakistan, Sweden, the Union of Soviet Socialist Republics, United Kingdom and United States of America, together with the Chairmen and Vice-Chairmen of the Study Groups concerned; 4. that the Chairman of the Interim Working Party shall be a representative of the Adminis tration of India; 5. that the Interim Working Party shall conduct its work expeditiously and as far as possible by correspondence, and shall only hold such meetings as are deemed absolutely necessary for the execution of its work;

6 . that reports of the proceedings of the Interim Working Party will be available to the C.C.I.R. Preparatory Meeting for the World Administrative Radio Conference for Space Telecommu nications and a final report to the Director, C.C.I.R., for consideration at the next Plenary Assembly; 7. that this Resolution be brought to the attention of interested organizations in the United Nations.

RESOLUTION 58

ASSESSMENT OF THE QUALITY OF PICTURES IN TELEVISION SYSTEMS The C.C.I.R., (1970) CONSIDERING (a) that Question 3-1/11 and Study Programme 3-1 A /ll seek to determine what objective measure ments should be made of picture signal quality and the relationship between the objective measurements and the subjective assessments of displayed picture quality; Res. 58 — 168 —

(b) that Question 14/11 and Study Programme 14A/11 seek to determine the desirable subjective quality targets of an overall television system from picture source to receiver for various types of service; NOTING (c) that Report 405-1 suggests methods for subjective testing and provides some data relative to Study Programme 3-1 A/11; (d) that Report 313-2 provides useful references to studies already made on the assessment of the quality of television pictures; BELIEVING (e) that these Reports provide only partial answers to the Questions and Study Programmes cited above; (f) that it is necessary to determine desirable quality targets for various types of service and in particular for community viewing in new or developing countries; (g) that it is essential to find answers to these problems urgently for monochrome television pro grammes in the 525- and 625-line systems to enable new or developing countries to plan their national television services; UNANIMOUSLY DECIDES 1. that an Interim Working Party to be known as Interim Working Party 11-1, within the terms of reference of Study Group 11, should be set up with the following terms of reference: 1.1 to determine the methods of subjective testing of the quality of television pictures (Study Programme 3-1 A/ll) appropriate in the first place to the needs of community reception of monochrome pictures in the 525- and 625-line television systems;

1 .2 to suggest the quality targets that might be considered appropriate in the first place for com munity viewing and the corresponding objective parameters that should be achieved (Questions 3-1/11, 14/11 and Study Programme 14A/11), taking into account as far as possible any special characteristics of the signals from broadcasting satellites; 2. that the result of the work of the Interim Working Party should be presented directly for information to the Special Joint Meeting of Study Groups of the C.C.I.R. preparatory to the World Administrative Radio Conference for Space Telecommunications and subsequently to the following meeting of Study Group 11; 3. that the undermentioned Administrations will be represented in the Interim Working Party: Canada, United States of America, France, India, Italy, Japan, Federal Republic of Germany, Switzerland, United Kingdom and U.S.S.R.; 4. that the Chairman of this Interim Working Party should be nominated by the Administration of the United Kingdom; 5. that the work of the Interim Working Party should as far as possible be carried out by correspondence. — 169 — Op. 38, 39

OPINION 38 *

EXCHANGE OF MONOCHROME AND COLOUR TELEVISION PROGRAMMES VIA SATELLITES

The C.C.I.R., (1970) CONSIDERING (a) the importance of facilitating the exchange of television programmes via satellites; (b) that, if this exchange is to be made between countries using the same standard or the same system, any conversion or any transcoding at intermediate points could lower the quality of the signal; IS UNANIMOUSLY OF THE OPINION that the attention of Administrations and organizations responsible for the transmission of international television programmes should be drawn to the desirability

OPINION 39

CHARACTERISTICS OF TELEVISION ANTENNAE FOR DOMESTIC USE

The C.C.I.-R., (1970) CONSIDERING (a) that there may be divergencies of opinion as to whether the IEC or the C.C.I.R. is the more appropriate organization for the study of questions concerning television antennae for domestic reception; (b) that, while on the one hand, the determination of definitions and methods of measurement of the various parameters can, in this particular case, be left to the IEC, after examination by the C.C.I.R., on the other hand, the determination of the values for these parameter's and the tolerances to be applied to them should be left to the C.C.I.R.; (c) that it is desirable that no ambiguity should remain, thus avoiding useless duplication of effort and the existence of a multiplicity of standards and the tolerances to be applied to them; IS UNANIMOUSLY OF THE OPINION 1. that the C.C.I.R. should determine those parameters of television antennae for domestic reception which are important to its work;

* This Opinion has been brought to the attention of Study Groups 4, 9 and the CMTT. Op. 39, 40 — 170 —

2. that the Director, C.C.I.R. should: — maintain close liaison with the IEC with a view to obtaining from the IEC appropriate definitions and methods of measurement; — communicate to the IEC the most appropriate values for these parameters and take all necessary steps to avoid duplication of effort and the existence of a multiplicity of standards.

OPINION 40

SUBJECTIVE ASSESSMENT OF THE QUALITY OF TELEVISION PICTURES

The C.C.I.R., (1970) CONSIDERING (a) that it has already done considerable work on the subjective assessment of the quality of television pictures (see Report 405-1); (b) that the IEC is also making a similar study with special reference to receivers; (c) that it is important to develop analogous assessment procedures to obtain consistent results; IS UNANIMOUSLY OF THE OPINION that the Director, C.C.I.R., should remain in close contact with the IEC to keep it informed of the wishes of the C.C.I.R. and to obtain the results of the work of the IEC with a view to arriving at one or more common methods of assessing picture quality and preventing dupli cation of work. — 171 —

TRANSMISSION OF SOUND BROADCASTING AND TELEVISION SIGNALS OVER LONG DISTANCES

CMTT

Joint C.C.I.R./C.C.I.T.T. Study Group for Television and Sound Transmissions

Terms o f reference:

To study, in cooperation with the Study Groups of the C.C.I.R. and the C.C.I.T.T., the specifications to be satisfied by telecommunication systems for the transmission of sound and television broadcasting programmes over long distances.

Chairman: Y. A ngel (France)

Vice-Chairman: W. G. Simpson (United Kingdom)

INTRODUCTION BY THE CHAIRMAN, CMTT

1. The Joint C.C.I.R./C.C.I.T.T. Study Group for Television and Sound Transmissions (CMTT) is administered by the C.C.I.R. and functions in the same way as other C.C.I.R. Study Groups.

2. According to its terms of reference (reproduced above), the task of the CMTT is to study the specifications to be satisfied by systems for the transmission of broadcasting signals (sound and television) over long distances. These studies apply to all systems of telecommunication, whether using guided propagation (e.g. coaxial cables) or free propagation (line-of-sight o r, trans-horizon radio-relay systems, space systems using satellites, etc.).

3. Concerning telecommunication by free propagation, the CMTT is called upon to exchange information with, in particular, C.C.I.R. Study Groups 2 and 4 (space systems) and 9 (radio relay systems).

4. As regards guided propagation of signals, in particular sound broadcasting, the CMTT has to exchange information with C.C.I.T.T. Study Groups IV, XII and XV and Special Joint Study Groups C and D.

5. Being concerned with sound and vision signals, the CMTT cannot ignore: — standards for the signals themselves, — the standardization of acceptable tolerances on noise and distortion, both for transmissions over a hypothetical reference circuit (or chain) and over real connections.

C.C.I.R. Study Groups 10 and 11 are responsible, in sound broadcasting and television respectively, for defining the overall qualities desirable in the transmission chain between the source of the programme and the domestic receiver. As the circuits with which the CMTT is concerned are an important link in this chain, the CMTT is called upon to cooperate actively with the two C.C.I.R. Study Groups in question. — 172 —

6 . An important point in the task of the CMTT is the study of methods of measurement and the test signals which may be recommended to monitor circuit characteristics. The CMTT has given its attention to this question in cooperation with C.C.I.R. Study Group 11 over several study periods and has drawn up two Recommendations and one Report. This study still continues, taking into consideration both specialized signal components for measuring different characteristics and the arrangement o f these components to make up test signals, in particular the insertion signals transmitted in each field-blanking interval.

7. An aspect of measurement, monitoring and maintenance of increasing importance at present is the automatic execution of these operations in television chains without interrupting the programme—the first stage towards the general use of information processing in network management. The CMTT has already drafted a Report on this problem and it is now speci fically set as a new Question with two related Study Programmes.

8 . Time-division multiplex systems make it possible to use a channel originally designed to carry the video component of a television programme for the simultaneous transmission of sound signals accompanying the picture. The CMTT also concerns itself with this type of problem.

9. With regard to sound programme transmissions, the CMTT has made a Recommendation and a number of Reports giving preliminary answers to the questions set on high-quality monophonic and stereophonic circuits, type A circuits, the emitted signals, compandors, noise from the power supply, etc. With a view to pursuing the study of circuit specifications, the C.C.I.R. has stated, in Opinion 41, that the function of the CMTT is to draw up overall performance specifications for programme circuits of various nominal bandwidths, but should not decide the bandwidths to be chosen for such specifications or on their classification, except for circuits of the highest quality.

10. The activity of the CMTT is divided into four sections: CMTT A : Standards for television transmission, CMTT B : Measurement, monitoring and maintenance, CMTT C : Joint transmission of sound and vision signals, CMTT D : Sound programme transmission. The same sub-division has been adopted in this Volume for classifying the Recommendations and Reports. — 173 — Rec. 421-2

SECTION CMTT A: TELEVISION TRANSMISSION STANDARDS

RECOMMENDATIONS AND REPORTS Recommendations

RECOMMENDATION 421-2

REQUIREMENTS FOR THE TRANSMISSION OF TELEVISION SIGNALS OVER LONG DISTANCES (SYSTEM I EXCEPTED)

The C.C.I.R., (1959-1963-1966-1970) CONSIDERING the agreement reached by the Joint C.C.I.R./C.C.I.T.T. Study Group for Television and Sound Transmissions (CMTT), on a draft Recommendation concerning television trans missions over long distances, common to the C.C.I.R. and the C.C.I.T.T.; UNANIMOUSLY RECOMMENDS

that, taking account of the definitions in § 1 , television transmissions over long distances should satisfy the requirements laid down in §§ 2 and 3 and their Annexes.

1. Definitions

Long-distance international Local line television circuit Local line

International television connection

Figure 1

1.1 Definition o f a long-distance international television connection (see Fig. 1) 1.1.1 Point A, to be considered as the sending end of the international television connection, may be the point at which the programme originates (studio or outside location), a switching centre or the location of a standards converter. 1.1.2 Point D, to be considered as the receiving end of the international television connection, may be a programme mixing or recording centre, a broadcasting station, a switching centre or the location of a standards converter. 1.1.3 The local line AB connects point A to the sending terminal station, point B, of the international television circuit. 1.1.4 The long-distance international television circuit, BC, comprises a chain of national and international television links. The precise locations (e.g. within buildings), to be regarded as the points B and C, will be nominated by the authorities concerned. Rec. 421-2 — 174 —

1.1.5 The local line CD connects point C, the receiving terminal station of the long-distance international television circuit, to the point D. 1.1.6 The combination AD, of the long-distance international television circuit, BC, and the local lines AB and CD, constitutes the international television connection. The requirements given in §§ 2 and 3 refer to the performance of long-distance inter national television circuits only; no requirements have been laid down for the local lines, AB and CD.

1.2 Definition o f the hypothetical reference circuit

The main features of the television hypothetical reference circuit, which is an example of a long-distance international television circuit (BC in Fig. 1) and which may be of either radio or coaxial-cable type, are:

— the overall length between video terminal points is 2500 km (about 1600 miles), — two intermediate video points divide the circuit into three sections of equal length, — the three sections are lined up individually and then interconnected without any form of overall adjustment or correction, — the circuit does not contain a standards converter or a synchronizing-pulse regenerator.

Note 1. — The concept of the hypothetical reference circuit serves to provide a basis for the planning and design of transmission systems. Such a circuit has a length which is reasonably but not excessively long and, for a television circuit, a defined number of video-to-video sections. It is appreciated that, at the present time, international television circuits usually contain more than three video-to-video links in a length of 2500 km, but it is expected that the number will be reduced in the course of time. Annex IV gives a provisional indication of the character istics of circuits with more or fewer video sections than the hypothetical reference circuit.

Note 2. — In Canada and the United States of America, objectives are normally specified for circuits 6400 km long. The limits given in this Recommendation for 2500-km circuits for the 525-line system in Canada and the United States of America are therefore chosen to give an adequate performance in a 2500-km portion of a 6400-km circuit.

2. Requirements at video interconnection points

In this section the requirements apply at the video terminals of any long-distance television circuit, whatever its length.

2.1 Impedance

At video interconnection points, the input and output impedance of each circuit should be unbalanced to earth, with a nominal value of 75 Q resistive and a return loss of at least 24 dB relative to 75 Q. The return loss, relative to 75 fl, of an impedance Z is

75 + Z 2 0 logx (dB). 75 - Z

Note 1. — In Canada and the United States of America, the impedance at video interconnection points should be either 124 Q balanced to earth or 75 D unbalanced to earth, with a return loss of at least 30 dB. Note 2. — In some countries, impedance is specified in terms of “waveform return loss” (see Doc. CMTT/9 (O.I.R.T.), 1963-1966 and Recommendation 451-1). — 175 — Rec. 421-2

2.2 Polarity and d.c. component At video interconnection points, the polarity of the signal should be positive, i.e. such that black-to-white transitions are positive-going. The useful d.c. component, which is related to the average luminance of the picture, may or may not be contained in the video signal and need not be transmitted, or delivered at the output. Any non-useful d.c. component unrelated to the video signal (e.g. the component due to d.c. valve supplies) should not cause more than 0-5 W to be dissipated in the 75 Q load impedance. If the load impedance is disconnected, the voltage of this component should not exceed 60 V.

2.3 Signal amplitude At video interconnection points, the blanking level taken as the reference level, the nominal amplitude of the picture signal, measured from the blanking level to the white level should be 0-7 V (0-714 V in Canada and the United States of America), while the nominal amplitude of the synchronizing signal, measured from the blanking level to the tips of the synchronizing pulses should be 0-3 V (0-286 in Canada and the United States of America), so that the nominal peak-to-peak amplitude of the video signal should be 1-0 V (see Fig. 2). Video signal

Picture signal

Synchronizing signal

Figure 2 V: Difference in potential between the terminal (not at earth potential) of the input (or output) impedance and earth (difference of potential positive in an upward direction).

Theoretically, the amplitude should be measured with the useful d.c. component of the video signal restored, but in practice this is not necessary. Note 1. — In the design of equipment, account should be taken of the losses in interconnecting cables when the video interconnection points are at some distance from the terminals of the modulating and demodulating equipment. Note 2. — For colour in system M (Japan), the above specification applies to the luminance and synchronizing signals. For the chfominance signal, further study is required.

3. Transmission performance of the hypothetical reference circuit In this section, the performance requirements are to be taken as design objectives applying to the hypothetical reference circuit as defined in § 1 .2 . Rec. 421-2 — 176 —

It should be emphasized that the material of this section constitutes only a first step towards the solution of the general problem of determining methods of measuring and specifying the performance of television circuits of any length or degree of complexity.

3.1 Insertion gain A long-distance international circuit, having the form of the hypothetical reference circuit should, at the time of setting up, have an insertion gain of 0 dB ± 1 dB (± 0-5 dB in Canada and the United States of America). The insertion gain should be measured, using Test Signal No. 2 (described in Annex I) and is defined as the ratio, in decibels, of the amplitude of the bar (from black level to white level) at the output to the nominal amplitude of the bar at the input. The measurement should be made under the following conditions: a generator producing Test Signal No. 2, with an internal impedance of 75 C2 (resistive)* is adjusted so that, if connected directly to a 75 resistance, it would produce a line- synchronizing signal of 0-3 V combined with a picture signal of 0-7 V which may include 0-05 V of pedestal. At the receiving end, the voltage between the black level and the white level (bar amplitude) is measured, using an oscilloscope connected across a resistance of 75 U. The ratio of this voltage to 0-65 V if pedestal is used, or 0-7 V if it is not (in decibels), is the insertion gain of the television circuit. Note. — In Canada and the United States of America somewhat different methods are used, but similar results are obtained.

3.2 Variations o f insertion gain The variations of insertion gain with time in the hypothetical reference circuit should not exceed the following limits: — short-period (e.g. 1 s) variations: ±0-3 dB (± 0 - 2 dB in Canada and the United States of America), — medium-period (e.g. 1 hr) variations: ± 1 0 dB. 3.3 Noise 3.3.1 Continuous random noise The signal-to-weighted noise ratio for continuous random noise is defined as the ratio, in decibels, of the peak-to-peak amplitude of the picture signal (see Fig. 2) to the r.m.s.* amplitude of the noise, within the range between 10 kHz and the nominal

T a b l e I

M System M (Japan) B, C, D, K, (See Report 308-2) (Canada monochrome G, H L F E and U.S.A.) and colour

Number of lines 525 525 625 625 819 819

Nominal upper limit of video-frequency band f c (MHz) 4 4 5 6 5 10

Signal-to-weighted noise ratio X (dB) 56 52 52 57 52 50

* Administrations measuring the quasi-peak-to-peak amplitude of the noise are asked to establish the crest factor appropriate to their method of measurement and to express the results in terms of r.m.s. amplitude. — 177 — Rec. 421-2

upper limit of the video frequency band of the system, f c. The purpose of the lower frequency limit is to enable power supply hum and microphonic noise to be excluded from practical measurements. For the hypothetical reference circuit, the signal-to-noise ratio should not be less than the values X given in Table I when measured with the appropriate low- pass filter, described in Annex II, the appropriate weighting network described in Annex III, and an instrument having an “effective time constant” or “integrating time” in terms of power of 1 s (0-4 s in Canada and the United States of America).

Note 1. — To obtain satisfactory transmission performance, television specialists believe that the signal-to-weighted noise ratio should fall neither below X (dB) for more than 1 % of any month, nor below X — 8 dB for more than 0-1 % of any month. Note 2. — For the routine measurement of signal-to-noise ratio on real circuits, the noise can be measured with sufficient accuracy in the absence of the video signal. The error introduced by this method will not, in general, exceed 2 dB. More accurate devices and methods for measur ing signal-to-weighted noise ratio when transmitting test signals, are described in Docs. XI/25, Moscow, 1958, CMTT/23, Monte Carlo, 1958, and CMTT/3, Paris, 1962, presented by the U.S.S.R.

T a b l e II

. M System (Canada M B, C, D, K, F E and (Japan) G, H L U.S.A.)

Number of lines 525 525 625 625 819 819

Nominal upper limit of video frequency band f c (MHz) 4 4 5 6 5 10

Signal-to-noise ratio (dB) for power-supply hum (including the fundamental frequency and lower-order harmonics) (x) 35 30 30 30 30 30

Signal-to-noise ratio (dB) for single-frequency noise between 1 kHz and 1 MHz 59 0 50 50 50 50 50 0

Value (dB) to which the signal-to-noise ratio for single-frequency noise may decrease linearly between 1 MHz and f c 43 0 30 0 30 30 30 30 0

(*) These figures apply only to hum added to the signal and not to hum which in transmission has modulated the amplitude of the signal and cannot be removed by clamping. The measurement should be made without clamping. (2) This limit applies between 1 kHz and 2 MHz. (3) For system E for frequencies below 1 kHz excluding power-supply hum (including both the fundamental frequency and lower-order harmonics), the signal-to-noise ratio may decrease linearly between the values 50 dB at 1 kHz and 45 dB at 100 Hz and between the values 45 dB at 100 Hz and 30 dB at 50 Hz. (4) Value to which the signal-to-noise ratio may decrease, according to a linear function on a chart having a linear decibel scale and a logarithmic frequency scale, for frequencies between 2 MHz and fc (4 MHz). (6) For system E this figure is reached at a frequency of 7 MHz and remains constant between 7 MHz and fc (10 MHz). (6) For colour in system M (Japan), the signal-to-noise ratio should not be less than 50 dB at 3-6 MHz. Rec. 421-2 — 178 —

3.3.2 Periodic noise The signal-to-noise ratio for periodic noise is defined as the ratio, in decibels, of the peak-to-peak amplitude of the picture signal (see Fig. 2) to the peak-to-peak amplitude of the noise. Note. — This definition has so far been used in specification clauses dealing with single-frequency noises and with power-supply hum (including the fundamental frequency and lower-order harmonics), but it may also prove to be useful for any case in which two or more sinusoidal components are in harmonic relationship. The signal-to-noise ratio in the hypothetical reference circuit should not be less than the value given in Table II. 3.3.3 Impulsive noise The signal-to-noise ratio for impulsive noise is defined as the ratio, in decibels, of the peak-to-peak amplitude of the picture signal (see Fig. 2) to the peak-to-peak amplitude of the noise. Provisionally, for the hypothetical reference circuit, a minimum signal-to-noise ratio of 25 dB for impulsive noise of a sporadic or infrequently occurring nature has been proposed for all systems, except system M (Canada and the United States of America), for which the requirement is 11 dB. 3.3.4 Crosstalk This matter is still under study. 3.4 Non-linear distortion Non-linear distortion affects both the picture and the synchronizing signals. Non-linear distortions of the picture signal may be classified under three headings *, namely: — field-time non-linear distortion, — line-time non-linear distortion, — short-time non-linear distortion. 3.4.1 Field-time non-linear distortion o f the picture signal This matter is still under study. 3.4.2 Line-time non-linear distortion o f the picture signal Non-linear of the picture signal is measured with Test Signal No. 3 (described in Annex I), using a superimposed sine-wave at a frequency 0-2 f c. The magnitude of the distortion is indicated by the ratio of the minimum peak-to- peak amplitude of the sine-wave to the maximum amplitude along the saw-tooth. The sine-wave may be displayed on an oscilloscope with the time base running at line frequency by using a band-pass filter to separate the sine-wave from the rest of the signal. The display then has the form indicated in Fig. 3 and the line-time non-linear distortion is indicated by changes in amplitude across the display.

M m

* The corresponding terms in French are respectively: distorsion de non-linearit6 aux frequences tres basses, aux frequences moyennes, aux frequences 61evees. — 179 — Rec. 421-2

The non-linear distortion should be expressed as a percentage, in the form (1 -m/M) x 1 0 0 and should not be more than 2 0 % for the hypothetical reference circuit. Alternatively, the result may, if desired, be expressed in dB in the form (20 log10 M/m) and for the hypothetical reference circuits should not exceed 2 dB. For system M (Canada and the United States of America), the non-linear distor tion is measured with a superimposed sine-wave of 0-143 V peak-to-peak at 3-6 MHz and the results are expressed either as a percentage or in dB and should not be more than 13% or 1-2 dB respectively. For colour in system M (Japan), using the same test signal, the differential gain should not exceed 10%, and the differential phase should not exceed 5°. 3.4.3 Short-time non-linear distortion o f the picture signal This matter is still under study *. In Canada and the United States of America, the short-time non-linear distortion requirement is covered by the non-linearity distortion requirement given in § 3.4.2. 3.4.4 Non-linear distortion o f the synchronizing signal For the hypothetical reference circuit, when the gain of the circuit is 0 dB, the amplitude, S, of the line-synchronizing signal, measured with Test Signal No. 3, should lie between the limits of 0-21 V and 0-33 V (0-26 V and 0-31 V for Canada and the United States of America), irrespective of whether the intermediate lines are at black level, Sa, or at white level, S b. 3.5 Linear waveform distortion 3.5.1 Field-time waveform distortion 3.5.1.1 Systems B, C, D, E, F, G, H, K, L For the hypothetical reference circuit, using Test Signal No. 1 (described in Annex I) the received waveform displayed on an oscilloscope should lie within the limits of the mask shown in Fig. 4, provided that the oscilloscope is adjusted so that the half-amplitude points of the bar transitions coincide with Mj and M2, and the mid-points of the “black” and “white” portions coincide with A and B respectively.

1,10 T 1,00 T 0,90 250 ps | 250 p s !

0,50

A J 0

l/z field period J/2 field period F ig u r e 4 — Waveform response to Test Signal No. 1

* In several countries, such measurements are at present being made using Test Signal No. 3 with a higher value than 0-2 f c for the frequency of the superimposed sine-wave (see Doc. CMTT/41, Monte Carlo, 1958—Chairman’s Report). Rec. 421-2 — 180 —

3.5.1.2 System M In Canada and the United States of America, with Test Signal No. 1, the vari ations about the level B should not exceed ±5 % when the signal is unclamped or ± 1 % when the signal is clamped. In Japan, with Test Signal No. 1, the tolerances are the same as for the 625- and 819-line systems.

3.5.2 Line-time waveform distortion

3.5.2.1 System M In Canada and the United States of America, for the hypothetical reference circuit, using Test Signal No. 2 (described in Annex I), with a rise-time of IT (0-25 fjis), the received waveforms displayed on an oscilloscope should lie within the limits of the corresponding mask, similar to that shown in Fig. 5, but with a permitted variation about the level B of ± 1 %, provided that the oscilloscope is adjusted so that the half-amplitude points of the bar transitions coincide with Mx and Ma, and the mid-points of the “black” and “white” portions coincide with A and B respectively. In Japan, the conditions described below for the 625- and 819-line systems apply.

1.05 1,00 0.95

0.50

Figure 5 Waveform response to Test Signal No. 2

3.5.2.2 Systems B, C, D, E, F, G, H, K, L For the hypothetical reference circuit, using Test Signal No. 2 (described in Annex I), with a rise-time of T (it may be necessary to use a rise-time of IT for circuits which cut olf sharply close to the nominal upper video-frequency limit), the received waveform displayed on an oscilloscope should lie within the limits of the mask shown in Fig. 5, provided that the oscilloscope is adjusted so that the half-amplitude points of the bar transitions coincide with Mx and M2, and the mid-points of the “black” and “white” portions coincide with A and B respectively. — 181 — Rec. 421-2

3.5.3 Short-time waveform distortion 3.5.3.1 System M In Canada and the United States of America, where a test signal comprising a sine-squared pulse of half-amplitude duration 1/(2 / c) s is used, the output signal should have a first-overshoot amplitude (negative), leading or trailing, not greater than 13 % of the peak amplitude of the pulse. In Japan, the test procedure is the same as that described for systems B, C, D, E, F, G, H, K, L, the response being observed by means of the mask shown in Fig. 6 . For the chrominance channel, further study is required.

F ig u r e 6 Mask for waveform response to Test Signal No. 2 for system M (Japan)

3.5.3.2 Systems B, C, D, E, F, G, H, K, L Test Signal No. 2 is used, with a rise-time of T = 1/(2f c). The response is observed by means of one of the masks shown in Figs. 7 and 8 , the oscilloscope being adjusted so that M coincides with the middle of the rise, and the black and white levels coincide with the segments a and (3. If ringing is present in the regions a and (3, the peaks of the oscillations should be set symmetrically with respect to a and p. For the hypothetical reference circuit, the response should be within the limits of the appropriate mask as follows: — Fig. 7 for systems D, K. — Fig. 8 for systems B, C, E, F, G, H (see Note). Rec. 421-2 — 182 —

Note. — For system L, the mask for the waveform response to Test Signal No. 2 is provisionally the mask of Fig. 8 corresponding to the 819-line system E(fe = 10 MHz).

3.6 Steady-state characteristics 3.6.1 System M In Canada and the United States of America, the design-objective limits are shown by the lines B in Figs. 10 and 11, the lowest frequency to which these limits apply being 0 0025 f c.

Upper Lower IMS limit limit 1 1 j j

008 120 90 6 o j ( > 8 a ! 2 8 i ! 0-28 109 91 100 1 1 1 1 1 1 ! 1 1 1 1 1 1 > 1 105 95 I ! 1 1 1 i 1 U-

0,14 us

■ 06' -U- V -1L°. - 0,8 - 0,6 0,2 0,4 0,6 0,8 1 ,0 Ms

Figure 7

Provisional mask for waveform response to Test Signal No. 2 for systems D, K — 183 — Rec. 421-2

Mask formed by a part of the curve defined by: ± e = + 0-025 within the limits: e = + 0-2 and e = — 0-1 on the one hand, and e — ± 0-05 up to t — 1 [xs on the other hand.

F ig u r e 8 Mask for waveform response to Test Signal No. 2 o f systems B, C, E, F, G, H

60Hz 800kHz 3MHz 4MHz fc f c: nominal upper limit of video-frequency band

Figure 9 Limits for the attenuation/frequency characteristic of System M for colour television (Japan)

In Japan the limits are as indicated below for the 625-line and 819-line systems, the appropriate value of f c being 4 MHz. For colour, the attenuation/frequency limits are indicated in Fig. 9; the envelope-delay/frequency limits require further study. Rec. 421-2 — 184 —

3.6.2 Systems B, C, D, E, F, G, H, K, L For the hypothetical reference circuit, the limits of the attenuation/frequency and envelope-delay/frequency characteristics given in Figs. 10 and 11 may be found useful by designers. In these figures, the abscissae show a single parameter which is the ratio between the frequency and the nominal upper video frequency, f c, of the system considered (normalized frequency).

Figure 10 Limits for the attenuation/normalized-frequency characteristic for television systems Curves A: With nominal upper limits of the video-frequency band / c = 4 MHz, system M (Japan); 5 MHz, systems B, C, F, G, H; 6 MHz, systems D,K,L\ 10 MHz, system E. Curves B: For system M (Canada and the United States of America), fc — 4 MHz.

! Reference frequency

F ig u r e 11 Limits for the envelope-delayjnormalized-frequency characteristic for television systems Curves A: With nominal upper limits of the video-frequency band f. = 4 MHz, system M (Japan); 5 MHz, systems B, C, F, G, H; 6 MHz, systems D, K, L; 10 MHz, system E. Curves B: For system M (Canada and the United States of America), f c = 4 MHz. — 185 — Rec. 421-2

ANNEX I

TEST SIGNALS 1. Test Signal No. 1 Test Signal No. 1 is used in the measurement of field-time waveform distortion. As shown in Fig. 12 below, it comprises a square wave of field frequency superimposed upon line-synchronizing and blanking pulses. If desired, a field-synchronizing signal may be included and the pedestal may be omitted.

v — i 1.0

Line-synchronizing pulses

V2 field period y2 field period Figure 12 Test Signal No. 1 2. Test Signal No. 2 * Test Signal No. 2 is used in the measurement of insertion gain, line-time waveform distortion and short-time waveform distortion. As shown in Fig. 13, it comprises a half-line bar associated with line-synchronizing pulses. If desired, a field-synchronizing signal may be included. The interval between the half-line bar and the succeeding synchronizing pulse may be either 01 H or 0-2 H, where H is the line period. The pedestal may be omitted if desired. The precise shape and rise-time of each transition of the half-line bar may be determined by means of a shaping network, the design of which is based on “Solution 3” in a paper by W. E. Thomson (Proc. I.E.E., Part III, 99, 373 (1952)). Two alternative networks may be used giving rise-times of T and 2T, where T = l/(2/c), and f c is the nominal upper video- frequency limit of the system. (Annex IV of the paper by Thomson contains a description of the appropriate network.) If desired, an additional feature such as a sine-squared pulse, of shape and half amplitude duration determined by the above-mentioned shaping networks, or a high- frequency burst, can be added in the space marked A. For systems D and K, a sine-squared pulse of half-amplitude duration T or 2T is used.

* Considerable errors in measurement occur when using Test Signals Nos. 2 and 3, if the signal-to-noise ratio is less than 30 dB (see Doc. CMTT/2, Paris, 1962). Rec. 421-2 — 186 —

Rise-time T or IT, where T = — 2/c

F ig u r e 13 Test Signal No. 2

3. Test Signal No. 3 * Test Signal No. 3 is used in the measurement of non-linear distortion. As shown in Fig. 14, it is a signal in which the “picture” portion of every fourth line consists of a Superimposed sine-wave

Superimposed sine-wave

Sb s

(b) Intermediate lines at white level

F ig u r e 14 Test Signal No. 3

* Considerable errors in measurement occur when using Test Signals Nos. 2 and 3, if the signal-to-noise ratio is less than 30 dB (see Doc. CMTT/2, Paris, 1962). — 187 — Rec. 421-2

sine-wave of 01 V peak-to-peak amplitude superimposed on a saw-tooth, the three inter mediate lines being set either to black level or to white level by means of a switch at the sending end. If desired, a field-synchronizing signal may be included and the pedestal may be omitted. For measuring line-time non-linearity distortion, the frequency of the superimposed sine-wave is 0 - 2 f c. At the receiving end of a circuit, any variation of the sine-wave amplitude over the duration of the saw-tooth is taken as indicative of non-linearity distortion.

ANNEX II

LOW-PASS FILTER FOR USE IN MEASUREMENTS OF CONTINUOUS RANDOM NOISE

LI MM*

- l h 75 a 75 a C1 C2 C3 C4 :C5 C 6 !C7 I

F ig u r e 15

Nominal upper video-frequency limit: fc (MHz) 0)

L(p.H) C (pF) /(M H z)

1 14*38//c 4 9 7 -6 //c 1-8816 f c

2 7*673//c 27 2 3 / f c 1*1011 f c

3 8-600/f c 1950/fc 1*2290 f c

4 21 3 9 /fc

5 2815 /fc

6 2315 /fc

7 1291 /f c

t1) For system M (Canada and the United States of America), a value of f c = 4*2 M Hz is adopted for the design of the low-pass filter used for noise measurement. Rec. 421-2 — 188 —

fife dB fife dB

0-98 0 1 104 14-8

0-99 0-5 105 18-8

1 0 0 1-8 1-06 230

1 0 1 4-2 107 27-7

1 0 2 7-3 108 33-3

103 10-9 109 410 0 fl fc f2 CO Frequency Theoretical insertion loss A = 0-9 f 2 by design. Ringing frequency = f c by design. A = 0-9807/ c ft = 1-0897/ 0 F i g u r e 16 Note 1. — Each capacitance quoted is the total value, including all relevant stray capacitances, and should be correct to ± 2 %. Note 2. — Each inductor should be adjusted to make the insertion loss a maximum at the appro priate indicated frequency, / (MHz). Note 3. — The theoretical insertion loss curve above corresponds to an infinite Q-factor. In practice, Q should be at least of the order of 100 at frequency f c. Note 4. — Limits for the insertion-loss/frequency characteristics are specified indirectly by the indicated tolerances on the component values.

ANNEX III

CONTINUOUS RANDOM-NOISE WEIGHTING NETWORKS

L (pH)

N m r -

■vww WW- 75n 75n

7 5 n - 75a C CpF)

L (txH) = 7 5 t ([xs); C (pF) = ^ • 108

Insertion loss (dB) = 10 log10 [1 + (2jtt/)2]

F i g u r e 17 — 189 — Rec. 421-2

Theoretical weighting (dB), for: System /(* ) (MHz) r (ps) r/c “Triangular” “White” noise noise M (Canada and U.S.A.) see Note 1 6-1 1 0 -2

M (Japan) 4 0-415 1-6 6 8-5 16-3

B, C, G, H 5 0-33 1-6 6 8-5 16-3

D, K, L 6 0-33 2 -0 9-3 17-8

F 5 0-33 1-6 6 8-5 16-3

E 10 0-166 1-6 6 8-5 16-3

(!) f c is the nominal upper video-frequency limit of the system (MHz).

Note 1. — For system M (Canada and the United States of America), the following weighting characteristic is used:

Frequency (MHz) 001 0-05 0-10 0-50 1-00 2-00 3-00 4-00

Weighting (insertion loss) (dB) 0 0 0-3 2-8 4-7 8-1 10-8 13-0

A weighting network, such as that shown below, may be used:

Insertion loss (dB) = 10 log! [1 + (//A)2] [1 + (///2)2] 310 [i + mm where:/x = 0-270 MHz, / 2 = 1-37 MHz and f z — 0-390 MHz

F i g u r e 18 Rec. 421-2 — ,190 —

Note 2. — For system M (Japan), the weighting curve of Fig. 19 is used for colour (see Watanabe, K. Effects of continuous random noise on colour television pictures. Electrical Telecomm. Laboratory. Report No. 1528, N.T.T., Japan (1964)).

MHz

Video frequency (MHz)

F ig u r e 19 Weighting curve for continuous random noise of a 525-line television system — 191 — Rec. 421-2

ANNEX IV

CIRCUITS HAVING MORE OR FEWER VIDEO SECTIONS THAN THE HYPOTHETICAL REFERENCE CIRCUIT

1. Introduction The purpose of this Annex is to give some indication of the design objectives of hypo thetical circuits that have more or fewer video-to-video sections than the three sections of the hypothetical reference circuit defined in § 1.2 of this Recommendation. The values calculable from Tables I and II provide only indications of the probable design objectives, which should be used with caution when considering specifications of actual circuits, because the law of addition is not precisely known for every type of impairment.

2. Laws of addition If Ds : design objective as expressed in this Recommendation, or the parame ter derived therefrom and indicated in Table II, permitted in the hypothe tical reference circuit, and Dn : design objective, or the parameter mentioned above, permitted in n sections,

then A i = As (y )

where h has the value 1, 3/2 or 2 in accordance with Table II; h = 1 gives linear or arithme tic law of addition, h = 3/2 gives the “three-halves power” law of addition, and h — 2 gives r.s.s. or quadratic addition.

/ n \ ijh Calculated values of 1^-1 , are given in Table I.

T a b le I

(t ) n m h = 1 h = 3/2 h = 2

i 0-33 0-48 0-58 2 0-67 0-76 0-82 3 1 0 0 1 0 0 1 0 0 4 1-33 1-21 1-15 5 1-67 1-41 1-29 6 2 -0 0 1-59 1-41 7 2-33 1-76 1-53 8 2-67 1-92 1-63 9 300 2-08 1-73 10 3-33 2-23 1-83 11 3-67 2-38 1-91 12 400 2-52 2 0 0 13 4-33 2 -6 6 208 14 4-67 2-79 216 15 500 2-92 2-24 Rec. 421-2 — 192 —

T a b le II

Relevant D § of this Characteristic expressed8 in h Note Recommendation

3.1 Insertion gain (tolerance) dB 2

3.2 Insertion gain variation short period dB 2 medium period dB 2

3.3.1 Continuous random noise 1

3.3.2 Periodic noise amplitude Power-supply hum of noise 2 2; 7 1 kHz to 1 MHz 2 3 1 MHz to f c 2 3

3.3.3 Impulsive noise amplitude 4 of noise

3.4 Non-linear distortion 3.4.2 Picture signal ( l - £ ) x 1 0 0 % 3/2 7 3.4.4 Synchronizing signal % 3/2

3.5 Linear waveform distortion 3.5.1 Field-time °/ 1 7 3.5.2 Line-time °/ 2 6 ; 7 3.5.3 Short-time overshoot and ringing mask 2 6 ; 7 Rise-time pLS no law 7

3.6 Steady-state characteristics Attenuation/frequency dB 3/2 5 Envelope delay/frequency (AS 3/2 5

Note 1. — For circuits on coaxial cables, quadratic addition {h = 2) applies to random noise expressed in terms of r.m.s. voltage. For circuits on radio-relay links, see Recommendation 289-1. Note 2 .— Considering the probability of arithmetic addition of power-supply hum in circuits of few sections, it may be advisable to put h — 1 when n ^ 3. Note 3. — Considering the probability of arithmetic addition when periodic noise consists of a few components that are very close in frequency, it may be advisable to put h = 1 , when the number of such components is small. Note 4. — When each of a number of sources of impulsive noise is operative for a small percentage of the time (e.g. < 0 1 %), arithmetic addition of the percentage will apply. Note 5. — In Canada and the United States of America, the practice is to use h = 2. Note 6. — For systems D and K, the method outlined in Doc. CMTT/60, 1963-1966, could be used. Note 7. — Further information is given in Doc. CMTT/49 (O.I.R.T.), 1966-1969. — 193 — Rec. 421-2, 451-1

3. Examples of the use of Tables I and II 3.1 In the hypothetical reference circuit, if the tolerance on gain is ±1 dB, the tolerance on gain for a video section will (with h = 2 ) be: ( iV k D1 = D3 \ — J = Z>3 x 0-58 = ±0-58 dB.

3.2 In the hypothetical reference circuit, if the tolerance on the signal-to-noise ratio is 50 dB, the tolerance on the signal-to-noise ratio for a 9-section circuit will be calculated as follows (with h = 2 ): noise amplitude for the hypothetical reference circuit :D3; noise amplitude for the 9-section circuit: / 9 \ Vs Dg — Dg f ) — Dg X 1’73

signal-to-noise ratio for the 9-section circuit: S_ _ J _ D9 ~ Ds 1-73

or, in dB: f — ) dB = 50 — 4-8, i.e. about 45 dB. \ -^9/ 3.3 In the hypothetical reference circuit, if the tolerance on non-linearity is 20%, the tolerance on non-linearity for a video section will be (with h = 3/2):

• / 1 \ % Dx = Z>3 ( — j = D3 x 0-48

Dy = 20 x 0-48 = 9-6%.

RECOMMENDATION 451-1

REQUIREMENTS FOR THE TRANSMISSION OF TELEVISION SIGNALS OVER LONG DISTANCES (SYSTEM I ONLY)

The C.C.I.R., (1966 - 1970)

CONSIDERING the agreement reached by the Joint C.C.I.R./C.C.I.T.T. Study Group for Television and Sound Transmissions (CMTT) on a draft Recommendation concerning television trans missions over long distances, common to the C.C.I.R. and C.C.I.T.T;

UNANIMOUSLY RECOMMENDS that, taking account of the definitions in Part 1, television transmissions over long distances for system I should satisfy the requirements laid down in Part 2 and its Annex. The requirements for the transmission of other systems are contained in Recommenda tion 421-2 and Report 316-1. The existence of this new Recommendation does not necessarily imply that the requirements for other systems will later be included in this Recommendation or that their requirements will be changed in form. Rec. 451-1 — 194 —

PART 1 — DEFINITIONS

1. Definition of a long-distance international television connection (see Fig. 1 of Recommendation 421-2). 1.1 Point A, to be considered as the sending end of the international television connection, may be the point at which the programme originates (studio or outside location), a switching centre or the location of a standards converter. 1.2 Point D, to be considered as the receiving end of the international television connection, may be a programme mixing or recording centre, a broadcasting station, a switching centre or the location of a standards converter. 1.3 The local line AB connects point A to the sending terminal station, point B, of the inter national television circuit. 1.4 The long-distance international television circuit, BC, comprises a chain of national and international television links. The precise locations (e.g. within buildings), to be regarded as the points B and C, will be nominated by the authorities concerned. 1.5 The local line CD connects point C, the receiving terminal station of the long-distance inter national television circuit, to the point D. 1.6 The combination AD, of the long-distance international television circuit, BC, and the local lines AB and CD, constitutes the international television connection.

2. Definition of the hypothetical reference circuit

The main features of the television hypothetical reference circuit, which is an example of a long-distance international television circuit (BC in Fig. 1 of Recommendation 421-2) and which may be of either radio or coaxial-cable type, are: — the overall length between video terminal points is 2500 km (about 1600 miles), — two intermediate video points divide the circuit into three sections of equal length, — the three sections are lined up individually and then interconnected without any form of overall adjustment or correction, — the circuit does not contain a standards converter or a synchronizing-pulse regenerator. Note. — The Annex to Part 1 gives a provisional indication of the characteristics of circuits having more or fewer sections than the hypothetical reference circuit. — 195 — Rec. 451-1

ANNEX TO PART 1

CIRCUITS HAVING MORE OR FEWER SECTIONS THAN THE HYPOTHETICAL REFERENCE CIRCUIT

1. Introduction The purpose of this Annex is to give some indication of the design objectives of hypothetical circuits that have more or fewer video-to-video sections than the three of the hypo thetical reference circuit defined in § 2 of Part 1 of this Recommendation. The values calculable from Tables I and II provide only indications of the probable design objectives, which should not be used directly when studying the design of equipment because the law of addition is not precisely known for every type of impairment.

2. Laws of addition

If Z>3 : design objective as expressed in this Recommendation, or the parameter derived therefrom and indicated in Table II, permitted in the hypothetical reference circuit, and Dn : design objective, or the parameter mentioned above, permitted in n sections, I n \1Ih then Dn = D 3, I ■

where h has the value 1, 3/2 or 2 in accordance with Table II; h = 1 gives linear or arithmetic law of addition, h = 3/2 gives the “three-halves power” law of addition, and h = 2 gives quadratic (r.s.s.) addition. ( n Calculated values of 1 — 1 are given in Table I.

T a b l e I

n h = 1 h = 3/2 h = 2

i 0-33 0-48 0-58 2 0-67 0-76 0-82 3 1 0 0 1 0 0 , 1 0 0 4 1-33 1-21 115 5 1-67 1-41 1-29 6 2 0 0 1-59 1-41 7 2-33 1-76 1-53 8 2-67 1-92 1-63 9 3 00 2-08 1-73 1 0 3-33 2-23 1-83 11 3-67 2-38 1-91 12 400 2-52 2 0 0 13 4-33 2 -6 6 2-08 14 4-67 2-79 2-16 15 5-00 2-92 2-24 Rec. 451-1 — 196 —

T a b l e II

§ of Part 2 Characteristic -Da expressed in h Notes

4.1 Insertion gain (error) dB 2 4.2 Insertion gain variations dB 2 Continuous random noise 4.3.1 Luminance channel 1 4.3.2 Chrominance channel 1 Periodic noise 4.4 Power-supply hum 1 noise 1 2 2 4.4 Single-frequency \ voltage i 2 3 4.5 Impulsive noise noise voltage 4 4.6 Crosstalk crosstalk voltage 3/2 Non-linear distortion of the picture signal 4.7.1 Luminance channel % 3/2 Chrominance channel 4.7.2 Differential gain % 3/2 4.7.2 Differential phase degrees 3/2 4.8 Non-linear distortion of the synchronizing signal °//o 3/2 Linear waveform distortion 4.9.1 Luminance channel °//o 3/2 4.9.2 Chrominance channel °// 0 3/2 Luminance-chrominance inequalities 4.10.1 Gain inequality / o 2 5 4.10.2 Delay inequality ns 2 5 Steady-state characteristics — Attenuation/frequency Envelope delay/frequency

Note I, — For circuits on coaxial cables, quadratic addition (h = 2) applies to random noise expressed in terms of r.m.s. voltage. For circuits on radio-relay links, see Recommendation 289-1. Note 2. — Considering the probability of arithmetic addition of power-supply hum in circuits of few sections, it may be advisable to put h = 1 when n < 3. Note 3. — Considering the probability of arithmetic addition when periodic noise consists of a few components that are very close in frequency, it may be advisable to put h = 1 when the number of such components is small. Note 4. — When each of a number of sources of impulsive noise is operative for a small percentage of the time (e.g. < 0 1 %), arithmetic addition of the percentages will apply. Note 5. — Quadratic addition (h = 2) for gain and delay inequalities is based on the assumption that , positive and negative values are made equally likely by the use of correcting networks or equivalent means. — 197 — Rec. 451-1

PART 2 — REQUIREMENTS FOR SYSTEM I

1. Introduction In this Part are given the methods of testing and the limits and tolerances applicable to the hypothetical reference circuit for system /, i.e. the 625-line system having a nomina video bandwidth of 5-5 MHz.

2. Basic concepts

The requirements are based upon two concepts. The first follows from the fact that thle composite colour signal may be regarded as the sum of a luminance signal (similar to a monochrome signal, including the line- and field-synchronizing pulses) and a chrominance signal (the modulated sub-carrier conveying the hue and saturation information, and the colour burst). A colour-television link may therefore be regarded as the combination of a “luminance channel” and a “chrominance channel” in overlapping frequency bands. For both specifying and testing purposes, it is convenient to deal with: — the permissible distortion and noise impairments in these two channels taken separately; — the permissible inequalities of gain and delay of the two channels taken in association. The requirements for the luminance channel are assumed to be identical with those for mopochrome transmission. The second concept is based upon the consideration that it is sufficient in practice to specify and test the performance of the chrominance channel as though it were intended to carry a simple double-sideband amplitude-modulated signal. The test signals thus include sub-carrier elements modulated by waveforms chosen to suit the nominal bandwidth of the chrominance channel. Applying these concepts to system / for the purpose of this Recommendation, the luminance-channel band is deemed to extend up to 5 MHz, and the chrominance-channel band from approximately 3-5 to 5-5 MHz, i.e. the baseband of the chrominance signal is deemed to extend up to 1 MHz. These assumptions do not imply restrictions upon the trans mission of any luminance-signal components in the range 5 0 to 5-5 MHz, or chrominance- signal components below 3-5 MHz.

3. General requirements

3.1 Impedance

At points of video interconnection, the input and output impedance of each link should be unbalanced to earth with a nominal value of 75 U resistive and a return loss of at least 30 dB relative to 75 U. The conventional frequency-domain interpretation of this requirement is that the return loss should be at least 30 dB at any frequency within the video band. A time-domain interpretation is, however, more convenient and useful because the technique of measure ment is simpler and the results are more directly related to the picture impairments caused by mismatched impedances. The “waveform return loss”, as it may be termed, is measured with a television-type test signal and the result is taken as the ratio, expressed in decibels, of the peak-to-peak voltages of the “picture” portions of the incident and reflected wave forms. This result is numerically the same as the conventional one if the return loss is inde pendent of frequency. Provisionally, it is required that the waveform return loss, relative to 75 H, shall be at least 30 dB when measured with each of the test signals shown in Figs. 1, 2 and 4. Rec. 451-1 — 198 —

3.2 Polarity and d.c. component At points of video interconnection, the polarity of the signal should be “positive”, i.e. such that black-to-white transitions are positive-going. The useful d.c. component, which is related to the average luminance of the picture, may or may not be contained in the signal and need not be transmitted or delivered at the output. Any non-useful d.c. component unrelated to the signal (e.g. the component due to d.c. supplies) should not cause more than 100 mW to be dissipated in a 75 Q. load impedance. If the load impedance is disconnected, the voltage of this component should not exceed 5 V.

3.3 Signal amplitude At points of video interconnection, the nominal peak-to-peak amplitude of the picture luminance signal, between blanking level and white level, should be 0-7 V, and the nominal amplitude of the synchronizing pulses should be 0-3 V. The nominal peak-to-peak amplitude of the video signal is thus TO V although it is recognized that this value may occasionally be exceeded during transmission of colour signals.

4. Transmission performance requirements 4.1 Insertion gain Insertion gain should be measured under the following conditions. At the sending end, a 75 f2 generator of the 2T pulse-and-bar test signal shown in Fig. 1 should be adjusted so that, if connected directly to a 75 O load, the bar amplitude would be 0-7 V and the synchro nizing pulse amplitude 0 3 V. The sine-squared pulse is ignored in this application. At the receiving end, the bar amplitude (between the points A and B shown in Fig. 10) should be measured with a 75 Q oscilloscope. The ratio, expressed in dB, of this amplitude to 0-7 V is taken as the insertion gain. After initial or routine adjustment, the insertion gain should be within the limits 0 ± 0-5 dB. .

4.2 Variations in the insertion gain Any variations of insertion gain with time should not exceed the following limits: — short-period variations (e.g. 1 s) ±0-2 dB; — medium-period variations (e.g. 1 h) ±0-5 dB. Long-period variations are not specified because they would generally be corrected by the normal routine adjustments. The foregoing refers only to insertion gain as defined in § 4.1. When considering variations of gain with time, the permissible limits of luminance-chrominance gain inequality given in § 4.10.1 should not be overlooked.

4.3 Continuous random noise The signal-to-weighted noise ratio for continuous random noise is defined as the ratio, expressed in dB, of the nominal peak-to-peak amplitude of the picture luminance signal to the r.m.s. amplitude of the noise measured under the following conditions: — the noise is passed through a specified bandpass filter to delimit the effective frequency range, and also through a specified weighting network, or equivalent; — the measurement is made with an instrument having, in terms of power, an effective time constant or integrating time of 1 s. — 199 — Rec. 451-1

4.3.1 Luminance channel The nominal frequency range is 10 kHz to 5 MHz. The lower limit is determined by the high-pass member of the junction filter shown in Fig. 6 ; its purpose is to exclude power-supply hum and microphony noise. The upper limit is determined by the low- pass filter shown in Fig. 7. The weighting network is shown in Fig. 8 ; it has a time constant of 200 ns giving a weighting effect of 6-5 dB for flat random noise and 12*3 dB for triangular random noise. The signal-to-weighted noise ratio should not fall below 52 dB for more than 1 % of any month nor below 44 dB for more than 01 % of any month.

4.3.2 Chrominance channel The nominal frequency range is 3-5 to 5-5 MHz, determined by the combined bandpass filter and weighting network shown in Fig. 9. For each sub-carrier sideband, the filter provides a weighting effect which is approximately equal to that of the lumi nance weighting network in the 0 to 1 MHz band. The signal-to-weighted noise ratio should not fall below 46 dB for more than 1 % of any month nor below 38 dB for more than 01 % of any month.

4.4 Periodic noise The signal-to-noise ratio for periodic noise is defined as the ratio, expressed in decibels, of the nominal peak-to-peak amplitude of the picture luminance signal to the peak-to-peak amplitude of the noise. For power-supply hum including Iower-order harmonics, the signal-to-noise ratio should not be less than 35 dB. The measurement is made through the low-pass member of the junction filter shown in Fig. 6 . For single-frequency noise between 1 kHz and 5-5 MHz, the signal-to-noise ratio should not be less than 55 dB.

4.5 Impulsive noise The signal-to-noise ratio for impulsive noise is defined as the ratio, expressed in decibels, of the nominal peak-to-peak amplitude of the picture luminance signal to the peak-to-peak amplitude of the noise. For impulsive noise of a sporadic or infrequently-occurring nature, the signal-to-noise ratio should not be less than 25 dB.

4.6 Crosstalk Crosstalk between two circuits is measured with a specified video test-signal applied to the input of the disturbing circuit and an oscilloscope at the output of the disturbed circuit, which is otherwise quiescent. The signal-to-crosstalk ratio is defined as the ratio, expressed in decibels, of the nominal peak-to-peak amplitude of the picture luminance signal to the peak-to-peak amplitude of the “picture” portion of the crosstalk waveform. At present, definitive limits can be specified only for two particular cases; for other forms of crosstalk further study is required. The specifications given in the two following paragraphs are strictly applicable only when the disturbing circuit, as well as the disturbed circuit, is designed to transmit system / signals, but they may serve as a guide under comparable conditions of service with other systems. If the crosstalk is substantially undistorted, the signal-to-crosstalk ratio should not be less than 58 dB when measured with the test signal shown in Fig. 1 applied to the disturbing circuit. Rec. 451-1 — 200 —

If the crosstalk is substantially “differentiated” (i.e. crosstalk voltage proportional to frequency), the signal-to-crosstalk ratio should not be less than 50 dB when measured with the test signal shown in Fig. 4 applied to the disturbing circuit.

4.7 Non-linear distortion of the picture signal Line-time non-linearity distortions in the luminance and chrominance channels are measured with the test signal shown in Fig. 3, consisting of a 5-riser staircase, with super imposed sub-carrier, in every fourth line. Separate measurements are made with the three intermediate lines at black level and white level, and the higher value of distortion is taken as the result.

4.7.1 Luminance channel At the receiving end, the test signal is passed through a differentiating and shaping network (see Doc. CMTT/3, Monte Carlo, 1958), whose effect is to eliminate the sub-carrier and transform the staircase into a train of 5 pulses of approximately sine- squared shape with 2 ^s half-amplitude duration. Comparing the amplitudes of the pulses, the numerical value of the distortion is found by expressing the difference between the largest and smallest amplitude as a percentage of the largest. The distortion should not exceed 12%. In addition, when the test signal is sent at 3 dB above normal amplitude (i.e. 1-4 V peak-to-peak), the distortion should not exceed 24 %.

4.7.2 Chrominance channel At the receiving end, the sub-carrier is filtered from the rest of the test signal and its six sections are compared in amplitude and phase. Taking the blanking-level section of the sub-carrier as reference, the differential gain is defined as the largest departure from the reference amplitude, expressed as a percentage, and the differential phase is defined as the largest departure from the reference phase-angle, expressed in degrees. (It seems desirable to seek a method of deriving numerical values which are more closely related to picture impairment.)

Provisionally, the differential gain should not exceed ± 8 % and the differential phase should not exceed ±4°. In addition, when the test signal is sent at 3 dB above normal amplitude, the distortions should not exceed ±16% and ± 8 ° respectively.

4.8 Non-linear distortion o f the synchronizing signal The distortion is expressed in terms of percentage departure of the mid-point amplitude of the line-synchronizing pulse from its nominal amplitude, i.e. 0-3 V for a circuit having zero insertion gain as defined in § 4.1. Using the staircase test signal shown in Fig. 3, separate measurements are made with the three intermediate lines at black level and white level, and the higher value of distortion is taken as the result. The distortion should not exceed ±10%. In addition, when the test signal is sent at 3 dB above normal amplitude, the distortion should not exceed ±20%.

4.9 Linear waveform distortion * 4.9.1 Luminance channel The short-time, line-time and field-time linear distortions in the luminance chan nel are found from the waveform responses to the pulse-and-bar and 50 Hz square-wave test signals shown in Figs. 1 and 2. The result is expressed as a rating factor K by the method described in the Annex to Part 2. The rating factor should not exceed 3 %. — 201 — Rec. 451-1

4.9.2 Chrominance channel The short-time and line-time linear distortions in the chrominance channel are found from the waveform responses to the pulse-and-bar modulated sub-carrier test signal shown in Fig. 4. The result may be expressed by a rating factor analogous to that of the luminance channel but a limit cannot be proposed until more experience has been gained.

4.10 Luminance-chrominance inequalities Gain and delay inequalities between the luminance and chrominance channels are measured with the composite test signal shown in Fig. 5. It consists essentially of added luminance and chrominance signal elements which are equal in single-peak amplitude and coincident in time. At the receiving end, two calibrated variable networks are adjusted to annul any inequality of amplitude or delay.

4.10.1 Gain inequality The gain inequality, expressed as the percentage departure of the amplitude of the chrominance element from the amplitude of the luminance element, both measured at the-mid-point of the bar, should not exceed ± 1 0 %.

4.10.2 Delay inequality The delay inequality should not exceed ±100 ns. A 451-1 — 202 —

ANNEX TO PART 2

LINEAR WAVEFORM DISTORTION, LUMINANCE CHANNEL 1. Introduction This Annex describes two complementary methods of specifying the linear transmis sion performance of a luminance channel. The first, or “routine-test method”, is rapid but less precise because it relies on direct oscilloscopic observation of the responses to prescribed test signals, and because the spectrum of one of these signals unavoidably extends beyond the nominal 5 MHz limit of interest. The second, or “acceptance-test method”, is slow but more precise because a process of computation applied to a series of waveform ordinates enables irrelevant information to be eliminated and certain measuring equipment errors to be corrected. . The performance limits are given in terms of a rating factor, K, for which numerical values are assigned in the individual specifications of links and equipment. Rating factors may range from 0-5 % (K = 0 005) for a short-distance link up to several percent for a chain of long-distance links.

2. Routine-test method To meet a specified rating factor, K, the responses to the pulse-and-bar and 50 Hz square-wave test signals shown in Figs. 1 and 2 should fall within the following limits.

2.1 2T bar response

The limits are indicated by the oscilloscope mask shown in Fig. 10. In effect, the oscillo scope is to be adjusted so that the half-amplitude points of the bar transition coincide with Mx and M2, and the mid-points of the H/2-5 “black” and “white” portions coincide with A and B respectively. The response should then fall within the ±K limits indicated by the full lines, which extend to Hj 100 from the half-amplitude point of each transition.

2 . 2 2Tpulse response The limits are indicated by the oscilloscope mask shown in Fig. 11. In effect, the oscilloscope is to be adjusted so that: — the sweep velocity corresponds with the time scale indicated; — the “ black” level of the response coincides with the horizontal axis; — the peak of the response falls on the unit-amplitude line; — the half-amplitude points of the response are symmetrically disposed about the vertical axis.

2.3 2Tpulse/bar ratio The ratio of the amplitude of the 2T pulse response to the amplitude of the 2T bar response should fall within the limits 1/(1 ± 4 K), where the pulse amplitude is the difference between the “black” level and the peak of the response, and the bar amplitude is the difference between the points A and B already defined. The limits are included in the mask shown in Fig. 10.

2.4 Tpulse response To meet the luminance-channel requirements, the T pulse response should not show appreciable ringing at a frequency below 5 0 MHz, irrespective of the assigned rating factor. This is only of academic interest for system I because the chrominance-channel requirements are such that the ring frequency should not be less than 5-5 MHz. — 203 — Rec. 451-1

Other limits cannot be specified rigidly because the spectrum of the T pulse extends far beyond 5 MHz, and the response must therefore contain irrelevant information. A partial solution is found in the insertion of a “5-3 MHz link filter” between the link and the oscilloscope. This is a member of a series of delay-equalized low-pass filters designed to have good waveform responses; its insertion loss is almost constant up to 5 0 MHz, thence increases by about 3 dB at 5-3 MHz (the ring frequency) and 20 dB at 5-7 MHz. Being dominant in determining the overall upper cut-off characteristic, it substantially attenuates the irrelevant components of the response. The T pulse/bar ratio of the overall response is then a useful feature for measurement; it is closely related to the ratio which forms the basis of restriction (3) in the acceptance-test method (§ 3.2). It has been found empirically that, to meet a specified rating factor, K, the T pulse/bar ratio of the link plus filter should fall within the limits 0-84/(1 ± 6 K). Thus, for a rating factor of 1 %, the ratio should be between 79 % and 89 %. As the formula indicates, a ratio of 84 % is given by the filter alone. Other features of interest in the T pulse response of the link plus filter are the lobes of ringing immediately before and after the main lobe of the response. The following is a rough guide to the maximum amplitudes to be expected under normal conditions:

Upper limit of lobe amplitude expressed as percentage of bar amplitude Lobe K = 1% K = 5%

First lobe (negative), leading or trailing .... 12 20

Second lobe (positive), leading or trailing . . . 8 12

Although the amplitudes of other lobes may be of importance in some cases, it is not possible to offer further general guidance at present.

2.5 50 Hz square-wave response The limits are indicated by the oscilloscope mask shown in Fig. 12. As for the 2T bar response, the oscilloscope is to be adjusted So that the waveform passes through the four marked points, the line-synchronizing pulses being ignored.

3. Acceptance-test method

3.1 2T bar response The limits are identical with those given in § 2.1 for the routine-test method.

3.2 T pulse response From the measured T pulse response and the measured or assumed response of the measuring equipment itself, the “filtered impulse response” is derived and expressed in the form of a normalized time series (see N.W. L e w is , Proc. I.E.E., Vol. 101, Part III, (1954)). The “main” term of this series represents the ideal or non-distorting part, and the “echo” terms represent the distorting part. To meet a specified rating factor, K, the amplitudes of the echo terms should be such that each of the following four restrictions is met. Rec. 451-1 — 204 —

Let the time series representing the filtered impulse response be

B(rT) B -r ^ + 1 • • and assume that this has already been normalized so that B0 = 1. Let the serial product of B(rT) and the series [l/2, 1, V2] be C(rT) = ... C—r, .. . C—!, C0, C+i,...... C+r, ......

where Cr = Vi^r- 1 + Br+ y2Br + 1

Restriction (1) is then given by

1 CV r = ± 1 Cn

and

Cr Cn

and

Cr < is: C,

Restriction (2) is given by

1 1 + 8 - 1 4 ^ 0 - 8

Restriction (3) is given by

y ,B r \ - 1 6

Restriction (4) is given by + 8 1}

The series C(rT) represents fairly closely the response to a 2T pulse. Restriction (1) is thus approximately equivalent to the limits indicated in Fig. 11 for the 2T pulse response in the routine-test method. Restriction (2) is similar to the limits placed on the 2T pulse/bar- ratio in the routine-test method. Restriction (3) is equivalent to limits placed on the pulse/bar- ratio of the response to a hypothetical pulse-and-bar test signal in which the pulse is an ideal filtered impulse. Restriction (4) is an upper limit placed on the average amplitude, ignoring signs, of the 16 central echo terms. — 205 — Rec. 451,1

3.3 50 Hz square-wave response The limits are identical with those given in § 2.5 for the routine-test method.

4. Gain/frequency characteristic As a precaution against possible overloading effects, the insertion gain at any frequency between 50 Hz and 5 MHz should not exceed the gain at the line-repetition frequency by more than an amount in dB numerically equal to the percentage rating factor e.g. 1 dB for a rating factor of 1 % (K = 0 01).

A B

3 S

4,7^s 12,3fJts 15ias ?5(iS 7(jls

' 64;xs

F ig u r e 1

T and 2Tpulse-and-bar test signals

(For insertion gain, and short-time and line-time linear distortions in the luminance channel)

A: T pulse or IT pulse B : T bar or IT bar T - 100 ns

Note. — For the design of the shaping-network, see M acD iarmid and Phillips, Proc. I.E.E. Vol. 105B, 440 (1958). Rec. 451-1Rec.

0,3V 0,7V Fr field-timeluminancethe channel)in distortion linear (For A: Optional colour Optional burst A: : Superimposedsub-carrier (4-43B: MHz) C: 3 lines at black levelblack 3lines white 3linesat or level at C: 0 s 0 ms 10 ms 10 (For alldistortions)non-linear (For 50 Hz square-waveHz 50 testsignal Staircasetestsignals 26 — 206 — F F gure r u ig gure r u ig 3 2

— 207 — Rec. 451-1

Modulated sub-carrier (4-43 MHz)

10,5pis

64jxs

F ig u r e 4

Tc and 2TC pulse-and-bar test signals (For short-time and line-time linear distortions in the chrominance channel) Tc = 500 ns

Note. — For the design of the shaping-network, see M acDiarmid and P h i l l i p s , Proc. I.E.E., Vol. 105B, 440 (1958).

Added luminance and chrominance 2Tc pulse-and-bar elements

Composite test signal (For luminance-chrominance gain and delay inequalities) Tc = 500 ns Rec. 451-1 208

C1 C2

A: Input B: High-pass output C: Low-pass output

T a b l e o f v a l u e s

Component Value Tolerance Cl 139 000 C2 196000 ±5 % C3 335 000

C4 81 2 0 0 LI 0-757 L2 3-12 ± 2 % L3 1-83 L4 1-29

Note 1. — Inductances are given in mH, capacitances in pF. Note 2. — The Q-factor of each inductor should be equal to, or greater than, 100 at 10 kHz.

Frequency (kHz)

F i g u r e 6 Junction filter (For noise measurement) — 209 — Rec. 451-1

LI L2 L3

Component Value Tolerance

Cl 1 0 0 Cl 545 C3 390 Note 2 C4 428 C5 563 C6 463 Cl 259 LI 2 -8 8 Note 3 L2 1-54 L3 1-72 f t 9-408 /. 5-506 - /. 6-145

Note 1. — Inductances are given in pH, capacitances in pF, frequencies in MHz. Note 2. — Each capacitance quoted is the total value, including all relevant stray capacitances, and should be correct to ± 2 %. Note 3. — Each inductor should be adjusted to make the insertion loss a maximum at the appro priate indicated frequency. Note 4. — The Q-factor of each inductor measured at 5 MHz should be between 80 and 125.

Figure 7

5 20 Low-pass filter (For random noise in the luminance channel) /

Frequency (MHz) Rec. 451-1 — 210 —

T a b l e o f v a l u es

Component Value Tolerance

C l 2660

LI 15 ± 1 % R1 75 R2 75

Note 1. — Inductance is given in pH, capacitance in pF, resistance in ohms.

Note 2. — The Q-factor of inductor LI should be equal to, or greater than, 25 at 8 MHz.

Note 3. — Insertion loss = 10 log10 [1 + (2^t/)2] dB, where t = 200 ns.

Frequency (kHz)

F i g u r e 8 Weighting network (For random noise in the luminance channel) — 211 — Rec. 451-1

T a b l e o f v a l u e s

Component Value Tolerance Component Value Tolerance Cl 4960 C12 311-4

C2 89-47 C13 619-2 ± 1 % C3 292-1 C14 187-5 C4 715-8 LI 2-960 C5 1239-0 L2 4-814

C6 194-3 ± 1 % L3 6-650 C7 1182 L4 1-093 Note 2

C8 385-7 L5 2-149

C9 141-3 L6 0-7476 CIO 418-6 L7 0-9846 Cll 941-2

Note 1. — Inductances are given in [lH, capacitances in pF. Note 2. — L3 is adjusted to resonate with C6 , and L4 with C l at 4-428 MHz. LI, L2, L5, L6 and. L7 are adjusted to give maximum insertion loss at the appropriate indicated frequencies. Note 3. — The Q-factor of each inductor should be equal to, or greater than, 100 between 3 MHz: and 6 MHz.

Note 4. — The insertion loss is equal to, or greater than, 35 dB at frequencies above 6 MHz.

Figure 9 Band-pass filter and weighting network (For random noise in the chrominance channel>

2 3 4 Frequency (MHz) Rec. 451-1 — 212 —

1 /(1 - 4K) ■ 1 + K 4,00 ~ i 1—K~ 1 /(1 +4K) 0,64(is i 0,64[xs

0,50 M1 M2

—1 0 1 ri i i i _j

64n-s

F i g u r e 10 2T bar response and 2Tpulse/bar ratio

F i g u r e 11 2Tpulse response

Unit interval: 100 ns 213 — Rec. 451-1

-1 + 2K J L = 1,00 T-T k '

250 tis 250 us

- 0,50

Figure 12 50 Hz square-wave response Rep. 316-1 — 214 —

CMTT A: Reports REPORT 316-1 *

REQUIREMENTS FOR THE TRANSMISSION OF TELEVISION SIGNALS OVER LONG DISTANCES (Question 1-1/CMTT) (1963 - 1966) Introduction The Joint C.C.I.R./C.C.I.T.T. Study Group for Television and Sound Transmissions '(CMTT) has studied the problems which occur when transmitting colour television signals over long distances. The CMTT expressed the opinion that it would be desirable to have eventually a single Recommendation to cover both colour and monochrome transmissions. With this in view, the CMTT has examined Recommendation 421-2, item by item, to ascertain whether, in the light of present knowledge, special requirements for colour television transmissions will be necessary. The conclusions are laid down in the following paragraphs, which are numbered to correspond with those of Recommendation 421-2. Note. — The material of this Report has been taken into account in formulating Recommendation 421-2. 1. Definitions 1.1 Definition o f a long-distance international television connection As in Recommendation 421-2. 1.2 Definition o f the hypothetical reference circuit As in Recommendation 421-2. 2. Requirements at video interconnection points 2.1 Impedance The return loss should be raised to 30 dB. 2.2 Polarity and d.c. component As in Recommendation 421-2. 2.3 Signal amplitude A new text is required; however, more extensive study must be made before such a text can be drafted. 3. Transmission performance of the hypothetical reference circuit 3.1 Insertion gain As in Recommendation 421-2. 3.2 Insertion gain variations As in Recommendation 421-2. 3.3 Noise 3.3.1 Continuous random noise A new text is required. Three methods may be used to specify the circuit per formance:

* This Report was adopted unanimously. — 215 — Rep. 316-1

— study of a new weighting curve for the composite signal (luminance and chro minance) ; — use of a new weighting network (in addition to the existing monochrome network) for the composite signal (luminance and chrominance); — use of two separate weighting networks, one for the luminance channel and one for the chrominance channel. The second method is being tried out in Canada and the United States of America, while the third method is proposed by the United Kingdom (see Doc. CMTT/21, Paris, 1962). . 3.3.2 Periodic noise The existing text (Recommendation 421-2) should be amended or expanded. More comprehensive studies must be made before a new text can be drafted. Methods similar to those proposed in § 3.3.1 could be used to specify the characteristics. See also the documents related to Question 4-1/11. 3.3.3 Impulsive noise As in Recommendation 421-2. 3.3.4 Crosstalk This matter is still under study. 3.4 Non-linear distortion 3.4.1 Field-time non-linear distortion As in Recommendation 421-2.

1 Line-time non-linear distortion and short-time non-linear distortion 3.4.3 J A number of delegates felt that the characteristics of line-time and short-time nondinear distortion need not be specified separately. It was agreed that § 3.4.3 (Recommendation 421-2) should be regarded as applicable to differential gain and phase variations. These characteristics should be measured at the frequency of the colour sub-carrier. Four test signals were suggested for this measurement: — Test Signal No. 3, in which the frequency of the superimposed sine-wave is that of the colour sub-carrier (see Docs. CMTT/5 and CMTT/6 , Paris, 1962); — a staircase signal with a superimposed sine-wave at the frequency of the colour sub-carrier (see Doc. CMTT/21, Paris, 1962); — a sine-wave at line frequency, with another sine-wave at the frequency of the colour sub-carrier superimposed on it; — a test signal, derived from Signal No. 3 by modification of the amplitudes of the saw-tooth and of the sub-carrier (see Doc. CMTT/12, Paris, 1962). The gain variations could be conveniently found from the expression (1 -m/M), expressed as a percentage or in decibels. It may be advantageous, however, to express gain variations with respect to the gain at the blanking level or some other specified level. Phase variations would be obtained from the phase corresponding to the blanking level. In Canada and the United States of America, gain and phase variations of 1 -2 dB and ±2° respectively are accepted for NTSC signal transmission over the hypothetical reference circuit. The adequacy of these tolerances has been confirmed by subjective tests carried out in the United States of America and described in Doc. CMTT/56, 1963-1966. Differential gain and phase measurements, on many long-distance circuits under normal working conditions, have been made in the United States of America over a long period, and are detailed in Doc. CMTT/34, 1963-1966. Rep. 316-1, 410-1 — 216 —

3.4.4 Non-linear distortion o f the synchronizing signal For the hypothetical reference circuit, when the gain of the circuit is 0 dB, the amplitude OS) of the line-synchronizing signal, measured with Test Signal No. 3, should lie between the limits of 0-27 V and 0-33 V (0-26 V and 0-31 V for Canada and the United States of America), irrespective of whether the intermediate lines are at black level (Sa) or at white level (Sb). 3.5 Linear waveform distortion 3.5.1 Field-time waveform distortion As in Recommendation 421-2. 3.5.2 Line-time waveform distortion As in Recommendation 421-2. 3.5.3 Short-time waveform distortion The existing text (Recommendation 421-2) must be modified. It must take account of the short-time waveform distortion for the modulated sub-carrier. Doc. CMTT/21, Paris, 1962 and Doc. CMTT/32, 1963-1966, offer methods for determining this charac teristic. Further studies are required. 3.6 Steady-state characteristics An amendment is called for. Several types of test signals are proposed for the study of this characteristic: — use of a frequency-sweep signal (see Docs. CMTT/5 and CMTT/6 , Paris, 1962 and Doc. CMTT/32, 1963-1966); — use of a frequency multi-burst, as is the practice in Canada and the United States of America. This type of signal is also mentioned in Doc. CMTT/2, Paris, 1962. The tolerances for amplitude/frequency and envelope-delay/frequency characteristics will be more stringent than those accepted for monochrome signals in Recommendation 421-2. In Canada and the United States of America, the characteristics specified for colour television circuits are those used in monochrome television, with the tolerances slightly reduced in the region (±0-5 MHz) of the colour sub-carrier.

REPORT 410-1 *

SINGLE VALUE OF THE SIGNAL-TO-NOISE RATIO FOR ALL TELEVISION SYSTEMS (Question 1-1/CMTT and Study Programme 1-1B-1/CMTT)

(1966 - 1970) Recommendations 421-2 and 451-1 contain design objectives for continuous random noise. Various weighting characteristics and measuring methods are given. Doc. CMTT/18 (XI/62) (U.S.S.R.), 1963-1966, presents a further method of video noise measurement.

* This Report was adopted unanimously. — 217 — Rep. 410-1

With respect to the use of noise weighting networks three different principles can be found in C.C.I.R. documents. These are:

— use of two separate networks, one for luminance noise and one for chrominance noise; — use of one network for the composite signal (luminance and chrominance); — use of separate networks, one for monochrome and one for colour television noise weighting.

While the above design objectives, weighting characteristics and methods of measure ment are useful, it is thought that the international exchange of television programmes would be facilitated if differences among these items on video noise were minimized. Further study of the matter is required with a view to achieving unified treatment in terms of video noise weighting characteristics, signal-to-noise ratio requirements and measuring methods.

Docs. CMTT/5 (Canada) and CMTT/15 (United States of America), 1963-1966, point out a possible step towards reaching such a goal, namely, standardization of test conditions and parameters for the determination of the weighting characteristic. The conditions and parameters relating to the assessment of the quality of impaired television pictures under laboratory conditions enumerated in Report 405-1, are areas where standardization is important in connection with the experimental determination of weighting characteristics. The spectral content of the noise source employed in such determinations would appear to be another area where standardization is important, keeping in mind that noise spectra of specific shapes are encountered in practical television circuits.

Doc. CMTT/55 (United States of America), 1963-1966, gives examples of spectral characteristics of noise found in television links and utilizes this information in the evaluation of the usefulness to colour television of existing monochrome weighting characteristics.

Docs. CMTT/19 (Canada) and CMTT/132 and Corrigendum 1 (Canada), 1966-1969, discuss the apparent grouping of existing C.C.I.R. weighting networks into two groups: one centred about a time constant of 370 ns (for a single-section C.C.I.R.-type weighting network); and one centred about a time constant of 185 ns. To the first of the above groups belong television systems with weighting characteristics derived, apparently, from earlier experiments.

Based on published results [5] recommending a time constant of 160 ns for the mono chrome weighting networks of both the 525-line and the 625-line standards, Docs. CMTT/131 (United Kingdom) and CMTT/132 and Corrigendum 1 (Canada), 1966-1969, propose that a time constant, respectively of 200 ns and 185 ns be adopted for a C.C.I.R. luminance weighting network applying to both the 525-line and 625-line standards.

Doc. CMTT/160 (Italy), 1966-1969, shows the results of subjective tests carried out with the aim of determining a noise weighting curve for colour television signals (PAL system). The tests have been carried out under three different conditions of measurement to take into account the possible influence of the absolute value of the noise power on the video metric weighting curve. The proposed noise weighting curve is reproduced on Fig. 3 of Doc. CMTT/160 (Italy), 1966-1969; for the television systems B and G the theoretical weight ing, obtained according to the above curve, for white noise results in 8-4 dB and for trian gular noise in 12-7 dB. These theoretical weightings have been applied with satisfactory results to find one figure of signal-to-noise ratio independent of the noise spectral distribution (for the same picture quality) as shown in Doc. CMTT/159 (Italy), 1966-1969.

An analysis of these documents on noise weighting curves shows an approach to an agreement among the various experiments. This agreement centres on a noise weighting curve having a time constant in the vicinity of 2 0 0 ns.

Finally, a method for normalizing the presentation of the weighting characteristics in the different television systems would also be very helpful. Rep. 410-1, 486 — 218 —

In view of the progress being made in Report 486 on a unified Recommendation, Administrations are invited to consider these problems, with a view to reaching agreement by the XHIth Plenary Assembly.

B ibliography

1. C.C.I.R. Doc. CMTT/124 (Japan), Geneva, 1963. 2. C.C.I.R. Doc. CMTT/125 (Canada), Geneva, 1963. 3. K r ivo sh eev, M.I. Fundamentals of television measurements (in Russian). Moscow, Sviaz (1964). 4. A l l n a t t , J.W. and P rosser, R.D. Subjective quality of colour television pictures impaired by random noise. Proc. I.E.E. 113, 551-557 (April, 1966). 5. Y a m a g u c h i, Y . The visibility of monochrome television random interferences and its measure ments. NHK Technical Monograph. 11 (February, 1968).

REPORT 486 *

TRANSMISSION PERFORMANCE OF TELEVISION CIRCUITS DESIGNED FOR USE IN INTERNATIONAL CONNECTIONS (Question 1-1/CMTT and Study Programme 1-1B-1/CMTT)

Introduction (1970)

The Joint C.C.I.R./C.C.I.T.T. Study Group for Television and Sound Transmissions (CMTT) has studied problems which occur when transmitting television signals of various standards over long distances. The CMTT decided to study unified test methods and transmission performance which can be recommended for circuits intended for transmission of signals conforming to the majority of television standards (see Study Programme 1-1B-1/CMTT). It is considered that a unified Recommendation should be drafted for use where circuits will be required at various times to transmit television signals of the 525-line and the 625- line standards. The unified Recommendation need not apply to circuits which are required to transmit only signals of the 525-line standard. Discussions have indicated that such a Recommendation should contain the five parts described below. Contributions submitted during the 1966-1969 study period led to the preparation of nearly complete texts for Parts 1, 2 and 5, and a partial text of Part 3. These parts should be tested in practice and modified as required during the next study period. It was not possible during the 1966-1969 study period to define the limits and tolerances of the transmission parameters, as required for Part 4 of the Report. Attempts should be made to complete this section during the next study period.

* This Report was adopted unanimously. — 219 — Rep. 486

PART 1 — DEFINITION OF A LONG-DISTANCE INTERNATIONAL TELEVISION CONNECTION AND DEFINITION OF THE TERRESTRIAL AND ACTIVE COMMUNICATION SATELLITE HYPOTHETICAL REFERENCE CIRCUITS

1. Definitions Long distance international Local line television circuit Local line

International television connection

F ig u r e 1

1.1 Definition o f a long-distance international television connection (Fig. 1) 1.1.1 Point A, to be considered as the sending end of the international television connection, may be the point at which the programme originates (studio or outside location), a switching centre or the location of a standards converter. 1.1.2 Point D, to be considered as the receiving end of the international television connection, may be a programme-mixing or recording centre, a broadcasting station, a switching centre or the location of a standards converter. 1.1.3 The local line AB connects point A to the sending terminal station, point B, of the inter national television circuit. 1.1.4 The long-distance international television circuit, BC, comprises a chain of national and international television links. The precise locations (e.g. within buildings), to be regarded as the points B and C, will be nominated by the authorities concerned. 1.1.5 The local line CD connects point C, the receiving terminal station of the long-distance international television circuit, to the point D. 1.1.6 The combination AD, of the long-distance international television circuit, BC, and the local lines AB and CD, constitutes the international television connection. The requirements given in subsequent parts of this Report refer to the performance of long-distance international television circuits only; no requirements have been laid down for the local lines, AB and CD.

1.2 Definition o f the terrestrial hypothetical reference circuit The main features of the television hypothetical reference circuit, which is an example of a long-distance international television circuit (BC in Fig. 1) and which may be of either radio or coaxial cable type, are: — the overall length between video terminal points is 2500 km (about 1600 miles); — two intermediate video points divide the circuit into three sections of equal length; — the three sections are lined up individually and then interconnected without any form of overall adjustment or correction; — the circuit does not contain a standards converter or a synchronizing pulse regenerator. Rep. 486 — 220 —

1.3 Definition o f hypothetical reference circuit for active communication-satellite systems

Satellite link

Earth station Earth station Communication-satellite space station

F ig u r e 2 Hypothetical reference circuit for active communication-satellite systems

A hypothetical reference circuit for active communication-satellite systems contains the following characteristics: — it consists of one Earth-satellite-Earth link; — the circuit should include one pair of modulation and demodulation equipments for translation from the baseband to the radio-frequency carrier, and from the radio-frequency carrier to the baseband respectively; — the circuit does not contain a standards converter or a synchronizing-pulse regenerator.

PART 2 — DEFINITION OF PARAMETERS

1. Terminology The following terms are illustrated in Fig. 3:

M : Monochrome video signal—peak-to-peak amplitude. S : Synchronizing signal—amplitude. L : Picture luminance signal—nominal value. A : Non-useful d.c. component of the video signal. B : Useful d.c. component of the picture signal, integrated over a complete frame period. C : The d.c. component of the picture signal, during the active line period (Tu). D : The instantaneous amplitude of the luminance signal. E : The instantaneous value of the composite video signal. F : The peak amplitude of the colour signal (positive or negative with respect to blanking level). G : The peak amplitude of the chrominance signal. H : The peak-to-peak amplitude of the composite colour video signal. J : The difference between black level and blanking level. K : The peak-to-peak amplitude of the colour burst. — 221 — Rep. 486

The amplitudes M, S and L are used as reference amplitudes for the video signal. In particular, the amplitudes ofBto J above may be expressed as percentages of the value (L). Average picture level is the mean value of C over a complete frame period (exclud- < ing blanking intervals) expressed as a percentage of L.

2. Requirements at points of video interconnection 2.1 Nominal impedance At points of video interconnection, the input and output impedance of each link should be unbalanced to earth with a nominal value of 75 Q. resistive. 2.2 Return loss The return loss, relative to 75 fi, of an impedance Z is, in the frequency domain:

75 + Z ( /) 2 0 log10 dB 7 5 - Z ( / ) In the time domain, it is expressed by the symbolic formula:

A, 2 0 log10 dB

where Ax is the peak-to-peak amplitude of the incident picture signal and A2 is the peak-to- peak amplitude of the reflected picture signal. Numerically, the result is the same as that obtained by the frequency domain method if the return loss is independent of frequency.

2.3 Polarity and d.c. component The polarity of the signal should be “positive” , i.e. such that black-to-white transitions are positive-going. The useful d.c. component, B in Fig. 3, which is related to the average luminance of the picture, may or may not be contained in the signal and need not be transmitted or delivered at the output. A non-useful d.c. component, A in Fig. 3, may be present in the signal (for example, due to d.c. supplies). Limits for this component need to be specified for the terminated and unterminated conditions.

2.4 Nominal signal amplitude The nominal peak-to-peak amplitude of the video signal, M in Fig. 3, is 1 0 V.

3. Transmission performance requirements 3.1 Insertion gain The ratio, expressed in decibels, of the peak-to-peak amplitude of a specified test signal at the receiving end to the nominal amplitude of that signal at the sending end.

3.2 Noise

3.2.1 Continuous random noise The signal-to-weighted noise ratio for continuous random noise is defined as the ratio, expressed in decibels, of the nominal amplitude of the picture luminance signal, L in Fig. 3, to the r.m.s. amplitude of the noise measured after band limiting and weighting. The measurement should be made with an instrument having, in terms of power, a defined time-constant or integrating time. Rep. 486 — 222

3.2.2 Periodic noise

The signal-to-noise ratio for periodic noise is defined as the ratio, expressed in decibels, of the nominal amplitude of the picture luminance signal, L in Fig. 3, to the peak-to-peak amplitude of the noise. Different values are specified for noise at a single frequency between 1 kHz and the upper limit of the video frequency band and for power-supply hum including lower-order harmonics. 3.2.3 Impulsive noise The signal-to-noise ratio for impulsive noise is defined as the ratio, expressed in decibels, of the nominal amplitude of the picture luminance signal, L in Fig. 3, to the peak-to-peak amplitude of the noise. 3.3 Crosstalk from another television channel The signal-to-crosstalk ratio is defined as the ratio, expressed in decibels, of the nominal amplitude of the picture luminance signal, L in Fig. 3, to the peak-to-peak amplitude of the “picture” portion of the crosstalk waveform. 3.4 Non-linearity distortion In a long-distance television circuit the transmission characteristic may not be completely linear. The extent of the non-linearity distortion which is produced will depend on:

— the average picture level, as defined in § 1 ; — the instantaneous amplitude of the luminance signal (D in Fig. 3); — the amplitude of the chrominance signal {G in Fig. 3). There would, in general, be little purpose in attempting to define completely the non-linear characteristics of a transmission circuit. On the one hand, therefore, it is necessary to limit the number of measured quantities by restricting them to those which are recognized as being directly correlated'with picture quality. On the other hand, the test conditions should be restricted by introducing a systematic classification in the definition of the quantities to be measured. The form of the video signal is such that the effect of circuit non-linearity on the synchronizing signal is distinct from its effect on the picture signal. Furthermore, the non- linearity may affect the luminance and chrominance signals individually or cause interaction between them. This leads to the following system of classification of non-linear distortions: Non-linear distortion

Synchronizing signal (§ 3.4.2) Picture signal (§ 3.4.1)

Luminance signal Chrominance signal

Amplitude distortion Amplitude distortion Phase distortion

Due to luminance Due to chromi- Due to chromi- Due to luminance amplitude nance amplitude nance amplitude amplitude (differ- (§ 3.4.1.1) (intermodulation ) (§ 3.4.1.2) ential phase) (§ 3.4.1.4) (§ 3.4.1.3)

Due to chromi- Due to luminance nance amplitude amplitude (differ- (§3.4.1.2) ential gain) (§3.4.1.3) — 223 — Rep. 486

The above classification applies for steady-state conditions during a time span which is long in relation to the picture period. In this case the concept of average picture level has a precise significance. If these conditions are not fulfilled,- for example, if a sudden change in the d.c. component is introduced, additional non-linear effects may be produced, the extent of which will depend on the very low frequency transient response of the circuit. This aspect requires further study (see Study Programme 1-1D/CMTT).

3.4.1 Picture signal

3.4.1.1 Luminance signal For a particular value of average picture level, the non-linearity distortion of the luminance signal is defined as the lack of proportionality between the amplitude of a small unit step function at the input to the circuit and the corresponding amplitude at the output, as the level of the step is shifted from blanking level to white level.

3.4.1.2 Chrominance signal For fixed values of luminance signal amplitude and average picture level, the non-linear distortion of the chrominance signal is defined as the lack of proportionality between the amplitude of the chrominance sub-carrier at ^ -the input to the circuit and the corresponding amplitude at the output, as the amplitude of the sub-carrier is varied from zero to its maximum value.

3.4.1.3 Intermodulation from the luminance signal into the chrominance signal Differential gain If a constant small amplitude of chrominance sub-carrier, superimposed on a luminance signal, is applied to the input of the circuit, the differential gain is defined as the variation in the amplitude of the sub-carrier at the output as the luminance varies from blanking level to white level, the average picture level being maintained at a particular value.

Differential phase If a constant small amplitude of chrominance sub-carrier without phase modulation, superimposed on a luminance signal, is applied to the input of the circuit, the differential phase is defined as the variation in the phase of the sub-carrier at the output as the luminance varies from blanking level to white level, the average picture level being maintained at a particular value. 3.4.1.4 Intermodulation from the chrominance signal into the luminance signal If a chrominance signal is superimposed on a constant level of luminance signal and applied to the input of the circuit, the intermodulation is defined as the change in level of the luminance signal at the output when the chro minance signal is removed, the average picture level being maintained at a particular, value.

3.4.2 Synchronizing signal If a suitable video signal containing synchronizing pulses of the nominal amplitude is applied to the input of the circuit, the non-linear distortion is defined as the change in amplitude of the line synchronizing pulses at the output when the average picture is varied over a defined range.

3.5 Linear distortion 3.5.1 Waveform distortion o f the luminance signal The distortion of the video waveform due to a long-distance television circuit will in general be represented by a continuous function in the time domain. Rep. 486 — 224 —

In practice, however, the form of the video signal and the effects on a displayed picture are such that the resulting impairments may be classified by dividing the time scale into three segments which are comparable to the duration of one field, one line and one picture element respectively. In considering each of these segments, therefore, impairments appropriate to the other two segments are excluded by the measuring method. 3.5.1.1 Field-time waveform distortion If a square-wave signal with a duration of the same order as one field and of nominal picture amplitude is applied to the input of the circuit, the field-time waveform distortion is defined as the change in shape of the top of the square wave at the output. A period at the beginning and end of the square wave equivalent to the duration of a few lines is excluded from the measurement.

3.5.1.2 Line-time waveform distortion If a square-wave signal with a duration of the same order as one line and of nominal picture amplitude is applied to the input of the circuit, the line-time waveform distortion is defined as the change in shape of the top of the square wave at the output. A period at the beginning and end of the square wave equivalent to a few picture elements is excluded from the meas urement. 3.5.1.3 Short-time waveform distortion If a short pulse (or a rapid step function) of defined amplitude and shape is applied to the input of the circuit, the short-time waveform distortion is defined as the departure of the output pulse (or step) from its original shape. The choice of the half-amplitude duration of the pulse (or the rise-time of the step) will be determined by the nominal cut-off frequency (/c) of the system. 3.5.2 Waveform distortion o f the chrominance signal If a signal consisting of chrominance sub-carrier, modulated by a defined luminance test waveform is applied to the input of the circuit, the distortion is defined by the change in shape of the modulation envelope of the chrominance signal at the output. 3.5.3 Luminance-chrominance inequalities A composite signal, consisting of a defined luminance test signal in fixed ampli tude and time relationship with a chrominance sub-carrier modulated by the same luminance test signal, may be applied to the input of the circuit. The luminance signal at the output may be compared with the modulation envelope of the chrominance signal. The gain inequality of the circuit is defined as the change in relative amplitude of the two signals between input and output. The delay inequality of the circuit is defined as the change in relative timing of corresponding parts of the two waveforms between input and output.

3.5.4 Steady state characteristics 3.5.4.1 The gain/frequency characteristic of the circuit is defined by the variation in insertion gain over the frequency band extending from the field repetition frequency to the nominal cut-off frequency of the system, relative to the gain at a suitable reference frequency. 3.5.4.2 The envelope-delay/frequency characteristic of the circuit is defined by the variation in envelope delay between the input and the output of the circuit, over the frequency band extending from the field repetition frequency to the nominal cut-off frequency of the system, relative to the delay at a suitable refe rence frequency. It is for practical reasons, an approximation to the slope (derivative) of the phase/frequency characteristic of the circuit. 2 — e. 486 Rep. —225

Figure 3 Rep. 486 — 226 —

PART 3 — MEASURING METHODS AND TEST SIGNALS

1. Introduction

Section numbering in this part is related to section numbers of Part 2. In order to measure parameters not listed below, conventional methods can be used which require no further description. The test signal elements contained in Annex I may be combined in any suitable way to form test signals. Unless otherwise specified, the average picture level of test signals so obtained should be 50%. Test signals can be used either as repetitive signals or as insertion test signals in connec tion with picture lines chosen to give the required average picture level.

2.2 Return loss In order to measure return loss in the frequency domain, any of several well-established methods may be used. It is required that the return loss be equal to or greater than the value specified in Part 4 at any frequency within the video band. In order to measure return loss in the time domain, test signal elements A, B \ , B2 and F are used. This method requires that the waveform return loss for all of these signals be equal to or greater than the value specified in Part 4. The waveform return loss is defined as the ratio, expressed in decibels, of the peak-to- peak voltages of the picture portions of the incident and reflected waveforms of the test signal elements B\ or B2 respectively.

Note. — If the return loss to be measured is independent of frequency, the above methods will yield, numerically, the same result.

3.1 Insertion gain The signal element used is B2. The peak-to-peak amplitude is defined as the distance between point B in Fig. 4 and black level. The resulting value must remain inside the limits specified in Part 4. Note. — For system M, a test signal element similar to B2 but of shorter duration is used. 3.2 Noise

3.2.1 Continuous random noise Measuring equipment In general, measurements are made with r.m.s.-reading instruments. Depending on the type of instrument to be used, the circuit will carry either no signal or a specified repetitive signal. The latter case may be used if clamping devices have to be activated. The measuring instrument should have, in terms of power, an effective time constant or integrating time of 1 s. Note. — For system M (United States of America and Canada), a time constant of 0-4 s is used in this case. Noise measurements are also made using a specified line in the field-blanking interval which is kept free of picture information. In this case a different integrating time must be used. The value is still under study. When the measurements are made by assessing the quasi peak-to-peak ampli tude of the noise, Administrations are asked to determine the peak factor appropriate for their measuring methods and to express the results in terms of r.m.s. noise amplitude. — 227 — Rep. 486

Band limiting The measuring instrument will be preceded by a band-limiting filter, the atte nuation range of which is shown in Fig. 5. The lower band limit is such that power- supply hum and microphonic noise are excluded. The upper limit is so selected as to eliminate noise which occurs outside the wanted band of the video signal. The upper limit given in Fig. 5 is a compromise between the different standards used in interna tional exchange. Weighting The problems of noise-weighting filters and other aspects of noise measurements are still under study. (See Report 410-1). 3.2.2 Periodic noise Conventional measuring methods may be used. Measurements of power supply hum including lower-order harmonics should be made through a low-pass filter, the loss mask of which is shown in Fig. 6 . 3.3 Crosstalk from another television channel The measurement is made when there is no signal on the disturbed circuit. Measurements in the time domain The following combinations of test signal elements may be used: Bl + B2 B2 + E 2 Bl + B2 + F Different values are specified, depending on whether the crosstalk appears more or less uniformly throughout the frequency range of the interfering signal or selectively (differentially), affecting mainly the higher frequencies in the range. Measurements in the frequency domain Conventional methods may be used if a sinusoidal signal is used as the dis turbing signal. The resulting value must be equal to or greater than the value specified in Part 4 for any frequency of the video band. Note. — If the crosstalk to be measured is independent of frequency, all methods described above will yield, numerically, the same result. Rep. 486 — 228 —

Figure 4 Insertion gain

Frequency, MHz

Figure 5 Loss mask of the luminance band-limiting filter

Frequency, kHz

Figure 6 Loss mask of the low-pass filter used to measure power-supply hum — 229 — Rep. 486

ANNEX I TO PART 3

TEST SIGNALS An indication of the test signals so far mentioned in Part 3 of this Report is given below in the form of figures. For further details, reference should be made to Recommendation 473 (Insertion of special signals in the field-blanking interval of a television signal). The numerical values in the figures are proposed for all 625-line 50 field/sec systems. Some of them will have to be modified to apply to systems M (525-lines, 60 field/sec) and E (819-lines 50 field/sec). This Annex is as yet incomplete.

10 m s 10 m s 99699

Figure 7 Signal A

Signal B1 Signal B2

F i g u r e 8 ' Signal B Rep. 486 — 230 —

f = 4,43 MHz

t = 25 tis

Figure 9 Signal E2

Figure 10 Signal F — 231 — Rep. 486

ANNEX II TO PART 3

EXAMPLES OF THE DESIGN OF FILTERS USED TO MEASURE NOISE FOR VIDEO-FREQUENCY SIGNAL TRANSMISSION

1. Low-pass filter for use in noise measurements

L1 L2 L3

T a b l e o f v a l u es

Component Value Tolerance

Cl 1 0 0 C2 545 C3 390 Note 2 C4 428 C5 563

C6 • 463 C7 259

LI 2-8 8 Note 3 L2 1-54 L3 1-72 A 9-408 A 5-506 A 6-145

Note 1. — Inductances are given in g.H, capacitances in pF, frequencies in MHz. Note 2. — Each capacitance quoted is the total value, including all relevant stray capacitances, and should be correct to ± 2 %. Note 3. — Each inductor should be adjusted to make the insertion loss a maximum at the appro priate indicated frequency. Note 4. — The Q-factor of each inductor measured at 5 MHz should be between 80 and 125. Rep. 486 — 232 —

2. Combined high-pass, low-pass filter

The high-pass section is used in series with the low-pass filter described in § 1 fo r measuring continuous random noise. The low-pass section is used to measure power-supply hum.

C1 C2

A: Input B : High-pass output

T a b l e o f v a l u es

Component Value Tolerance

Cl 139 000

- C2 196 000 ±5% C3 335 000

C4 81 2 0 0

LI 0-757

L2 3-12 ± 2 % L3 1-83 L4 1-29

Note 1. — Inductances are given in mH, capacitances in pF. Note 2. — The Q-factor of each inductor should be equal to, or greater than, 100 at 10 kHz. — 233 — Rep. 486

PART 4 — LIMITS AND TOLERANCES (to be studied) PART 5 — ESTIMATION OF TRANSMISSION PERFORMANCE OF CIRCUITS SHORTER OR LONGER THAN THE HYPOTHETICAL REFERENCE CIRCUIT

1. Introduction The purpose of Part 5 is to give some indication of the design objectives of circuits that have fewer or more video-to-video sections than the sections of the hypothetical reference circuit defined in Part 1, § 1.2 * of this Report. The effect of the length and the configuration of the circuit relative to the hypothetical reference circuit is also considered. The values calculated from Tables I and II provide only indications of the probable design objectives. These values should not be used directly when studying the design of equipment because the law of addition is not precisely known for every type of impairment.

2. Laws of addition

2.1 Comments on the use o f the laws o f addition

The definition of a circuit in terms of a single multiple of the hypothetical reference circuit is impossible if the number of video-to-video sections and the length of the circuit differ from those of the hypothetical reference circuit by different ratios, i.e. if n/i =h Ljl where n = number of video-to-video sections L = length of the circuit I = 2500 km. In such cases two definitions of the circuit in terms of the hypothetical reference circuit should be used, one for those parameters primarily proportional to the circuit configuration, and a second for the parameter (continuous random noise) primarily proportional to length. It should however be recognized that there are limitations to the use of a multiple definition of a circuit and the following guidelines are suggested: — a single definition (encompassing all parameters) using n as the criteria for calculation (law given in § 2.2) should be used if £// = 0-5, a separate circuit definition should be used for “continuous random noise” . This definition should be obtained by use of the expression given in § 2.3. 2.2 Law pertaining to circuit configuration For a single definition of the circuit use the following equation for all parameters in Table II. For a double definition, exclude “continuous random noise”.

If Z>3 = design objective as expressed in this Report, or the parameter derived therefrom and indicated in Table II, permitted in the hypothetical reference circuit, and Dn = design objective, or the parameter mentioned above, permitted in n sections, j n \ ■*■/* then Dn = Dz ( y j where h has the value 1, 3/2 or 2 in accordance with Table II: h = 1 gives linear or arith metic law of addition, h = i l l gives the “three halves power” law of addition and h = 2 I n \ ■*■/* gives the quadratic (r.s.s.) law of addition. Calculated values of ( y 1 are given in Table I.

* The use of the following laws of addition for active communication-satellite links will not be possible until the satellite link performance has been defined in terms of the performance of the terrestrial hypothetical reference circuit. Rep. 486 — 234

2 .3 Law pertaining to circuit length Use the following equation for the second definition of the circuit in terms of the hypothetical reference circuit for “continuous random noise voltage” only. When distance is considered the law of addition becomes ( L \ 1jh A, = D, (j)

where D n, Do, L and I are as defined in §§ 2.1 and 2.2.

T a b l e I

n (t )'" h = 1 h = 3/2 h = 2

i 0-33 0-48 0-58 2 0-67 0-76 0-82 3 1 0 0 1 0 0 1 0 0 4 1-33 1-21 1-15 5 1-67 1-41 1-29 6 2 0 0 1-59 1-41 7 2-33 1-76 1-53 8 2-67 1-92 1-63 9 300 208 1-73 1 0 3-33 2-23 1-83 11 3-67 2-38 1-91 1 2 400 2-52 2 0 0 13 4-33 2 -6 6 208 14 4-67 2-79 216 15 500 2-92 2-24

/ — 235 — Rep. 486

T a b l e II

§ of Part 2j Characteristic Dz expressed in AC) Notes 3.1 Insertion gain (error ) dB 2 Insertion gain variations dB 2 3. 2.1 Continuous random noise 1 3.2.2 Periodic noise Power-supply hum j Noise 2 2;7 Single frequency \ voltage 2 3 3.2. 3 Impulsive noise Noise voltage 4 3.3 Crosstalk Crosstalk voltage 3/2 3.4.1 Non-linear distortion of the picture signal Luminance % 3/2 Chrominance Differential gain % 3/2 Differential phase Degrees 3/2 3.4.2 Non-linear distortion of the synchronizing signal % 3/2 3.5. 1 Linear waveform distortion Field-time % 1 Line-time % 2 Short-time overshoot and ringing Mask No law Rise-time (XS No law Luminance (K rating method) % 3/2 Chrominance (K rating method) % 3/2 3.5.3 Luminance-chrominance inequalities Gain inequality % 2 5 Delay inequality ns 2 5 3.5.4 Steady state characteristics Attenuation/frequency dB 3/2 6 Envelope delay/frequency (xs 3/2 6

(l) Further information on laws of addition is to be found in Doc. CMTT/149 (Canada) and Doc. CMTT/170 (O.I.R.T.), 1966-1969. Note 1. — For circuits on coaxial cables, quadratic addition (A = 2) applies to random noise expressed in terms of r.m.s. voltage. For circuits on radio-relay links, see Recommendation 289-1. Note 2. — Considering the probability of arithmetic addition of power-supply hum in circuits of few sections, it may be advisable to put A = 1 when n < 3. Note 3. — Considering the probability of arithmetic addition when periodic noise consists of a few components that are very close in frequency, it may be advisable to put A = 1 when the number of such components is small. Note 4. — When each of a number of sources of impulsive noise is operative for a small percen tage of the time (e.g. < 0 1 %), arithmetic addition of the percentages will apply. Note 5. — Quadratic addition (A = 2) for gain and delay inequalities is based on the assumption that positive and negative values are made equally likely by the use of correcting networks or equivalent means. Note 6. — In Canada and the United States of America, the practice is to use A = 2. Note 7. — Further information is given in Doc. CMTT/49 (O.I.R.T.), 1966-1969. Rep. 487 — 236 —

REPORT 487 *

TELEVISION REFERENCE CHAINS FOR TERRESTRIAL AND COMMUNICATION-SATELLITE LINKS

(Study Programme 2-1A/CMTT) (1970) 1. As regards the hypothetical reference circuit and reference chains, information available from the Administrations of the United States of America [1] and of the United Kingdom [2] can be summarized as follows: — modification of the existing hypothetical reference circuit to match more closely current and expected future practice in the United States of America does not appear to be necessary for circuits provided by terrestrial facilities, — a long international television connection, including the national extension at each end may be represented by a reference chain consisting of five hypothetical reference circuits. 2. As regards the adequacy of the existing hypothetical reference circuit for circuits including satellite links, the opinions of the same Administrations mentioned in § 1 are as follows: The opinion of the United States of America is that for circuits including satellite links, the existing hypothetical reference circuit is not adequate. The opinion of the United Kingdom is that the transmission performance recommended for a single terrestrial hypothetical reference circuit might also be regarded as a reasonable target performance for a single satellite hypothetical reference circuit from earth station to earth station. Some information on the possible transmission performance to be recommended for a satellite-distribution service was presented by the European Broadcasting Union (E.B.U.) [3]. 3. The large amount of information in the field of picture quality assessments can be found in the papers mentioned in the bibliography of Report 313-2 and in [4] of this Report.

B ibliography 1. C.C.I.R. Doc. CMTT/17 (U.S.A.), 1966-1969. 2. C.C.I.R. Doc. CMTT/21 (United Kingdom), 1966-1969. 3. C.C.I.R. Doc. CMTT/62 (E.B.U.), 1966-1969. 4. C.C.I.R. Doc. CMTT/159 (Italy), 1966-1969.

* This Report was adopted unanimously. — 237 — Rec. 420-2

SECTION CMTT B: MEASUREMENTS, MONITORING, MAINTENANCE

RECOMMENDATIONS AND REPORTS Recommendations

RECOMMENDATION 420-2

INSERTION OF SPECIAL SIGNALS IN THE FIELD-BLANKING INTERVAL OF TELEVISION SIGNALS (MONOCHROME ONLY) (Question 1-1/CMTT and Study Programmes 1-1C/CMTT, 12A/11)

(1963-1966-1970) The C.C.I.R.,

CONSIDERING (a) that, for transmission over international television circuits, it is advantageous to be able to exercise constant supervision of some fundamental parameters of the circuit; (b) that such supervision could be effected by the insertion of special signals in the field-blanking interval; (c) that, for special signals for other uses, which are used in different ways in different countries, international standardization does not seem possible at present, but should take place in the future;

UNANIMOUSLY RECOMMENDS 1. 625-line systems that, for the international transmission of 625-line television signals, the appropriate organi zation should insert the following special signals in the field-blanking interval at the origin of the international transmission circuit as shown in Fig. 1:

1.1 Bar signal — amplitude: white 0-700 V ±0-007 V, — duration: 517/32, — rise and fall times: approximately 1 0 0 ns or alternatively may be derived from the shaping network of the sine-squared pulse.

1.2 Sine-squared pulse

— half amplitude duration: 180 ns ± 2 0 ns, — height: within ± 1 % of the bar amplitude.

1.3 Five-riser staircase signal — height of risers: 0-140 V nominal, — staircase: the difference between the largest and the smallest risers should not exceed 0-5% of the larger amplitude, — peak-to-peak amplitude of the staircase: within ± 1 % of the bar amplitude;

2. that these signals should be inserted in lines 17 and 330. The numbering of the lines is as follows: line 1 is the one starting at the instant indicated by Ov in Fig. 1(a) of Report 308-2. At this instant, the leading edge of the line synchronization pulse coincides with the beginning of the sequence of field synchronization pulses. The lines are numbered according to their sequence in time, so that the first field comprises lines 1 to 312 as well as the first half of line 313, whereas the second field comprises the second half of line 313 and lines 314 to 625;

525-line systems that, for the international transmission of 525-line television signals, line 17 of both fields (lines 17 and 280 if numbered consecutively) be designated as the international insertion test signal lines. The numbering of the lines is as follows: line 1 of field 1 is the line starting with the first equalizing pulse at the instant indicated by Oei in Fig. 3a of Table IIIc of Report 308-2; line 1 of field 2 is the line starting with the second equalizing pulse one half line period after the instant indicated by Oe2 in Fig. 3b of Table IIIc of Report 308-2; Note. — The exact form of the test line waveform to be used is currently under study. that for both 525- and 625-line systems the international signal should neither be removed from nor replaced on the international transmission circuit; that any additional national signals which may have been inserted should be removed prior to the sending of the television signal over an international circuit, if such a removal is requested. Exception is made for the triggering pulse when used by some 625-line system organizations; in this case, such a pulse should be inserted at the beginning of lines 16 and 329 and its duration should not exceed 2 jxs.

Beginning of sync, signal (Oh) White bar Sine-squared pulse Staircase — 239 — Rec. 473

RECOMMENDATION 473

INSERTION OF SPECIAL SIGNALS IN THE FIELD-BLANKING INTERVAL OF A TELEVISION SIGNAL (Study Programmes 1-1C/CMTT and 12A/11) (1970) The C.C.I.R.,

CONSIDERING (a) that it is already current practice in a number of countries to use insertion test signals in the field-blanking interval of a television signal; (b) that such signals can be used for the measurement of performance and the monitoring, control and correction of characteristics of international transmission circuits; (c) that for the international transmission of colour television signals it is necessary to measure a greater number of characteristics than in the case of monochrome television transmission; (d) that Report 314-2 proposes that certain specific lines in each field be allocated for the insertion of special test signals for international transmissions; (e) that future traffic demands may make it necessary to perform all operational measurements by means of insertion test signals, to an accuracy approaching that of conventional out of service measuring methods;

UNANIMOUSLY RECOMMENDS

1 . that for the future international transmission of television signals, insertion test signals in accordance with Annex I (625-line systems) * and Annex II (525-line systems) may be inserted at the origin of the circuit;

2 . that these signals should neither be removed nor replaced on the international circuit, except possibly at a point of conversion of either standard or colour system.

ANNEX I

625-line s y s te m s 1. Introduction For the international transmission of 625-line television signals, Recommendation 472 and Report 314-2 propose the use of lines 17 (330) and 18 (331) for insertion test signals. This Annex describes a comprehensive arrangement of insertion test signals (Fig. 5) to which the following general considerations apply: — it is assumed that the line duration H is divided into 32 equal time periods. This division defines the characteristic instants; — the time periods shall not differ from each other by more than ±40 ns;

* As an interim measure some Administrations may decide to omit some of the waveforms described in this Annex. Where waveforms are omitted: — care must be taken to keep the mean value of the luminance component on the two fields practically constant; — waveforms other than those in Annex I should not be inserted. Rec. 473 — 240 —

— the characteristic instants are referred to the mid-amplitude point of the leading edge of the synchronizing pulse. The luminance and chrominance transitions and the peaks of the pulses occur at characteristic instants; — the actual characteristic instants of any luminance waveform shall not differ by more than 250 ns from their nominal positions; — except in the case of the 207’ pulse, the actual characteristic instants of any chrominance waveform shall not differ by more than 500 ns from their nominal positions; — the colour burst is present in the line-blanking period only in colour transmissions; — in the case of PAL transmissions, the chrominance sub-carrier of the insertion signals is locked at 60° from the (B-Y ) axis. Methods of using some of the test signals described in this Annex are given in Recom mendations 421-2 and 451-1 and in Report 486. The latter document also includes a definition of transmission characteristics.

2. Particulars of signals inserted in line 17 (Fig. 1) 2.1 Luminance bar (reference white level) (B2) — position of transitions: 677/32 and 1177/32, duration of bar 577/32; — bar amplitude: 0-700 ± 0-007 V; — rise and fall times of transitions: derived from the shaping network of the sine-squared pulse or of the staircase waveform; alternatively, may be approximately 1 0 0 ns. 2.2 2T sine-squared pulse (Bf) — peak position: 1377/32; — amplitude: within ± 1 % of the amplitude of the luminance bar (7?a) (nominal value: 0-700 V); — half-amplitude duration: 160 or 2 0 0 ns. 2.3 Composite 20T pulse (F) — position of peak: 1677/32; — position of base: 1577/32 - 1777/32; — amplitude: within ± 1 % of the amplitude of the luminance bar (7?2) (nominal value: 0-700 V); — half-amplitude duration: 2 ± 0-06 jjls; — inherent luminance/chrominance amplitude inequality: ^ 0-5%; — inherent luminance/chrominance delay inequality: ^ 1 0 ns; — perturbations in the pulse base line: ^ 0-5%; — harmonic distortion attenuation of the chrominance sub-carrier: at least 40 dB below the fundamental. 2.4 5-riser luminance staircase (Z^) * — position of successive transitions: 2077/32, 2277/32, 2477/32, 2677/32, 2877/32 and 3177/32 (fall); — peak-to-peak amplitude of the staircase: within ± 1 % of the amplitude of the luminance bar (B2) (nominal value: 0-700 V); — nominal amplitude of risers: 1/5 of amplitude of the luminance bar (2?2) (nominal value 0-140 V). The difference in amplitude between the largest and smallest risers must be less than 0-5% of the largest amplitude;

* Some Administrations may wish to superimpose a chrominance sub-carrier between 1877/32 and 3177/32. — 241 — Rec. 473

— rise and fall times of transitions: deduced from shaping by a Thomson filter (or similar network) with a transfer function modulus having its first zero at 4-43 MHz to restrict the amplitude of components of the luminance signal in the vicinity of the colour sub carrier.

3. Particulars of signals inserted in line 18 (Fig. 2) 3.1 Luminance pedestal — position of transitions: 6/7/32, 31/7/32; — amplitude measured from blanking level: within ± 1 % of one-half of the amplitude of luminance bar (B2) (nominal value: 0-350 V); 3.2 Reference bar signal (Cj) — position of transitions: 6/7/32, 8/7/32, 10/7/32; — amplitudes measured from blanking level: 1st section: within ±1% of four-fifths of the amplitude of the luminance bar (B2) (nominal value:'0-560 V); 2 nd section: within ± 1 % of one-fifth of the amplitude of the luminance bar (Bf) (nominal value: 0-140 V). Reference sinewave signal (C2) This signal may be used as an alternative to the reference bar signal mentioned above: — starting point: 9/7/32; — frequency: 200 kHz; — peak-to-peak amplitude: within ± 1 % of three-fifths of the amplitude of the luminance bar (B2) (nominal value: 0-420 V). 3.3 Sinewave signals superimposed on the pedestal (C3) — starting positions and frequencies of the bursts:

Burst Precise starting Frequency No. position I1) (“) M Hz (3)

1 12/7/32 0-5 2 15/7/32 10-1-5 3 18/7/32 2-0-2-5 4 21/7/32 4-0-4-43 5 24/7/32 4-8 6 27/7/32 5-8

0) The starting point of each burst shall be at zero phase of the sinewave, and each burst shall consist of the maximum number of complete cycles. The gaps between successive bursts shall not be shorter than 0-4 p.s, nor longer than 2 0 (Jts in duration. (2) Some Administrations may prefer to use burst durations different from those shown above and in Fig. 2. (?) The tolerances on frequency and harmonic content must be decided after further study and in accordance with Recom mendation 401-1 and Report 289-1. It is necessary to choose the frequencies of the bursts so that their harmonics do not cause interference to sound sub-carriers on frequencies near 7-5 or 8 MHz on radio-relay systems.

— peak-to-peak amplitude of bursts: within -± 1 % of the amplitude of the reference bar signal (nominal value: 0-420 V); — d.c. component of each burst: not to exceed 0-5% of the amplitude of the reference bar signal. Rec. 473 — 242 —

4. Particulars of signals inserted in line 330 (Fig. 3) 4.1 Luminance bar (reference white level) (B2) — position of transitions: 6/7/32 and 11/7/32, duration of bar 5/7/32; — bar amplitude: 0-700 ± 0-007 V; — rise and fall times of transitions: derived from the shaping network of the sine-squared pulse or of the staircase waveform; alternatively, may be approximately 1 0 0 ns. 4.2 2T sine-squared pulse (Bf) — peak position: 13/7/32; — amplitude: within ±1% of the amplitude of the luminance bar (B2) (nominal value: 0-700 V); — half-amplitude duration: 160 or 2 0 0 ns. 4.3 5-riser luminance staircase (Z>x) — position of successive transitions: 20/7/32, 22/7/32, 24/7/32, 26/7/32, 28/Z732 and 31/7/32 (fall); — peak-to-peak amplitude of the staircase: within ± 1 % of the amplitude of the luminance bar (B2) (nominal value: 0-700 V); — nominal amplitude of risers: 1/5 of amplitude of the luminance bar (i?2) (nominal value: 0-140 V). The difference in amplitude between the largest and smallest risers must be less than 0-5 % of the largest amplitude; — rise and fall times#of transitions: deduced from shaping by a Thomson filter (or similar network) with a transfer function modulus having its first zero at 4-43 MHz to restrict the amplitude of components of the luminance signal in the vicinity of the colour sub carrier. 4.4 Chrominance signal (Z>2) The chrominance signal superimposed on the staircase has the following characteristics: — position and duration: 15/7/32 - 30/7/32*; — peak-to-peak amplitude: 0-280 V ± 2%; — inherent differential-gain distortion: ^ 0-5%; — inherent differential-phase distortion: ^ 0 -2 °; — rise time of the chrominance-envelope transitions: 1 pis approximately; — sub-carrier frequency: 4-43361875 MHz ± 10 Hz.

5. Particulars of signals inserted in line 331 (Fig. 4) 5.1 Luminance pedestal — position of transitions: 6/7/32, 31/7/32; — amplitude measured from blanking level: within ± 1 % of one-half of the amplitude of the luminance bar (B2) (nominal value: 0-350 V); — rise and fall times: as in § 2 .1 . 5.2 Superimposed chrominance bar signal (Gx) — position of transitions: 7/7/32, 14/7/32; — peak-to-peak amplitude: within ± 1 % of the amplitude of the luminance bar (B2) (nominal value: 0-700 Y); — rise and fall times: 1 pis approximately; — inherent chrominance/luminance crosstalk: ^ 0-5% of pedestal amplitude; — phase difference between the sub-carrier superimposed on the staircase in line 330 and the sub-carrier superimposed on line 331 : ^ 2°; — sub-carrier frequency: 4-43361875 MHz ± 10 Hz.

Superimposed sub-carrier may be limited to 2877/32. — 243 — Rec. 473

5.3 Superimposed three-level chrominance signal (G2) This signal may be used as an alternative to the chrominance bar signal defined above: — position of transitions: 777/32, 977/32, 1177/32 and 1477/32; — peak-to-peak amplitudes: 1 st section: within ± 1 % of one-fifth of the amplitude of the luminance bar (7?2) (nominal value: 0140 Y); 2nd section: within ± 1 % of three-fifths of the amplitude of the luminance bar (B2) (nominal value: 0-420 Y); 3rd section: within ±1% of the amplitude of the luminance bar (B2) (nominal value: 0-700 V);

— rise and fall times: 1 p.s approximately; — inherent chrominance/luminance crosstalk: ^ 0-5% of pedestal amplitude; — inherent phase/amplitude distortion: 0 0-5°; — phase difference between the sub-carrier superimposed on the staircase in line 330 and the sub-carrier superimposed on line 331: ^ 2°; — sub-carrier frequency: 4-43361875 MHz ± 10 Hz. 5.4 Superimposed reference sub-carrier (E) This auxiliary signal may be used as a reference sub-carrier for the measurement of differential phase: — position of transitions: 1777/32, 3077/32; — peak-to-peak amplitude: within ± 1 % of three-fifths of the amplitude of the luminance bar (B2) (nominal value: 0-420 V); — rise and fall times: 1 p.s approximately; — phase difference between the sub-carrier superimposed on the staircase in line 330 and the sub-carrier superimposed on the line 331: ^ 2°.

6. List of measurements which can be made with the proposed insertion test signals

Characteristics measured Waveform used Line number

Linear distortions

Insertion gain B z 17 and 330 Amplitude/frequency response C3 and Cx or C2 18 Line-time waveform distortion Bz 17 and 330 Short-time waveform distortion — step response B z 17 and 330 — pulse response B i 17 and 330 ( B2 and Gx or G2 17 and 330, 331 Luminance-chrominance gain inequality < B2 and F 17 I C3 0 and Cx or C2 18 Luminance-chrominance delay inequality F 17

Non-linear distortions

Line-time non-linear D i 17 Chrominance non-linearity G1} G2 and E or F 331, 17 Luminance-chrominance intermodulation — differential gain D z 330 — differential phase D2 and E 330, 331 Chrominance-luminance intermodulation Gi, G2 or F 331,17

(*) Waveforms type C used only if frequency of the burst No. 4 in Ca equals 4-43 MHz.

I Rec. 473 244 —

Line 17

F ig u r e 1 — 245 — Rec. 473

- 1,00

- OjSS

<*44

L 0,30

Line 18

F ig u r e 2 Rec. 473 — 246 —

Line 330

F ig u r e 3 — 247 — Rec. 473

Line 331

Figure 4 e. 473 Rec.

Burst frequencies in MHz

(for details see Figs. 1, 2, 3, 4)

F i g u r e 5 International insertion test-signal Horizontal scale-unit (625-line systems): H/32 — 249 — Rec. 473

ANNEX II

525-line systems

For 525-line television signals, line 17 of both fields (lines 17 and 280 if numbered consecutively) are reserved for international insertion test signals. The exact form of the test signals to be inserted in lines 17 of both fields (lines 17 and 280 if numbered consecutively) is currently under study. Although there are fewer available lines in the field-blanking interval for system M, the space afforded by the two lines will be adequate to accommodate test signals capable of exercising constant supervision of all the basic characteristics of the colour television signal in view of the current state of the art with respect to waveform monitors and special oscilloscopes. Rep. 314-2 — 250 —

CMTT B: Reports

REPORT 314-2 *

INSERTION OF SPECIAL SIGNALS IN THE FIELD-BLANKING INTERVAL OF A TELEVISION SIGNAL (Study Programmes 1-1C/CMTT and 12A/11)

(1966- 1970) 1. Introduction Special signals can be inserted in and removed from the field-blanking interval of a television signal without detriment to the quality of the picture. Such insertion or removal can be done by electronic procedures commonly employed for other purposes in a television system. The purposes of such special signals can be classified in two main categories: — supervision and measurements of various transmission characteristics; — transmission of data concerning operation, such as information, instructions and remote control of equipment. 2. 625-line systems 2.1 The special signals can be placed in two categories, those used for international purposes on the one hand and those used for national purposes on the other. 2.2 At the present time, international special signals are used for the supervision and measure ment of some of the parameters of international circuits. They should be inserted by the appropriate authority at the point of origin of the international circuit and should not be removed or replaced except by the authorities at the terminal point or points of the international circuit (Recommendations 420-2 and 473). 2.3 At the present time, national special signals are used for many purposes including the super vision and measurement of the parameters of transmission circuits, automatic control and correction, and data transmission. National special signals are inserted and removed by the particular authorities concerned. In the case of international transmission, any national signals must be removed if so requested by an authority at the receiving end of the international circuit. 2.4 To facilitate the uses of special signals it is necessary that all countries should accept a field- blanking interval of 25 lines duration (Recommendation 472). 2.5 Although international insertion signals have hitherto been generally regarded as an “in- service” testing method, giving results which are less precise than those obtained by line- repetitive signals, it now seems probable that future traffic demands on the vision circuits could make it difficult to allow time for conventional tests before each programme, and it would in that case be necessary to perform all operational measurements by means of insertion signals. 2.6 During the transmission of colour television signals it is necessary to measure a number of characteristics greater than is possible by means of the signals recommended in Recommen dation 420-2. To achieve this object, it is essential to make two lines available in each field for the international signals, i.e. lines 17 (330) and 18 (331). (For the numbering of lines in the field-blanking interval, see § 2 of Recommendation 420-2. These considerations have led to Recommendation 473.)

* This Report was adopted unanimously. — 251 — Rep. 314-2

2.7 Recommendation 420-2 concerns insertion signals for monochrome television to accommodate those countries wishing to continue to use equipment already available.

2.8 It has been proposed, furthermore [19], to reserve the last line of each field-blanking interval, i.e. lines 22 (335) for the measurement of noise on international circuits.

2.9 Taking the previous considerations into account it is proposed that the diverse types of use be distributed as follows: — data signals: lines 16 (329) — international signals: lines 17 (330) and 18 (331) — national signals: lines 19 (332), 20(333) and 21 (334) — noise: lines 22 (335).

3. 525-line systems

3.1 Special signals are in use with the 525-line systems of Japan [4, 34], Canada [8 , 31] and the United States of America [9, 21, 30]. The current reservation of lines for these signals is as follows:

National transmission Other national International transmission Country testing purposes testing

Japan Both fields: 18 Both fields: 19 Both fields: 17

U.S.A. Both fields: 18, 19 Both fields: 20 Both fields: 17

Both fields: 18, 19 Field one: remainder Field one: first of line 2 0 and last Canada third of line 2 0 third of line 17 Both fields: 17 Field two: last third Field two: line 20 of line 17

The position of the line refers to the beginning of the field-blanking period, as described in Table IIIc of Report 308-2.

3.2 Hie problems involved in the international exchange of programmes for 525-line systems are under study.

3.3 The national signals occupying a portion of line 17 in Canada would be deleted when required for international transmission.

3.4 Transmission of operational information and control signals in line 19, and occasionally other lines, is now fully operational in Japan.

3.5 In the United States of America, current radio regulations allow the radiation by the broad cast transmitter of special signals on only a portion of line 17. Proposals are under consider ation to permit the broadcast of special signals on all of line 17. Rep. 314-2 — 252 —

B ibliography 1. C.C.I.R. Annex 15 to Doc. 11 (France), Geneva, 1963. 2. C.C.I.R. Annex 16 to Doc. 11 (France), Geneva, 1963. 3. C.C.I.R. Doc. 57 (France), Geneva, 1963. 4. C.C.I.R. Doc. 180 (Japan), Geneva, 1963. 5. C.C.I.R. Doc. 211 (O.I.R.T.), Geneva, 1963. 6 . C.C.I.R. Doc. 267 (E.B.U.), Geneva, 1963. 7. C.C.I.R. Doc. 276 (U.S.A.), Geneva, 1963. 8 . C.C.I.R. Doc. XI/4 (Canada), 1963-1966. 9. C.C.I.R. Doc. XI/36 (U.S.A.), 1963-1966. 10. C.C.I.R. Doc. XI/60 (U.S.S.R.), 1963-1966. 11. C.C.I.R. Doc. XI/74 (O.I.R.T.), 1963-1966. 12. C.C.I.R. Doc. XI/89 (Australia), 1963-1966. 13. C.C.I.R. Doc. CMTT/31 (Federal Republic of Germany), 1963-1966. 14. C.C.I.R. Doc. XI/159 (E.B.U.), 1963-1966. 15. Castelli, E. and G iugliarelli, G. II controllo automatico delle reti di distribuzione televisiye (The automatic monitoring of the television distribution networks). Alta Frequenza, Vol. 37, 7, 633-646 (1968). 16. C.C.I.R. Doc. XI/176 (France), 1963-1966. 17. C.C.I.R. Report 411. 18. C.C.I.R. Doc. XI/166 (France and U.S.S.R.), 1963-1966. 19. C.C.I.R. Doc. XI/9 (United Kingdom), 1966-1969. 20. C.C.I.R. Doc. XI/14 (O.I.R.T.), 1966-1969. 21. C.C.I.R. Doc. XI/21 (U.S.A.), 1966-1969. 22. C.C.I.R. Doc. XI/22 (France), 1966-1969. 23. C.C.I.R. Doc. XI/23 (France), 1966-1969. 24. C.C.I.R. Doc. XI/24 (France), 1966-1969. 25. C.C.I.R. Doc. XI/29 (France), 1966-1969. 26. C.C.I.R. Doc. XI/44 (Italy), 1966-1969. 27. C.C.I.R. Doc. XI/52 (E.B.U.), 1966-1969. 28. C.C.I.R. Doc. XI/59 (France), 1966-1969. 29. C.C.I.R. Doc. CMTT/11 (United Kingdom), 1966-1969. 30. C.C.I.R. Doc. CMTT/14 (U.S.A.), 1966-1969. 31. C.C.I.R. Doc. XI/101 (Canada), 1966-1969. 32. C.C.I.T.T. COM IV-No. 175, Part C (Federal Republic of Germany), 1964-1968. 33. C.C.I.R. Doc. CMTT/70 (U.S.S.R.), 1966-1969. 34. C.C.I.R. Doc. CMTT/137, XI/156 (Japan), 1966-1969. 35. C.C.I.R. Doc. CMTT/134, XI/148 (U.S.A.), 1966-1969. — 253 — Rep. 411-1

REPORT 411-1 *

AUTOMATIC REMOTE MONITORING OF THE PERFORMANCE OF TELEVISION CHAINS

(Study Programmes 7A/CMTT and 7B/CMTT)

(1966 - 1970) 1. Introduction ' Due to the development of television chains and the increase of television programme exchanges between countries and different cities, Administrations may wish to employ automatic remote monitoring and control of the qualitative parameters of television chains [1,2, 3,4]. The application of the method of monitoring television chains by means of test-lines makes it possible to check quickly what part of the chain introduces distortions, and to carry out many checks in the course of the transmission. Furthermore, the test-lines enable any distortions arising at various parts of the television chain to be observed on an oscilloscope. Manual control of distortion correcting networks can be based on the observation of the waveforms of the signals on an oscilloscope. For a documentary recording, it is necessary to photograph the screen and to process the photographic material, but in operational use this delay is unacceptable. A new element in this problem is the use of the test-line signals for the automatic documentary recording of the performance of television chains and the transmission of this information for remote monitoring, signalling and automatic control. The use of the test-line method for these purposes is achieved by deriving a low-frequency analogue of the video test signal [1, 5]. It is therefore possible to use low-frequency recording and display devices to obtain automatically the results of measurements; the remote monitoring, signalling and control of the parameters of the chain are carried out by means of a telephone circuit. In addition, by comparing signals with their reference waveform given as an electrical analogue (for example as pulses or slowly changing voltages, etc.), error signals are obtained, which are used for automatic indication of deviations outside the specified tolerances, as well as for the automatic signalling and control of corresponding correctors [1, 4, 5, 7,11,13]. This is particularly important for monitoring the performance of television chains at unat tended stations: The conversion of video test signals into low-frequency signals makes it possible to facilitate routine measurements based on the use of standard monitoring signals. Here, as well as with the use of test-line signals, it is possible to record the measurement results and also supervise the chain at a given point. If the converted signals are returned over a narrow band channel, they may also be displayed at the transmitting end of the chain. Thus, automatic remote monitoring facilitates: — automatic documentary recording of the complete test-signal waveform or its most important characteristic points; — automatic display for a short period of time (“rapid monitoring”) of the deviation from an accepted standard. This information may be used for distortion correction and for the rapid detection of faults in a television chain. In solving these problems in accordance with Study Programmes 7A/CMTT and 7B/CMTT, certain results have already been obtained. At the present time the above problems are being solved in the following ways:

* This Report was adopted unanimously. Rep. 411-1 — 254 —

2. Automatic documentary recording of a test-signal waveform

As the performance of a television chain is normally determined by measuring its waveform response to a prescribed test signal using a suitable mask (as given, for instance, in Recommendation 421-2), the necessity for documentary recording of the signal waveform is obvious. For this purpose the signals on the test-lines at the receiving end can readily be spectrum-converted into a low-frequency signal. For recording this low-frequency signal, chart recorders, magnetic tape recorders, low-frequency oscilloscopes etc. can be used. Almost any form of test signal may therefore be recorded.

Various methods can be used for this conversion. For example, the merit of stroboscopic spectrum-conversion consists in using a relatively simple means to obtain sufficiently accurate reproduction of the special signals inserted into the test-lines. It is also possible to check the waveforms of the synchronizing and blanking pulses, and, if markers are used, the duration of all components of the special signals and synchronizing pulses can be monitored.

The design parameters of such a system are considered in [1, 5], and some experimental results are given in [2, 4, 6 ], where low-frequency control signals were transmitted to the monitoring point over a telephone line using a frequency-modulated carrier.

The time required for conversion, and consequently the duration of the documentary recording of a test signal, is determined by the use intended for this system.

It may be possible to use a different speed of read-out for different kinds of test signals. It may also be feasible to use a spectrum converting arrangement (“rapid monitoring”), in which the waveform is sampled at a small number of points and although the resolution would be reduced the salient features of the test signal may still be determined [5, 6 , 7]. For instance, two speeds of reading out are used in [8 , 9,10] which describe documentary recording of test-signal waveforms. As the rate of change of video signal is very fast in some parts of the test-line and relatively slow in others, it is advantageous to vary the sampling interval and in this system this is achieved by sampling in two stages: firstly over the whole line period and secondly over the shorter period occupied by the sine-squared pulse. The two groups of samples are multiplexed by time division so as to appear sequentially on the display device. Where a telephone channel is used for the telemeter link, it is normal to employ frequency- modulation with the carrier-frequency set at a value determined by the type of line plant.

The preferred characteristics for systems of this‘type are as follows:

Duration of sampling scans 2 jjls and 64 [xs switched alternately Conversion time for each sampling scan...... 1 0 s

Conversion time for a complete test-line...... 2 0 s

3. Rapid monitoring and signalling

The task of rapid monitoring is to find, during a short period of time, the deviations of only the most significant points of the test signals outside the specified tolerances. The signal form corresponding to these tolerances is given by an electrical analogue. Rapid monitoring of the video path can be achieved in two ways. In the first case the same methods and equip ment as described above in § 2 are used, but in a different mode of operation. In each test signal certain significant points in the waveform are chosen and the spectrum conversion is performed using only these points. The information as to the distortion at each point is — 255 — Rep. 411-1

transmitted sequentially over a narrow-band return channel to the transmitting end. The value of distortion is indicated by means of various display devices, printing arrangements and so forth. The signal errors may be recorded and they can also be used for signalling fault conditions and for controlling automatic distortion correctors.

The time during which the information is transmitted depends on the number of signi ficant points to be converted and on the number of fields during which the conversion must be performed [7]. So, if for instance, the recording shows:

black level during 2 fields, white level during 2 fields, synchronizing pulse level during 2 fields, total amplitude of the sine-squared pulse during 5 fields, the first leading overshoot during 5 fields, the first lagging overshoot during 5 fields, the sub-carrier amplitude on the saw-tooth waveform during 1 0 fields,

the whole information will be transmitted during 31 fields (or 0-6 s in a 50-field/second system). In the second case, rapid monitoring and signalling are performed by using threshold devices to indicate those signal parameters which exceed specified limits [11]. A separate threshold detector is used for each parameter. The automatic monitoring device is divided into a waveform distortion measuring unit and a noise measuring unit. There are six parameters covering waveform distortion and the signal-to-noise ratio. The monitoring of waveform distortion includes the following measurements: — amplitude of video signal, — amplitude of synchronizing signal, — 2 T pulse/bar ratio, — streaking on bar, — test-signal amplitude. Measurement of these parameters is performed by time-division for each vertical blanking period, and the measurement is completed in 0 1 s. An alarm signal, “caution” or “trouble”, is issued when predetermined thresholds are exceeded. 4. Method of transmitting the discrete values of test signals

The method of transmitting the discrete values of the test signal [5, 7] allows simpli fication of remote monitoring. In this method any number of test signals are inserted sequentially into the appropriate field-blanking interval.

In measuring the amplitude-frequency response, this method is realized as follows. At the transmitting end of the circuit, in the appropriate field-blanking interval, discrete bursts of sine wave of different frequencies corresponding to the video-frequency band are inserted in turn. The envelope of the overall amplitudes of these bursts, obtained at the receiv ing end as a result of detection, will characterize the amplitpde-frequency response of the video circuit. To obtain the required accuracy, it is necessary for the sine-wave bursts inserted in the consecutive fields to be at frequency intervals of about 250 kHz. Then for a 6 MHz video bandwidth the frequency response as a whole will require the transmission of 24 bursts taking a total time of 0-48 s, for 50-field/second systems. The low-frequency signal characterizing the amplitude-frequency response or its deviations outside the accepted tolerances is transmitted over a narrow-band channel back to the monitoring point. It is feasible to perform the recording of these deviations. It is Rep. 411-1 — 256 —

possible in a similar way, to monitor other characteristics of the video path, for instance, the non-linearity, etc.

5. Automatic monitoring during the transmission of the colour television signals

In the remote monitoring of the fundamental parameters of colour television chains, it may be possible to apply the methods and the arrangements described above in §§ 2, 3 and 4.

For the monitoring of the insertion loss of the luminance signal and of the colour sub carrier, it is possible to transmit a test-line signal, which comprises a white bar, corresponding to Recommendation 421-2 and a burst of colour sub-carrier frequency of the same peak-to- peak amplitude inserted into the unused part of the line [12]. Automatic analysis, recording and remote monitoring of this information is very simple and does not require complex facilities.

It may be required to monitor differential gain and phase in colour television chains and also to correct these distortions [15, 17]. The equipment for recording the differential gain and differential phase, and the gain inequality between the luminance and chrominance signals by means of a special signal inserted in the field-blanking interval, is described in [14]. With this equipment, the recording of indicated characteristics is provided directly during the transmission of the programme. For this purpose the form of this special signal was chosen in such a way, that it was possible to compensate in the equipment the measuring errors due to the noise. This equipment, associated with data processing by means of a suitable programmed computer, was used for an experimental investigation carried out to assess the stability of television radio links [16]. One may consider this system to be promising for the future establishment of a reliable automatic supervision of the whole network. Investigations [18] on the feasibility of automatic monitoring of the quality of a complete television network, consisting of radio links and transmitters, seem to indicate that the essen tial parameters to be monitored during colour television transmissions are: amplitude response, group-delay response, differential gain and phase, non-linearity, signal-to-noise ratio. Essential information on these parameters can be obtained by means of a signal consisting of a three-level staircase, on which sine waves of small amplitude and appropriate frequency are superimposed in time sequence. This type of signal seems to allow a simplification of the measuring equipment.

An experimental installation for continuous automatic monitoring has recently been put into service in Italy. The data supplied in binary form, are sent to a Supervision Centre, where they are processed by a threshold classifier and light a warning signal on a synoptic board. In this prototype installation, the incoming data are also recorded on magnetic tape and then sent to a Data Processing Centre, which, according to a pre-arranged programme provides statistical data on the behaviour of the equipment and the circuits under control. Information is available upon the accuracy of measurement equipment and the influence of noise on the results of the measurements [2 2 ].

6. Television measurement information systems • The use of digital methods [19, 20] for television measurements provides the necessary basis for the optimization of measurement procedures and the transfer and processing of television monitoring/measurement information by digital computers. It is reasonable to combine independent measurement facilities to form comprehensive television measurement information systems. Such systems provide generalized automation by measuring signals which have been specially transmitted and converting the measurement information by logical and mathematical processes in order to facilitate the recording, storage, transmission and read-out of the data in a convenient form. — 257 — Rep. 411-1

The first step in setting up these systems is to introduce digital methods in conjunction with a programmed sequence of measurements and the development of adaptive measurement devices. Data on the characteristics being measured are automatically read out on alphanumeric indicators and indicator lamps in digital or alphabetical form. An important component of television measurement information systems which is used to monitor the performance of a television transmission chain is a computer. Its main functions are to implement optimum procedures for the development and logical processing of measurement information and to read out the results or execute the commands received to insure the satisfactory operation of the television network. In addition to local computers, a central computer unit may be developed, which in addition to carrying out assignments for the television measuring information systems, will have to perform other functions relating to the improvement of national and international television network operation. Basic principles of such systems and the results of experiments are given in [19, 20, 21].

B ibliography

1. K rivosheev, M.I. New principles of design of television chain monitoring systems (in Russian). Teknika kino i televideniya, 10 (1962). 2. O.I.R.T. Doc. TK-III-27 (U.S.S.R.), Bucharest, 1962. Method of automatic remote monitoring and measurement of television chains. O.I.R.T. Technical Commission III. 3. C.C.I.R. Doc. 254 (O.I.R.T), Geneva, 1963. 4. C.C.I.R. Doc. 256 (O.I.R.T.), Geneva, 1963. 5. K rivo sh eev , M.I. Fundamentals of television measurements (in Russian). Moscow, Publishing House Sviaz (1964). 6 . C.C.I.R. Doc. XI/27 (O.I.R.T.), 1963-1966. 7. C.C.I.R. Doc. XI/60 (U.S.S.R.), 1963-1966. 8 . C.C.I.R. Doc. CMTT/54 (United Kingdom), 1963-1966. 9. I n d e p e n d e n t T elevision A u t h o r it y . Interim Technical Memorandum 1/63. 10. I n d e p e n d e n t T elevision A u t h o r it y . A system for remote monitoring of television signal quality by means of a telephone line. Interim Technical Memorandum 8/64. 11. C.C.I.R. Doc. XI/21 (CMTT/8 ) (Japan), 1963-1966. 12. C.C.I.R. Doc. CMTT/31 (Federal Republic of Germany), 1963-1966. 13. C.C.I.R. Doc. XI/4 (CMTT/7) (Canada), 1963-1966. 14. C.C.I.R. Doc. CMTT/35 (Italy), 1963-1966. 15. C astelli, E. On the causes of differential gain and phase on television links. E.B.U. Review, Part A, H.67 (June, 1961). 16. C.C.I.R. Doc. IX/80 (CMTT/23) (Italy), 1963-1966. 17. M a c D ia r m id , I.F. and Sh elley, I.J. Correcting colour signal distortion. Wireless World (March, 1965). 18. C astelli, E. an d G iugliarelli, G. II controllo automatico delle reti di distribuzione televisive (The automatic monitoring of the television distribution networks). Alta Frequenza, Vol. 37, 7, 633-646 (1968). 19. K rivosheev, M.I. Automatic monitoring and measuring in a television chain .(in Russian). Elektrosviaz, 7 (1968). 20. C.C.I.R. Doc. CMTT/69 (U.S.S.R.), 1966-1969. 21. C.C.I.R. Doc. XI/162 (CMTT/143) (U.S.S.R.), 1966-1969. 22. C.C.I.R. Doc. XI/172 (CMTT/152) (Italy), 1966-1969. PAGE INTENTIONALLY LEFT BLANK

PAGE LAISSEE EN BLANC INTENTIONNELLEMENT — 259 — Rep. 412-1

SECTION CMTT C: JOINT TRANSMISSION OF SOUND AND VISION SIGNALS

RECOMMENDATIONS AND REPORTS

Recommendations There are no Recommendations in this section.

Reports

REPORT 412-1 *

TRANSMISSION TIME DIFFERENCES BETWEEN THE SOUND AND VISION COMPONENTS OF A TELEVISION SIGNAL (Question 4-1/CMTT and Study Programme 4-1A-1/CMTT)

(1966 - 1970) 1. Introduction

In the early days of long-distance television transmission, when the video and sound were transmitted via different facilities, there occasionally existed a perceptible lack of simultaneity between sound and vision. Over the intervening years, the networks have been improved. Today, even though the sound and vision of a television programme may be transmitted via different facilities, the transmission velocities used are such that little or no lack of simultaneity between sound and vision is experienced. With the advent of satellite-communication systems, where the sound and vision signals may be transmitted via different media, difficulties may exist at the receiver location because of the lack of synchronization of sound and vision.

2. Conclusions based on observer reaction

Studies of observer reaction to non-simultaneous presentation of pictures and asso ciated sound were reported in Doc. CMTT/1 (Canada), 1965, Doc. CMTT/12 (United States of America), 1965, and Doc. CMTT/55 (Federal Republic of Germany), 1968. General con clusions may be drawn from these experiments.

2.1 Qualitative conclusions The observer is more sensitive to sound advances than to sound delays with respect to the correlated visible action. Observer tolerance to sound/vision time differences varies according to the nature of the action. For example, the objectionable effects of the more easily correlated actions and sounds (such as the percussive sound produced by an object being struck) are detected at considerably shorter time differences than are lip motions of a speaker and the corresponding sounds. For scenes of people moving about, correlation between sound and action becomes more difficult for the observer to detect.

* This Report was adopted unanimously. Rep. 412-1 — 260 —

2.2 Quantitative conclusions

Although the conditions under which the experiments in Canada, the United States of America and the Federal Republic of Germany were conducted differed widely, the results were in broad agreement. In terms of these results, it is possible to derive some provisional figures for overall tolerance to the lack of simultaneity between the sound and the picture.

2.2.1 Sound delayed

For sound delayed with respect to vision, 140 ms will produce, approx imately, a “just perceptible impairment” for 50% of the observers.

2.2.2 Sound advanced

For sound advanced with respect to vision, 70 ms will produce, approx imately, a ‘.‘just perceptible impairment” for 50% of the observers.

2.2.3 The above figures based upon the experiments in Canada and the United States of America are more stringent than necessary in some circumstances, but they allow for some evidence that sensitivity to sound/vision time differences might be greater for some languages than for English in which the first experiments were conducted.

The experiments in the Federal Republic of Germany (Doc. CMTT/55, 1968) have confirmed the above figures using a percussion test which constitutes the most critical case. Moreover, it was found that the tolerances depend very little on the different programme material used. Hence the conclusion may be drawn that the same holds true for other programme material and languages which were not included in the tests.

3. The problem of division of time differences among the links of a built-up connection

The figures cited in § 2.2 must be divided between acoustic links (source to studio microphone, and television receiver to observer) and electrical links. The electrical links may in turn be subdivided between the broadcasting facilities and the telecommunications trans mission networks. Very little information is available on which a practical division may be based.

As an example, in the United States of America, where a variety of programme material is transmitted, it has been found economically feasible on transmission networks to limit sound delay relative to the vision component of a television programme by not more than 50 ms, and sound advance by not more than 25 to 30 ms, at the receiving location. The advance or delay of sound of a television signal that may be introduced because of the difference in transmission velocities on network facilities, can be determined. The advance or delay figures of sound indicated are primarily concerned with the long-distance portion of the network and do not include the inter-city or other contributing sources to the time difference of sound and vision components of the television signal. Other electrical and acoustic links make up the remainder of the sound/vision time difference.

4. Responsibility for making necessary corrections of time differences (Study Programme 4-1 A-l/CMTT

If the sound and vision components of a television signal are transmitted along the same route, and by the same method, there will be no perceptible time difference between the two signals. Where such common routing is not feasible Administrations are urged to provide circuits resulting in time difference values as low as possible. If, in spite of this, considerable time differences should occur, it should normally be the responsibility of the broadcasting authorities concerned to make the necessary corrections. — 261 — Rep. 412-1, 488

This arrangement seems to be most appropriate for the following reasons: — as the two channels only have to coincide at the source and at the destination there is a greater flexibility for routing of channels; — in general, broadcasting authorities will have various possibilities open to them to effect such corrections so that there is no need for the Administrations and/or recognized private operating agencies to provide such equipment.

5. Further work Contributions are invited from various Administrations based on experience and practice with regard to the following: — division of the overall sound/vision time difference among acoustic and electrical links; — methods of controlling sound/vision time differences, arising on the long-distance connection; — new experiments which introduce conditions beyond those previously used.

REPORT 488 *

TRANSMISSION OF SOUND AND VISION SIGNALS BY TIME-DIVISION MULTIPLEX (Question 4-1/CMTT and Study Programme 4-1B/CMTT) (1970) 1. Introduction The transmission of television signals almost always involves the simultaneous trans mission of one or more accompanying sound signals. If required, these signals can be combined as a frequency- or time-division multiplex thus facilitating transmission over a common route. Such an arrangement could be advantageous in those cases where it would otherwise be necessary for the sound and vision circuits to be provided over different routes or facilities which might result in an error of timing between the signals at the receiving end; or where the provision of the required sound circuits by other means was impracticable. The problem of achieving a satisfactory multiplex arrangement between the vision and sound signals will be the subject of further studies ** and this Report summarizes some recent developments which are of interest to C.C.I.R. Study Groups 4, 9, 10 and 11 and to the CMTT.

2. Time-division multiplex of sound and vision signals A television signal requires a wide video bandwidth for satisfactory transmission and this bandwidth is not fully utilized during the synchronizing and blanking periods. Therefore, it would appear to be practical for these periods to be used for the transmission of sound signals without requiring any increase in video bandwidth or making any significant extra demand on the video transmission system. It has been shown that practical systems of modulation which achieve the required standards of performance for the sound channels are feasible.

* This Report was adopted unanimously. ** Frequency-division multiplex systems for the transmission of sound and vision signals are the subject of Question 3-1/9 and Question 18-1A/10. Information on the systems is contained in Recommendation 402 and Reports 289-1 and 403-1. Rep. 488 — 262 —

Doc. CMTT/15 (United States of America), 1966-1969, describes a time diplexed system for the 525-line system M in which the audio signal is transmitted as an amplitude- modulated pulse situated in the front-porch of the video line-blanking signal. The derived sound channel is equivalent in bandwidth, signal-to-noise ratio and other significant trans mission characteristics to the 5 kHz sound channels provided by conventional means and commonly used for long-distance television sound transmission. Doc. CMTT/25 (United Kingdom), 1966-1969, gives the theoretical and practical considerations of an experimental time-division multiplex arrangement for a 625-line system. The audio signal is sampled at twice line-frequency and information is stored and coded into two groups of binary-coded pulses which, together with an additional marker pulse, are transmitted during the line-synchronizing pulse period. A high quality music channel having an upper frequency of about 14 kHz can be obtained. More recent information on this system is now available [5, 7]. Doc. CMTT/60 (France), 1966-1969, describes an experimental pulse-width modulation system for the 625-line system L. The audio signal modulates the position of the trailing edge of a burst of chrominance sub-carrier situated in the back-porch of the video line-blanking signal. A medium quality sound channel may be derived in this manner. The U.S.S.R. have made various studies of time-division multiplex systems for the simultaneous transmission of sound and vision signals [8-12], In the MOLNIYA and ORBITA satellite systems of the U.S.S.R., sound signals are transmitted as a position modulation of pulses on the back-porch of the video line-blanking signal. Doc. CMTT/144 (U.S.S.R.), 1966-1969, describes two time-division multiplex systems for use with the SECAM colour system. Table I summarizes the information on the various systems described in the docu mentation. It should be noted that each system provides one sound programme channel.

\ — 263 — Rep. 488

T a b l e I

C.C.I.R. Doc. CMTT/25 CM TT/15 X I/134 CMTT/60 CM TT/144 (U.S.S.R.) Period (U.S.A.) (France) 1966-1969 (U.K.)

525 line 625 line 625 line 625 line Video system (NTSC) (PAL) (SECAM) (SECAM) Audio Pulse- Pulse-code Pulse-width Pulse-width modulation modulation amplitude modulation modulation of system modulation sub-carrier burst Video waveform None Increased Sub-carrier (a) Increased (a) Increased modification duration of bursts on deviation deviation line-frequency pedestal con line-blanking line-blanking equalizing tinued through (b) Line sync, (b) Line sync, pulses field-blanking pulse: pulse: displaced in displaced in time and its time and its duration duration decreased decreased (c) Decreased duration of front porch Audio bandwidth 5 14 6 6 10-14 (kHz)

Audio When used with 68 40 60 53 signal-to- a compandor (with (without (video S/N = (with weighted the signal-to- compandor) compandor) 41 dB) compandor) noise ratio noise ratio is (video S/N == (dB) equivalent to 55 dB) that of a conventional 5 kHz circuit Audio S/N dependent Yes Yes upon Yes No Yes video S/N Rep. 488 — 264 —

B ibliography 1. C.C.I.R. Doc. CMTT/15 (U.S.A.), 1966-1969. 2. C.C.I.R. Doc. CMTT/25 (United Kingdom), 1966-1969. 3. C.C.I.R. Doc. CMTT/60 (France), 1966-1969. 4. C.C.I.R. Doc. CMTT/144 (U.S.S.R.), 1966-1969. 5. C.C.I.R. Doc. CMTT/156 (E.B.U.), 1966-1969.

6 . C.C.I.R. Doc. XI/134 (United Kingdom), 1966-1969.

7. S h o r te r , D.E.L. The distribution of television sound by p.c.m. signals incorporated in the video waveform. E.B.U. Review, Part A, 113,13-1& (February, 1969). 8 . T a l y z in , N.V., K a n t o r , L.Y. and T seitlin , M.Z. Orbita earth station for receiving television programmes from artificial earth satellites (in Russian). Elektrosviaz, 11 (1967). 9. S e v a l n e v , L.A. and T sir l in , Y.M. Transmission of the sound component over satellite commu nication circuits (in Russian). Vestnik sviazi, 1 (1969. 10. K a t a e v , S.I. and Z u b a r e v , Y.B. Transmission of picture and sound components in combined frequency band (in Russian). Tekhnika kino i televideniya, 7 (1965). 11. Y a sc h e n k o , K.A. and Z verev, Y.B. Transmission of televisioii sound component by time division multiplexing of the video signal by phase modulated pulses (in Russian). Elektrosviaz, 8 (1964). 12. E sin , V.T., T o v b in , M.N. a n d S k l iz k o v , V.M. A method for the transmission of the picture and sound signals on the same channel in colour television (in Russian). Tekhnikdkino i televideniya, 6 (1968). — 265 — Rec. 474

SECTION CMTT D: SOUND PROGRAMME TRANSMISSION

RECOMMENDATIONS AND REPORTS Recommendations

RECOMMENDATION 474

MODULATION OF SIGNALS CARRIED BY SOUND PROGRAMME CIRCUITS BY INTERFERING SIGNALS FROM POWER SUPPLY SOURCES

The C.C.I.R. (1970)

UNANIMOUSLY RECOMMENDS that the most intense unwanted side component due to modulation of a sound programme signal caused by interfering signals from power supply sources should not be of greater level than —45 dB relative to the level of a sine-wave test signal applied to the sound programme circuit.

Note 1. — This limit is identical to that which is considered tolerable for other types of transmission (FM and AM-VF telegraphy, facsimile transmission, speech, telephone signalling and data transmission). Note 2. — This limit applies only where the interfering signals are the usual low order mains frequency harmonics. For modulation by much higher frequencies a more stringent limit is likely to apply; this would require further study. Note 3. — For design purposes this limit should be taken as applying to the hypothetical reference circuit of length 2500 km. Note 4. — See also Report 495. Rep. 489 — 266 —

CMTT D: Reports

REPORT 489 *

CIRCUITS FOR HIGH QUALITY MONOPHONIC PROGRAMME TRANSMISSIONS (Study Programme 5-1A-1/CMTT) (1970)

The first part of the Study Programme asks whether a study should be made of recom mendations for circuits of higher quality than those of Type A (C.C.I.T.T. Recommendation J.21). Doc. CMTT/28 (L. M. Ericsson) points out that the deletion, in 1954, of the Recom mendation contained in the Annex to this Study Programme was due to the very small demand for such circuits. It then states that information assembled by C.C.I.T.T. Study Group IV (Contribution COM IV - No. 175, page 61) shows that most requests are for less expensive circuits of reduced quality. This view is supported by the experience of the United States of America and Canada which is that practically the only demand for high quality circuits is for short links between studios and transmitters. For longer distances the cost is very high and in consequence the demand is limited. The E.B.U., on behalf of many countries, has expressed a view in Doc. CMTT/136 on the classification of programme circuits including the need for high quality circuits of 15 kHz bandwidth over long distances within Europe; there is thus a demand for high quality mono phonic circuits of up to 2500 km length and studies should be made of suitable recommendations. The second part of the study asks what the general characteristics of such circuits should be. It is agreed that the specification of a high quality monophonic programme circuit should be identical to that of one circuit of a stereophonic pair intended for the transmission of signals A and B and to that for a channel to carry the M signal. Some special parameters relat ing specifically to the stereophonic aspect can be omitted from the monophonic specification. The recommendation for a high quality monophonic programme circuit will be prepared after that for stereophonic programme transmission covered by Study Programme 5-1B-1/CMTT has been agreed. Study Programmes 5-1A-1/CMTT and 5-1B-1/CMTT will therefore be considered jointly and due account will have to be taken if the tolerances on any parameters are different for monophonic transmission and stereophonic transmission.

* This Report was adopted unanimously — 267 — Rep. 490, 491

REPORT 490 *

CHARACTERISTICS OF CIRCUITS CURRENTLY OFFERED FOR TRANSMISSION OF SOUND PROGRAMME SIGNALS OVER LONG DISTANCES (Question 5-1/CMTT) (1970) Among the aims of Question 5-1/CMTT is a study of the parameters and their values and tolerances of sound programme circuits. Docs. CMTT/16 (United States of America) and CMTT/127 (United Kingdom), 1966-1969, give pertinent data as to sound programme circuits offered in the United States of America and in the United Kingdom, respectively. In addition, Doc. CMTT/136 (E.B.U.), 1966-1969, gives the views of the European Broadcasting Union as to the classes of programme circuits required for international service. It would be desirable for all interested Administrations to submit comparable inform ation on their current practices for the provision of circuits of all bandwidths for use in the preparation of a comprehensive report on that portion of Question 5-1/CMTT.

REPORT 491 *

CHARACTERISTICS OF SIGNALS SENT OVER SOUND PROGRAMME CIRCUITS (Study Programme 5-1D-1/CMTT) (1970) 1. Characteristics of test signals The first point of the Study Programme 5-1D-1/CMTT is concerned with the charac teristics of the test signals used by broadcasting authorities on sound-programme circuits and asks if new types of test signals are to be expected. Some Administrations note that new types of test signals are to be expected. Reference [1] also suggests that new test signals may be wanted, in particular for non- linearity tests and for stereophonic circuits. It also points out that, as a guiding principle, no test signal should place more stringent demands on the transmission path than actual traffic. A new test signal for crosstalk and non-linearity tests is proposed for study in Report 497. The broadcasting authorities are invited to give for the next meeting of CMTT detailed information for this point of the Study Programme.

2. Mean power of programme signals The second point of the Study Programme 5-1D-1/CMTT is concerned with the mean power of programme signals presented to transmission circuits and with the distribution of

* This Report was adopted unanimously. Rep. 491 — 268 —

the quasi-instantaneous power, but it seems likely that the distribution of, for instance, the one-minute mean power will also be needed.

2.1 General

Reference [2] gives a warning that programme signals presented for transmission have frequently been submitted to selected and adjustable emphasis in the studio to meet artistic requirements. In consequence of this it may be unwise to draw broad conclusions about the power spectrum of programme signals because the power levels at higher spectrum frequencies may for instance have been increased substantially above the “normal” value. An increase of this nature may tend to invalidate the basis on which the C.C.I.T.T. Programme Pre-emphasis Network was chosen (see C.C.I.T.T. Blue Book, Vol. Ill, 1965, pages 547-548). The network is used at the input to a carrier programme transmission channel. “Studio Emphasis” must be accepted as a fact and the various tests must include a realistic proportion of such material. This type of programme material is particularly necessary when measuring the statistical distribution of programme power in various parts of the spectrum. It is noted that Report 497 proposes that a shaped band of noise should be used as a test signal to simulate a sound programme. The study of spectral power distribution of real sound programmes will be of value when assessing the new test signal.

2.2 Signal level at the zero relative level point

It is understood that at the zero level point, the quasi-peak level of the programme signal will be 9 dBm, but that the instrument used for setting the level has not been widely standardized. It is essential that information must always be made available on the type of unit used for any series of measurements and also on the mode of using it. It is further desirable that information should be made available on the instantaneous peak levels measured at the zero points of the programme circuits. This information is of interest in connection with transmission channels as well as with transmitters. It is most readily measured on an oscilloscope. (The equivalent sine-wave power of the peak is 0-5 V2/Z 0 where V is the peak voltage.)

2.3 Mean power levels

2.3.1 For many purposes the mean power level, taken for instance over one-minute intervals, is very significant. Reference [3] gives such information in the form of the distribution over the day for two classes of programmes: programme No. 1 with a preponderance (up to 60—65 %) of speech and programme No. 2 with a preponderance (up to 35 —40 %) of jazz and symphony music. Table I is taken from this document. Analysis of the measurements carried out showed that the lower the mean power of the excerpt, the more the dynamic range compressor increases the mean power. In the excerpts investigated, the difference between the level of the one-minute mean power with the compressor switched in and with it switched out, varied within the limits of 2 dB and 17 dB. The transmission power with the pre-emphasis network switched in depends on the spectral density of the signal. In the excerpts studied, the difference between the levels of the one-minute mean power with the pre-emphasis network switched in and with it switched out, varied within ±7 dB. — 269 — Rep. 491

T a b l e I

Power of the broadcasting signal at a point of zero relative level of the sound programme circuit (dBmO)

Averaging periods and levels With compandor Without compandor followed or pre-emphasis by pre-emphasis

Programme Programme Programme Programme No. 1 No. 2 No. 1 No. 2

Day (level of long-term mean power) -5 -7 -4 -5 -0 -6 +0-5 Hour (most highly-probable level of mean power) -4 -6 -3-1 +0-7 + 1-4 Level of one-minute mean power exceeded during 20 % of the day -4 -4 -2 -5 +0-7 +2-2 Level of one-minute mean power exceeded during 1 % of the day - 1 - 0 1 +3-6 +4-1 Level of one-minute mean power exceeded during 01 % of the day + 1-7 +2-2 +4-3 +4-9

Note 1. — When the signal, after compression and pre-emphasis, is applied to a carrier line, an attenuation of 1-7 dB is used in transferring the programme circuit zero level point to the carrier circuit zero level point. Note 2. — The compandor has a compression coefficient of 2 and an unaffected level of + 9 dBm. Note 3. — The pre-emphasis network complies with C.C.I.T.T. Recommendation J.21. Note 4. — While the measurements were taken there were no signal limiters in circuit (manual control).

2.3.2 Table II gives some power loading figures obtained from [4].

T a b l e II

Signal Long term (week) Maximum value of mean power 1 s mean power (dBm) (dBm)

Studio output f1) -4 -8 + 4

With pre-emphasis (2) -2 -9 + 9

With carrier compandor (3) -0 -3 + 4

With pre-emphasis and new compandor (4) - 6

C1) Measured at the zero relative level point of the sound programme circuit. (2) The pre-emphasis circuit has a loss of 1-5 dB at 800 Hz and its output is applied to the zero point of a telephone circuit. (8) The compandor has an unaffected level of + 5 dBmO and is described in NTZ Communications Journal, 2, pp. 66-72 (1962). The levels quoted are referred to the zero relative level point of a telephone channel. (*) The compandor is described in Siemens-Zeitschrift, Vol. 43, pp. 598-603 (July, 1969). The levels quoted are referred to the zero relative level point of a telephone channel. Rep. 491 — 270 —

2.3.3 Table III is derived from [5].

T a b l e III

Signal at the Long-term (few hours) mean power Studio output compandor output signal (2) (9 (2) (3)

On average -1 -7 dBmO -2 -2 dBm Exceeded 10% +2*6 dBmO +2-6 dBm Exceeded 1 % + 8-7 dBmO +7-8 dBm

C) The compandor has an unaffected level of +5 dBmO and is desoribed in reference (a) appended to Table II above. (2) Pre-emphasis is not employed. (s) The power is measured at a point where the output is 0 dBm when the input to the compandor is 0 dBmO.

2.3.4 From [6 ], a mean distribution for a sound programme not subjected to any process of limitation or compression is quoted. The median power level is -9-2 dBmO and the standard deviation is 1-7 dB. Distributions of processed sound programmes are also included. Table IV is an extract from that document.

T a b l e IV

Partially limited Entirely limited and compressed and compressed Probability of exceeding Studio output (dBmO) signal signal (dBmO) (dBmO)

Long-term mean -8 -9 -6 -4 -2 -4 20% -7 -8 - 5 0 -1 -7 1% - 5 0 -2 -2 0

Note. — Meaning of “limited” and “compressed” is contained in [6 ].

2.4 Peak power

2.4.1 From [3], if a quasi peak power level of +9 dBmO (as measured by an instrument with an integration time of 2 0 ms) is not exceeded at the studio output, then the quasi peak power measured at the input of a carrier programme circuit exceeds a value of + 12 dBmO for 8 % of the time for programme No. 1 and 17% of the time for pro gramme No. 2. A compandor followed by a pre-emphasis network and 1-7 dB atte nuation is connected between the studio output and the carrier equipment.

The analysis was made of excerpts of a programme transmission of varied composition, lasting 5 to 30 minutes, pre-recorded on magnetic tape. These excerpts were divided into one-minute sections and for each section the distribution of the instan taneous voltage values was deduced by means of a 10-channel analyser. The measure ments obtained were used to determine the dispersion which, on condition that the arithmetic mean of the instantaneous voltage values is equal to zero, is proportional to the one-minute mean power of the signal.

2.4.2 From [4], the peak power will exceed +15 dBmO with a probability of 10~5. — 271 — Rep. 491

2.4.3 From [6] the following is obtained:

Instantaneous peak Probability power of studio of exceeding output signal

1(H + 10 dBmO 1(H + 12-5 dBmO io-5 + 14-3 dBmO

2.4.4 From [5], it is permissible to conclude that +10 dBmO on the programme circuit is rarely exceeded.

2.5 Spectral power distribution 2.5.1 Reference [3] gives some spectral power distributions. Figs. 1, 2, 3 and 4 are reproduced from this source. The spectral characteristics of the one-minute mean powers of the broadcasting signals were measured over the same one-minute programme excerpts. The measurements were made with equipment incorporating 1/3 octave filters and a voltmeter with a square law detection characteristic. The spectral characteristics were determined for 100 one-minute excerpts of different kinds of broadcasting programmes. The characteristics obtained were classified into 17 groups (according to the nature of the transmission) and the average spectral characteristics were determined for each group. Figs. 1 and 2 give two distributions as an example: one for male speech and one for a symphony orchestra. Analysis of the characteristics showed that, for all types of programmes, most of the power is concen trated in the comparatively narrow band of 50 — 1200 Flz. The vertical scales on the four figures are not intended to indicate absolute values but give relative spectral power density per unit bandwidth. Measurements of the spectral characteristics of broadcasting signals in the channel with the compressor switched in showed that the compressor does not alter the spectral character of the signal.

2.5.2 Figs. 5 and 6 of [6 ] show the spectral average power distribution for five different programme items recorded on magnetic tape. Measurements were effected by means of a square-law instrument connected to a recorder able to record a signal variation speed of 250 dB/s. The writing arm of the recorder was connected to a level analyser having 5 dB spaced thresholds, a sampling duration of 2 0 jjls and a sampling rate of 1 0 per second. The frequency analysis of the programme items was carried out on contiguous third octave bands from 31 to 16 000 Hz (constant relative bandwidth analysis). For each third octave band the statistical distribution of the instantaneous power of the different items has been recorded and afterwards the distribution of the mean value of the power has been calculated.

Figs. 5 and 6 are in terms of power per Hz (dBm/Hz).

2.5.3 Reference [4] states that the spectral power decreases at a rate of 3 dB per octave during those parts of the sound programmes which are of high power level when the analysis covers a one second period, but by 6 dB per octave for long-term observations. Rep. 491 — 272 —

2.6 Observations

2.6.1 There appears to be agreement between some of the mean level power measurements but not all. (The long-term mean power ranges from —8-9 dBmO to —1-7 dBmO). The distribution of one-minute mean power is probably of greater interest than the long-term mean power as the former places a more stringent requirement on the design of transmission systems. The distribution of one-minute mean power (dBm) could be expressed either as a median and a standard deviation or as a power level which will not be exceeded for more than a small percentage of the time (20% and 1%). If the assumption that the distribution of one-minute mean power levels (dBm) is Gaussian is valid, then the one expression can be derived from the other. The differences in the available data do not permit a single set of figures to be chosen at present.

2.6.2 The instantaneous power level, which is exceeded with a probability of 10-5 is of particular interest because multi-channel carrier systems are designed on that basis. It is desirable to fix more precisely the time interval over which an instantaneous power should be averaged (over a few milliseconds). The data so far considered have not generally quoted the instantaneous power in this way but the indications are that a figure of +15 dBmO is unlikely to be exceeded for a probability of 1 0 -5.

2.6.3 It is difficult to draw firm conclusions from the spectral analysis primarily because typical programme material is so variable in content. National characteristics might also have a bearing on spectral power distribution. However, on the basis of measure ments so far, it can be concluded that, even for programmes of the widest spectrum (symphony orchestra), the basic power of the signal is concentrated in the band 50-1200 Hz.

3. Proposal for the form of future measurements

3.1 A statement is required about the control of the “studio output”. The general aim is that the quasi-peak level should not exceed + 9 dBm at a zero relative level point of the sound programme circuit. The method of control used should be stated and the important features of any equipment used should be described. 3.2 Measurements should be expressed as relative to the zero relative level point of the sound programme circuit. For the analysis of the “studio output”, it is convenient to work in terms of one-minute samples. For a particular example of a broadcast programme samples might be taken for each minute or possibly alternate minutes. The results of tests should be presented in a form which shows the values exceeded for 2 0 %, 1 % and 0 1 % of the time for the mean power results and 1 0 -3, Iff-4 and 10~ 5 of the time for instantaneous peak values.. 3.3 From each sample the following data should be determined. 3.3.1 Mean power (one-minute mean). 3.3.2 Instantaneous peak power in terms of equivalent sine wave (V2j2Z). 3.3.3 For each one-minute sample determine the ratio of the instantaneous peak to mean power. 3.4 Spectral information is also desirable and is conveniently determined also from the one- minute samples. From each sample the following should be obtained using 1/3 octave filters according to IEC Publication 225: — 273 — Rep. 491

3.4.1 Mean power (one-minute mean) corrected for filter shape; 3.4.2 Instantaneous peak power in terms of the equivalent sine-wave power; 3.4.3 To reduce the amount of detail spectral analysis, measurements need only be made for individual spectral channels when the result is likely to contribute to the upper 2 0 % of the distribution for the particular 1/3 octave channel; 3.4.4 Data obtained from these measurements will be of value when determining the charac teristics to be used for the test signal in Report 497.

4. Characteristics of monitoring and signalling tones The fifth point in the Study Programme 5-1D-1/CMTT is concerned with the charac teristics of monitoring and signalling tones used by the broadcasting authorities. Reference [7] contains information on signals which are either being used or under consideration for these purposes in the United Kingdom. The monitoring signals are sent over sound programme connections to provide an indication as to whether or not the connections are transmitting the programme signals effectively. They may consist of unmodulated tones, either single or combined or a single tone sub-carrier, modulated in amplitude or frequency by a processed monitoring signal having a limited frequency range. As processing of the programme signal consists essentially in the extraction of minimal information relevant to monitoring, the frequency and amplitude ranges of the processed signal are much less than those of the programme signal. It is therefore feasible to transmit the processed signal by a carrier of suitable frequency at the top end of the frequency spec trum of the programme transmission link. A bandwidth of about 400 Hz is all that is necessary for this purpose and if the monitoring information is conveyed by frequency keying or by frequency modulation, then carrier amplitude variations are relatively unimportant. With frequency keying a selection of one or a combination of two tones of frequencies just above the nominal upper frequency of the link is used (e.g. 10-6 kHz and 10-8 kHz on a nominal 10 kHz link). The signals are transmitted over the link at a level of about —33 dBmO, filtered from the programme signal at the distant end, and used to re-constitute digital signals. Comparable digital signals are also processed from the programme signal at the output of the link and the two sets of digital signals are compared. In the frequency-modulation system which is under consideration the monitoring signal processed from the input programme signal is transmitted over the programme channel by a frequency-modulated carrier having a centre frequency just above the nominal upper fre quency of the channel (e.g. 10-7 kHz on a 10 kHz channel). The carrier level will be about —30 dBmO and the deviation such that the signal bandwidth is about 400 Hz. A discriminator at the far end regenerates the equivalent input processed signal which is then compared with a monitoring signal processed from the output of the link.

Bibliography 1. C.C.I.R. Doc. CMTT/31 (L.M. Ericsson), 1966-1969. 2. C.C.I.R. Doc. CMTT/22 (United Kingdom), 1966-1969. 3. C.C.I.R. Doc. CMTT/153 (U.S.S.R.), 1966-1969. 4. C.C.I.T.T. Annex to Study Programme 5D/CMTT in Addendum 3 to the C.C.I.R. Documents of the Xlth Plenary Assembly, Oslo 1966, Vol. V, 382 h. 5. C.C.I.R. Doc. CMTT/121 (Switzerland), 1966-1969. 6 . C.C.I.R. Doc. CMTT/158 (Italy), 1966-1969. 7. C.C.I.R. Doc. CMTT/130 (United Kingdom), 1966-1969. Rep. 491 Rep. Level of transmission (Np) • — malespeech — Averaged spectralcharacteristic level f of transmission o maleof speech Frequency,Hz 24 — 274 — F igure 1 Level of transmission (Np) 5

0 0 0 0 20 0 10 20 50 10000; 5000 2000 1000 500 200 100 50 20 10 ------Averaged spectral characteristic f level f transmissiono o symphonya of orchestra symphonyorchestra

11111 ------Frequency, Hz Frequency, F igure

275 2 -1 LJ 1- 1------

iJ- M -C -i-J L Rep. 491 Rep. Rep. 491 Rep. Level of transmission (Np) - • Programme No. 2 No. Programme • - a 0 0 0 0 20 0 10 20 50 10000 5000 2000 1000 500 200 100 50 20 10 Averaged spectral characteristics f level o transmission of f dailybroadcastingo programme ■■ 1No. Programme taking account f theincidence o f transmissionso withdifferent characteristics Frequency,Hz 26 — 276 — F igure 3 , Level of transmission (Np) * withpre-emphasis circuitswitched off • __ withpre-emphasis circuitswitched on o Averaged spectralcharacteristic f leveltransmissiono of lightaof orchestra withthe pre-emphasiscircuit switched off and withswitchedit on — F Frequency,Hz igure l l I Rp 491 Rep. — 4

Rep. 491 Rep. dBm/Hz Curve A: classicalCurveA: music Meanspectral powersoundof signals rqec, Hz Frequency, Curve B: opera CurveB: 28 — 278 — F igure 5 Curve C: modern music modern CurveC: dBm/Hz Meanspectral powersoundof signals uv : speech Curve E: Curve D: jazz CurveD: rqec, Hz Frequency, 29 — 279 — F e r u g i 6

Rep. 491 Rep. Rep. 492 — 280 —

REPORT 492 *

REVISION OF C.C.I.T.T. RECOMMENDATION J.21 (Study Programme 5-1C-1/CMTT) (1970)

1. In Study Programme 5-1C-1/CMTT, the C.C.I.T.T. has invited the CMTT to say whether it considers that the Recommendation for type A programme circuits should be amplified. Docs. CMTT/23 (United Kingdom) and CMTT/30 (L. M. Ericsson) have been received in response to this question. 2. Doc. CMTT/23 suggests that there is a need for a reference chain spanning distances of more than 2500 km and that the reference chain for sound programme circuits should be comparable to that for television circuits. The reference chain for television circuits is being studied under Question 2-1/CMTT. The principle of comparability between the television and sound reference chains is agreed but discussion of the reference chain for sound programme circuits has been deferred until after the reference chain for television circuits has been agreed. The study of television reference chains is covered by Study Programme 2-1A/CMTT. 3. Doc. CMTT/30 suggests that the following additional points should be included in Recommendation J.21: — error in reconstituted frequency; — hum modulation; — impulsive noise; — single tone interference. The first point is referred to in the note to the question and has been, studied in the CMTT, as mentioned below. The second is covered by Recommendation 474. The third has been studied by C.I.S.P.R. whose results are contained in their Publication No. 1. On the fourth point the subjective assessment of single tone interference on high quality circuits will be done by a method described in Report 496. Some of the results may be applicable in a reconsideration of Recommendation J.21.

4. Maximum frequency error tolerable from the point of view of the transmission quality of a type A programme circuit 4.1 Introduction A maximum error of 2 Hz between the initial and reconstituted frequencies was recom mended by the C.C.I.T.T. for carrier telephone circuits from the point of view of voice- frequency telegraphy (Recommendation G.225). If the individual oscillators conform to this Recommendation, experience Shows that this value is hardly ever exceeded on a telephone channel having a composition the same as the 2500 km reference circuit. It is to be expected that this would also apply in the case of a programme circuit having the same composition as the 2500 km reference circuit and assuming that the virtual carrier frequencies of the programme modulating equipment conform to the accuracies specified for virtual channel carrier frequencies in a group. However, it had not been established at the time whether this limit was acceptable or whether it should be reduced from the point of view of the frequency shift that can be tolerated in a programme channel transmitted on a carrier circuit. Information on this limit is particularly useful even considering that modulation equip ment for programme circuits often embodies its own carrier generators which are not frequency locked to the master oscillators of the telephone system.

* This Report was adopted unanimously. — 281 — Rep. 492

4.2 Contributions received Information on this subject has been sent by L. M. Ericsson (Doc. CMTT/28, § 2.9), Italy (Doc. CMTT/6 6 ) and the B.B.C. (Doc. CMTT/74). In the L. M. Ericsson contribution, very stringent requirements are suggested, involving a precision in frequency reconstitution of the order of 01 Hz, in so far as this problem is considered by them to be very similar to the problem of tuning musical instruments. On the other hand, in the Italian contribution and in the B.B.C. contribution, the results of subjective tests are reported. The tests described in the Italian contribution were carried out along three different lines:

4.2.1 subjective determinations based on opinion tests for music and speech programmes impaired by errors on the reconstituted frequencies;

4.2.2 subjective determination of the perception threshold for the frequency-shift by direct comparison between the unaltered circuit and the circuit with a given amount of frequency shift;

4.2.3 subjective determination of the perception threshold for the frequency shift for simple musical signals obtained by synthesis or played on the piano and on the organ. In the tests under §§ 4.2.1 and 4.2.2 a degree of harmonic distortion was introduced to check interaction between the two types of disturbance. The contribution concludes that impairment due to an error of 2 Hz is detected only by musicians and even then with some difficulty, but it is noted that for certain types of musical signals the minimum spectrum shift noticeable is distinctly below 2 Hz. The B.B.C. contribution reports the mean score, on an impairment scale obtained from many observers who listened to some short musical excerpts, shifted in frequency and pre viously selected as the more significant ones to the purpose of the tests. As a conclusion this Report suggests that the permitted tolerance should not exceed the present figure of 2 Hz, no evidence being at present available to justify any tightening of it.

4.3 Conclusions Concerning Study Programme 5-1 C-l/CMTT, the CMTT suggests that the maximum difference of 2 Hz between the initial and reconstituted frequencies, established for inter national telephone circuits, will also ensure satisfactory quality on type A programme circuits as now defined. Some Administrations, however, point out that the minimum spectrum shift noticeable is distinctly below 2 Hz and this fact will have to be taken into consideration in studying the definition of the characteristics of higher quality programme circuits for future use.

5. Noise weighting network

The CMTT considers that the new weighting network which will be used for high quality sound programme circuits will be suitable for circuits of 10 kHz bandwidth (conforming to Recommendation J.21) and may also be not unsuitable for smaller bandwidth circuits. While it is the intention of the CMTT to include the new weighting network in Recom mendation J.21 at a later date, this will require further study in respect of, amongst other things, the noise conversion factor, and Administrations are invited to confirm by practical tests the values suggested in Report 496. Rep. 492, 493 — 282 —

6. Comments on reply of Special Joint Study Group C to Question 10/C 6.1 Special Joint Study Group C (C.C.I.T.T./C.C.I.R.) has been making a study, under its Ques tion 10/C, of the permissible noise on sound programme circuits carried on radio-relay links with the objective of amending C.C.I.T.T. Recommendation J.21 to take account of the different nature of the noise on radio-relay links. The Question makes a distinction between circuits set up on radio-relay links intended for television and circuits set up on a sub-carrier of a radio-relay link for television. C.C.I.T.T. Document AP IV/51 (COM Sp. C - No. 69) contains the reply to this Question. The substance of this reply is found in C.C.I.R. Report 375. 6.2 Report 375, § 3.2, points out that a definition is needed of the conventional loading of a tele vision channel, in order that the conditions of measurement for programme circuit noise can be stated. The CMTT considers that it should study this problem under the new Question 8 /CMTT. 6.3 Report 375, § 3.2, raises the issue of interference to the programme channels from test signals sent over the television channel. The CMTT is already studying the limits for various forms of interference under Study Programmes 5-1 A-l/CMTT and 5-1B-1/CMTT and will include this form of interference in its study. 6.4 Special Joint Study Group C in its reply asks for comments from broadcasting authorities on the noise objectives to be forwarded to the CMTT, which will have to reconsider these objectives under its new terms of reference. 6.5 The CMTT considers that in future all matters concerned with the revision of C.C.I.T.T. Recommendation J.21 should be dealt with by the CMTT. This Report should be brought to the attention of Study Group XV of the C.C.I.T.T.

REPORT 493 *

COMPANDORS FOR PROGRAMME CIRCUITS (Study Programme 5-1E-1/CMTT) (1970) 1. Introduction Two documents were studied under this programme: Doc. CMTT/9 (Canada) and Doc. CMTT/24 (United Kingdom). Doc. CMTT/9 describes the subjective testing of the programme compandor used in Canada. In the discussion on this document, Canada stressed that these results only apply to this particular type of compandor. This point is further discussed and emphasized in Doc. CMTT/24 which has been used, together with some additional material from the Federal Republic of Germany, to form the rest of this Report.

2. The problem being studied The maximum degree of noise reduction obtainable by the use of a compandor is achieved only in the absence of a signal. In the presence of a signal, the gain of the expander rises, and the amount of noise from the transmission circuit reaching the output of the system is therefore increased. The broadcasting authorities have been asked to provide information on the amount of such “expanded” noise that can be accepted when a compandor is used on

This Report was adopted unanimously. — 283 — Rep. 493

a programme transmission circuit, to provide information relevant to the study of Study Programme 5-1E-1/CMTT. It should be considered to what extent the load on the line is increased by the compressor, because a compandor reduces the noise by increasing the power of those portions of the programme, which are of smaller energy.

3. Factors determining noise impairment The subjective impairment produced by noise in a programme circuit cannot be expressed, as in a telephone system, by a readily definable quantity such as a percentage articulation score. The extent to which the listener’s enjoyment of the programme is disturbed by the presence of noise depends on a number of factors, few of which are capable of being precisely specified. In the case of a compandored circuit the situation is complicated by the fact that the “ expanded” noise level fluctuates with programme level and may on that account be more obtrusive than a steady noise of the same average power. The main factors which affect the audibility of “expanded” noise may be classified as follows: — the spectrum of the noise in relation to the spectrum of the programme material; — any variation in companding action with frequency, e.g. whether the companding action is applied uniformly over the full frequency range of the system, or whether the frequency range is split into two or more bands, each provided with an independent compressor and expander; in the latter case, the number of bands and their location in the spectrum is relevant; — the gain variation of the expander as a function of signal level, e.g. whether this gain— and hence the “expanded” noise—increases gradually or rapidly with signal level, and, if the latter, whether the transition from the minimum gain to the maximum gain takes place at low or at high levels; — the dynamic characteristics of the expander, which determine the length of time for which any increase in the expander gain—and hence in the noise—persists after cessation of the signal which gave rise to it.

4. Measurement of “ expanded” noise The “expanded” noise is present only when the programme signal is present, and cannot, therefore, be measured directly. It is conceivable that after a particular operating condition has been established by subjective tests on the programme as representing, for example, “just perceptible” impairment, one or more test signals could be substituted for the programme and the resulting noise measured by appropriate filtering. However, apart from the obvious difficulty of devising suitable test signals, it should be noted that the information obtainable from such a test is not in a form directly applicable in practice. The test should be such as to give a direct answer to the questions: — whether a given type of compandor is usable under given circumstances; — which of several types of compandor will allow of the greatest amount of noise in the transmission system taking account of the load on the line. It is therefore suggested that no attempt should be made to measure “expanded” noise as such, but rather that tests should be aimed at determining, for each type of compandor, the maximum amount of noise that may exist on the transmission system without the noise heard in the presence of a programme exceeding the tolerable limit. If, at any time, a correspond ing maximum noise determination were carried out with the compandor in operation but in the absence of programme, the difference between the two figures (in dB) should give a measure of “expanded” noise.

5. A practical method of measurement A circuit is arranged so that the same programme material can be transmitted alterna tively through either a path containing the compandor under test, or through a path without Rep. 493 — 284 —

a compandor. Independently controllable noise can be applied to either path, that applied to the compandor being injected between the compressor and expander.

With the noise power applied to the compandored path held constant, the noise power applied to the other path is varied until the subjective assessment of the listener is the same for both paths. The difference between the noise powers applied to the two paths is the subjective reduction of noise by the compandor. This can be repeated for several values of the noise power applied to the compandored path.

If the same test is made in the absence of a programme (in which case the test can be made also with measuring sets), the difference between the noise powers applied to the two paths is the objective reduction of noise by the compandor. The objective reduction is in general somewhat higher than the subjective reduction depending on the compression characteristics used. The difference between the figures (in dB) is the above-mentioned measure of “expanded” noise.

Care must be taken that the programme material used for the tests is as noise-free as possible, in order to avoid false results. In particular tape-recorded programmes may be troublesome.

Tests carried out by the Italian Administration using a compandor operating in the carrier frequency range showed that this method of measurement is satisfactory. Similar compandors are used by the Federal Republic of Germany and by a number of other European Administrations.

6. Subjective tests performed on one type of compandor The essential features of the subjective tests described by Canada in Doc. CMTT/9 were: — the path between compressor and expander was band-limited to 8 kHz and contained pre- and de-emphasis networks; — wideband “white” noise was injected after the pre-emphasis network; — the attack and recovery time of the compandor, as defined in C.C.I.T.T. Recommendation G.162 (Blue Book, Vol. Ill, p. 58) are 20 ms and 75 ms respectively in both the compressor and expander; — a panel of 2 0 expert listeners was used. The results showed that the type of programme material used had a substantial effect on the “just detectable” impairment by modulation noise. Compared with an average pro gramme, 8 dB more noise could be tolerated with dance or Dixieland music whilst 6 dB less was detectable on time-signal pips.

The programme-weighted maximum signal-to-noise ratio which was just detectable when using the more susceptible types of programme materials is in the range 45 to 40 dB. A limit of 42-5 dB has been adopted in Canada for programme circuits to be used in conjunc tion with compandors.

7. Further information

Further information on compandors is available in the documents of the C.C.I.T.T. which are related to Question 7 of Study Group XV of the C.C.I.T.T.

8. Conclusion

It is concluded that the study can be best continued under the Study Programme 5-1E-1/CMTT. — 285 — Rep. 494, 495

REPORT 494 *

TRANSMISSION OF SOUND PROGRAMME SIGNALS OVER LONG DISTANCES (Question 5-1/CMTT) (1970) Methods of measurement and monitoring of programme circuits are included in the aim of Question 5-1/CMTT. It is noted that Recommendation 467 describes the technical characteristics to be checked for frequency-modulation stereophonic broadcasting using the pilot-tone system. In this Recommendation the following parameters are included in those given for measure ment during periods of test and adjustment: — the frequency response of the M and individual A and B channels; — harmonic distortion in the individual A and B channels; — the signal/noise ratio in the individual A and B channels; — the crosstalk attenuation between the A and B channels; — the crosstalk from the main channel M into the stereophonic sub-channel, and from the stereophonic sub-channel S into the main channel; — the frequency of the pilot signal; — the degree of suppression of the sub-carrier; — the phase of the sub-carrier relative to the pilot signal. Consideration should be given to the extent to which these parameters could be usep for the measurement and monitoring of programme circuits and what additional parameters should be used.

REPORT 495 *

NOISE FROM THE POWER SUPPLY (1970) Study Programme 5F/CMTT was solely concerned with studying a limit to be recom mended for noise due to modulation of the programme signals by signals from power supply sources. The authors of Docs. CMTT/27 (United Kingdom), CMTT/32 (L. M. Ericsson) and CMTT/36 (Netherlands) agree that the limit of —45 dBmO for the strongest unwanted side component, when a sine-wave signal is applied at the level of 0 dBmO, which is acceptable for circuits for FM and AM-VF telegraphy, facsimile transmission, speech, telephone signalling and data transmission ** is also acceptable for circuits for programme transmission. This limit applies to a programme circuit of any bandwidth. Doc. CMTT/36 quotes a limit corresponding to a ratio of 57 dB but this applies for the most critical modulating frequencies, the worst modulating frequencies being multiples of 4 kHz within the transmitted band (4 and 8 kHz). At the lower modulating frequencies the ratio of 45 dB is considered admissible by the Netherlands. Note, — See also Recommendation 474.

* This Report was adopted unanimously. ** See § 1.3.1 of the Annex, page 382 1 of Volume V of the C.C.I.R., Oslo, 1966. Rep. 496 — 286 —

REPORT 496 *

CIRCUITS FOR HIGH- QUALITY MONOPHONIC AND STEREOPHONIC TRANSMISSIONS

(Study Programmes 5-1A-1/CMTT and 5-1B-1/CMTT) (1970)

1. Characteristics of circuits for high-quality monophonic and stereophonic transmissions over long distances

1.1 Report 293-2, submitted to the CMTT by C.C.I.R. Study Group 10, contains a table showing the overall values applicable to impairments affecting the quality of stereophonic reproduc tion. These values are based on subjective tests and therefore apply generally to all the elements constituting the stereophonic sound transmission chain, including the sound-programme circuit. The overall values of the parameters in question will be found in Table I and the figures of the aforesaid Report. With regard to noise parameters, the CMTT considers it useful to point out that on a circuit the figure for signal-to-weighted noise ratio (r.m.s. value) refers to a signal of an amplitude equal to 100% of the maximum permissible level. This corresponds to a level of + 9 dBmO on a sound programme circuit.

1.2 A perusal of the overall values proposed in Report 293-2 shows that in order to meet quality requirements at the end of the chain it is desirable to have international sound programme circuits with the parameters specified in the 40 Hz to 15 kHz frequency band. With a view to drawing up specifications for these circuits, the CMTT has undertaken to assign part of the overall tolerances to the hypothetical reference circuit.. As it is stated in Report 488, the parameters for monophonic transmission circuits have been studied jointly with those for stereophonic transmission circuits.

Doc. CMTT/10 (1966-1969) submitted by the E.B.U. on this question contains a table proposing, for the essential parameters, some tolerances applicable to a stereophonic circuit of 2500 km comprising three sections, i.e., with two points of audio-frequency connection. It became apparent, first, that some of the proposed values have had to be modified to take maintenance needs into account and, secondly, that other specific circuit parameters have had to be added to the Table.

Table I gives a list of the parameters for a monophonic circuit, with the values that should be respected during programme transmission. Additional parameters for a stereo phonic circuit appear in Table II. As is stated in the footnotes, parameters 3.3, 5.3, 8.2 and 11 for which no tolerances are given, need to be studied further. The same applies to para meter 10, the provisional value of which will have to be reviewed. It should also be noted that the value given for crosstalk ratio of a stereophonic transmission circuit excludes the separate use of each of the two circuits for monophonic transmission.

The effect of crosstalk introduced by the stereophonic circuit on overall crosstalk has been studied in Italy (Doc. CMTT/165, 1966-1969). From the curves in Fig. 1 taken from this document the required crosstalk at the input of a transmitter-to-receiver chain with specific amplitude and phase characteristics can be determined.

The CMTT invites the interested organs and Administrations, especially the competent Study Groups of the C.C.I.R. and the C.C.I.T.T., to express their views on all the parameters and values proposed in this Report which, at the present stage of the work of the CMTT, are considered only as a basis for further study.

* This Report was adopted unanimously. — 287 — Rep. 496

1.3 Many contributions on tolerances for monophonic and stereophonic transmission circuits were received by the CMTT during the period 1966-1969. They describe tests carried out in several countries on national circuits in operation and over distances up to 2500 km. On the basis of the information given in these documents, the CMTT considers that the study of methods of stereophonic transmission over long distances should be limited to the following two cases: — separate transmission of signals A and B; — transmission of signals M and S in the form of the stereophonic multiplex signal modulating the broadcasting transmitter. Contributions concerning the first method were submitted by Italy (Docs. CMTT/63 and 145), the Federal Republic of Germany (Doc. CMTT/162) and France (Doc. CMTT/163). It should also be noted that France (Doc. CMTT/61) and Japan (Doc. CMTT/135) use radio-relay systems transmitting a picture accompanied by several frequency-multiplexed sound channels. The second method is used in the United Kingdom (Doc. CMTT/128) and the Nether lands (Doc. CMTT/133). The arguments in favour of this solution are based mainly on its operational aspects: elimination of the need for an encoder, which therefore does not have to be switched at the transmitter, impossibility of phase inversion and use of the pilot signal to monitor continuity.

1.4 Doc. CMTT/164 (France), 1966-1969, draws attention to the need to specify additional para meters when pulse code modulation systems are used to convey sound programme signals. The CMTT considers that the quality tolerance given in Table I should be applicable to high qua lity sound programme circuits provided by means of pulse code modulation. A study of the additional parameters to be specified and the appropriate quality tolerances will be made when C.C.I.T.T. Special Study Group D has indicated the likely range of fundamental character istics for analogue to digital converters for programme circuits, e.g. sampling rate, number of digits per sample, type of coding, companding characteristics. As this range of fundamental characteristics will be affected by decisions concerning basic PCM systems for telephony and the higher order hierarchy for higher speed systems, the CMTT considers that due account should be taken of the requirements of programme circuits when these matters are decided. Rep. 496 — 288 —

T a b l e I Parameters of high quality circuits for monophonic transmission

No. Parameter 2500 km reference circuit with 3 sections

1 . Nominal bandwidth 0 04 to 15 kHz

2 . Insection gain at 0-8 or 1 kHz 2.1 Adjustment error (x) ±0-5 dB 2 .2 Long-period variation, between two adjustments ±0-5 dB

3. Amplitudefrequency respon- j 125 +0-5 to - 2 dB se referred to 0-8 or 1 kHzQ) j £ 125 |° J® +0-5 to -0-5 dB +0-5 to - 2 dB

4. Difference between group delay i 0 04 kHz < 55 ms at the given frequency and its < 0 075 kHz < 24 ms minimum value [ 15 kHz < 8 ms

5. Noise power (2) 5.1 Weighted (3) < — 51 dBmOps 5.2 Unweighted (4) < -41 dBmO 5.3 Impulsive noise (5)

6 . Single tone interference measured selectively (6) -73 - Aps dBmO (see Note)

7. Disturbing modulation by power supply related to signal level (7) > 45 dB

8 . Non-linear distortion 8.1 Harmonic factor (8) 0 04 to 0125 kHz < 1 % 8 .2 Intermodulation within the channel (9) 0125 to 5 kHz <0-5%

9. Error in reconstituted frequency < 1 Hz

1 0 . Crosstalk ratio (10) 0-04 to 15 kHz 74 dB

1 1 . Amplitude I amplitude response (u)

Note to point 6 above: A*> = correction for the frequency being measured in accordance with the new weighting characteristic described in § 2.2 of this Report. — 289 — Rep. 496

T a b le II Additional parameters for stereophonic transmissions

2500 km reference circuit No. Parameter Frequencies (kHz) with 3 sections

0 04 to 0125 1-5 dB 1. Level difference A and B 0125 to 10 0-8 dB 10 to 15 1-5 dB

004 30 degrees 004 to 0-2 oblique segments 2. Phase difference A and B 0-2 to 4 15 degrees 4 to 15 oblique segments 15 30 degrees .

3. Crosstalk ratio A and B 3.1 Measured selectively at the fundamental frequency 0 04 to 15 50 dB 3.2 Measured selectively at a harmonic frequency 0 04 to 15 60 dB 3.3 Single overall measurement using a weighted noise signal (12)

C1) Values given in the case of adjustment of gain (No. 2.1 of Table I) or frequency response (No. 3 of Table I) at the end of the circuit and for the whole link. The values given may only be obtainable by use of an additional equalizer at the end of the complete link. (2) Circuits may exceed these values for a small percentage of time. This problem is being examined by C.C.I.R. Study Group 9 for radio-relay systems and by C.C.I.T.T. Study Group XV for cable systems and the CMTT would like all the available information on this subject to be brought to its knowledge. (3) The value given is to be met when using the existing programme weighting network. This should be replaced by the value to be met when using the new weighting network referred to in § 2.2 of this Report in the light of the subjective tests described in § 2.1. (4) Both the requirements for weighted and unweighted noise are to be met. (6) The method of measurement and the tolerance will have to be studied. C.I.S.P.R. Publication No. 1 contains inform ation which may be useful in this regard. (6) — The value measured (selectively) will need correction in accordance with the new weighting characteristic. There is doubt as to the use of the weighting characteristic for this purpose and this method of expressing the requirement is provisional prior to receiving the results of subjective tests. — To obtain the given value when, for example, there is interference from a carrier frequency, a rejection filter may need to be inserted. A study should be made of the parameters to be specified for this filter so that its adverse effects on parameters Nos. 3 and 4 are reduced to a minimum. The following two studies on this subject have been published: B u c k l e i n , R. Audibility of irregularities in the frequency response in acoustical transmission (in German). Fre- quenz, Vol. 16, 3, 103-108 (1962). F l o h r e r , W. The deterioration of the naturalness of speech due to gaps in the transmission frequency band (in German). Frequenz, Vol. 22, 6, 175-178 (1968). 0) Conforming to Recommendation 474, the value for higher frequencies has to be determined. (8) The CMTT considers it necessary to measure non-linear distortion for frequencies above 5 kHz. The method of measurement needs to be studied. (9) The Administrations of the Federal Republic of Germany and the United Kingdom are continuing their studies of methods of intermodulation measurement and will soon be in a position to announce the results. A new test signal fbr intermodulation tests is proposed in Report 497. In view of the importance of specifying intermodulation, the CMTT would like other Administrations to send it inform ation on the most suitable methods of measuring this parameter and on the values that should be specified. (10) The study of the objective assessment of crosstalk corresponding to the subjective effect is being conducted in the CMTT. Pending the completion of this study, it has been agreed to indicate for this parameter the value adopted for 10 kHz circuits. This value will have to be reviewed later. (“) The purpose of this parameter is to take into account the effect on the signal of the use of compandors in links. Methods of measurement and tolerances will have to be studied. (12) Certain countries have elaborated for broadcasting purposes a method of measuring crosstalk using weighted noise (see Report 403-1 and Report 497). A study should be made to see whether this method could be applied to links. Rep. 496 — 290 —

Figure 1

d : crosstalk between A and B signal channels at the input of M and S systems K : amplitude difference between M and S signals due to transmission system 9 : phase difference between M and S signals due to transmission system D : crosstalk between A and B signal channels at the output of M and S systems — 291 — Rep. 496

2. Subjective tests and measuring methods for high quality circuits

2.1 Subjective effect o f noise and crosstalk

To carry out this study the CMTT considers that it is necessary:

— to outline the problems in carrying out subjective tests on noise (which includes crosstalk); — to propose a list of suitable signals of interference; — to propose, if possible, a test method or methods. The CMTT considers that its task is to take into account noises of all kinds found within the broadcasting chain. Special consideration must be given to intelligible crosstalk (telephony or sound programmes) that may cause the listeners to take special notice of what they hear. Another form of interference, that is, continuous sine-wave tones, must receive special attention as unless precautions are taken in the listening room standing waves are likely to produce minima and maxima of sound intensity, and these tones are not likely to be masked by the programme items. Both intelligible crosstalk and continuous sine-wave tones will have to be reduced to a lower intensity than other types of noise.

The subjective tests described below are devised for a system that transmits a band of frequencies from 40 Hz to 15 kHz. The results obtained are not necessarily suitable for lesser bandwidths, as for instance type A programme circuits as specified by the C.C.I.T.T. The following information will assist in carrying out subjective noise and crosstalk tests. Programme items and sample noises are recorded on tapes available on application to the C.C.I.R. (see Note 1).

2.1.1 The observers It is recommended that the results obtained from the specialist and non-specialist observers be presented separately. A suitable number of observers is, say, 20 but these should be tested in groups of 6 or 8 , and they should be seated within the capability of the loudspeaker to present high quality reproduction to all of them. 2.1.2 Ambient noise in listening room It is recommended that where the ambient noise is to be raised in the listening room that the added noise signal should not be white noise but a signal more typical of ambient noise. This added noise should give a reading on a sound level meter (an instrument complying with the IEC standard specification for precision sound level meters and with the American standard ASA SI.4-1961) of 30 dB. A recording of this noise will be supplied together with details of the method used to obtain it. It is recom mended that the loudspeaker providing the added ambient noise should be placed on top of the speaker being used for the test tapes. 2.1.3 Type of programme item Five types of programme have been selected: — orchestra; — piano; / — chamber music; — speech (male); — speech (female). 2.1.4 Test noises (a) hum (50 H z+ harmonics); (b) crosstalk of vision on sound channel on a multi-channel FDM system. (Vision signal supplied from a generator to provide a pattern of horizontal and vertical lines); Rep. 496 — 292 —

(c)* direct current signal (clicks) from a teleprinter; (d) unintelligible crosstalk (speech); (e)* intelligible crosstalk (speech in German); (f) noise from tape recording; (g) empty studio noise; (h) 3 kHz sine-wave tone (steady); (j) 10 kHz sine-wave tone (steady); (k) white noise; (I) triangular noise; (m) voice frequency dialling; (n)* intelligible crosstalk (music); (o)* data transmission signals.

Noises (h) and (j) may be supplemented by additional sine-wave tones if this is thought desirable by the experimenter.

Noise from exchange switching operations will be provided if a suitable sample can be obtained.

Referring to noise item (e), this should be replaced by an item of subjectively the same loudness in the appropriate language and should have a 6 dB per octave slope on the frequency characteristics. The views are sought of C.C.I.R. Study Group 10 and C.C.I.T.T. Study Group IV on the list of noises to be used. 2.1.5 Bandwidth o f test reproducing system The bandwidth of the reproducing system must be clearly documented (the loudspeaker should be included). The suggested bandwidth should be 40 Hz—15 kHz. 2.1.6 Measuring instruments The only signal levels to be recorded by the experimenter during the tests are the line-up tones (sine waves) on the tapes and therefore the type of meter used is not important. For reference purposes full documentation will be provided giving the relationship between the levels of the line-up tones and the levels of noise and programme on the tapes, using suitable electrical measuring instruments.

2.1.7 Listeners preferred maximum listening levels on programme items Suitable listening levels for loud passages of the various items, as read on a sound level meter, with weighting C, are as follows:

— orchestra 85 dB — piano 85 dB — chamber music 81 dB — speech (male) 85 dB — speech (female) 73 dB.

As indicated in § 2.1.11 below, the listening levels actually used in the experiments are to be measured by a sound level meter using a band of random noise recorded on the programme tape? To facilitate a comparison between the results obtained by different organizations, the experimental data for individual items must be given separately.

* These noises have been simulated with a network to provide a 6 dB per octave slope into the frequency characteristic. — 293 — Rep. 496

2.1.8 The test tapes As no organization has submitted stereophonic noise recordings, all material will be recorded monophonically. Problems of tape synchronization make it imprac ticable to change both programme and noise items in successive presentations. Since noise items are to be presented in random order (see § 2 .1 .1 0 ), it follows that each programme tape will consist of repetitions of a particular programme item, so that the total playing time equals that of the noise tape. Each programme tape will contain a loud passage followed by a quiet passage from the same item repeated over and over again. The playing time of the tapes is 10 minutes.

2.1.9 Sample programme items The speech items used should, in every case, be in a language appropriate to the authority carrying out the tests. Items in English will be included on the test tapes; these should be replaced by speech of a similar character in the appropriate language and at a level judged to be subjectively the same.

2.1.10 Method o f presenting noises to observers The observers will carry out the tests in groups, and the noises will be presented in random order at levels to be set by the experimenter. It is suggested that these levels should be changed in steps of 5 dB. Six different noise tapes will be provided, each giving a different noise sequence. The experimenter should guard against causing fatigue to observers. Listeners should use the scale of comment as set out in Note 5 of Report 405-1. 2.1.11 Line-up procedure A comprehensive line-up procedure will ensure that all the necessary information on the signal-to-noise ratios may be calculated from the line-up tones at the output of the tape recorders and from the data supplied. The listening levels which the experimenter decides on can be specified in terms of measurements of random noise. Thus there is no need to measure programme levels with a sound level meter. The tapes will be documented individually when issued with levels of noise and programme, the noise being measured with a DIN noise meter and the programme being measured with an E.B.U. programme meter.

2.1.12 Announcements on the tape It is proposed that two tracks will be provided on the noise tape, one will be for recording noise (at a high level) and the second one for announcements in English to assist the experimenter. The experimenter on hearing these announcements will be able to speak to the observers about the progressing of the tests in the appropriate language. 2.1.13 Instructions to observers The observers should be instructed to judge the noise in terms of the annoyance value, that is, how the noise impairs the enjoyment of a programme. They should not judge only the loudness of an interfering noise.

2.1.14 Evaluation o f results For guidance of evaluation of results some appropriate statistical methods are described in:

J. P. G u i l f o r d , Psychometric methods. McGraw-Hill, New York, Toronto, London (1954).

B. R. P a u l i ' and W. A r n o l d , Psychologisches Praktikum (Psychological methods). Gustav Fisher Verl., Stuttgart, 30 (1967).

M. G o s e w i n k e l , Lautstarkemessung (Konstanzverfahren) (Measurement of sound intensity—constant method). DIN-Mitteilungen Band 37, H.6 , 253 (1958). Rep. 496 — 294 —

Note 1. — Copies of the test tapes of noise and programme items are available from the Director of the C.C.I.R. so that tests for subjective noise and crosstalk may be made.

Note 2. — It is possible that notch filters may be fitted to carrier programme circuits in order that interfering tones may be rendered inaudible. There may be therefore a need to carry out subjective tests to discover the effects of using stop filters on carrier programme circuits. See Bibliography under Note 6 of Tables I and II.

B ibliography : C.C.I.R. Doc. CMTT/67 (Italy), 1966-1969.

2.2 Weighting network for audio-frequency noise measurements

2.2.1 The CMTT appreciates that the work on Study Programme 2A/X has led to a draft Recommendation of a weighting network for measurement of audio-frequency noise for broadcasting and in sound-recording systems. Some remarks on this subject seem to be necessary. In the last years much work has been done in several countries on Study Programme 2A/X in order to find the most appropriate weighting network and measuring instrument which will give a close agreement between the measured noise value and the subjective assessment for as many as possible kinds of noises * (e.g. random noise, noise of more impulsive character, etc.) occurring on facilities for pro gramme transmission. This work has also been necessary because of the greater demand for 15 kHz programme circuits as the weighting network referred to in Recommendations J.21, J.31, J.41 and P.53 only covers frequencies up to 10 kHz.

As a result of the research, two proposals for the weighting network were made by the O.I.R.T. (Doc. X/155, period 1963-1966) and by the Administration of the Federal Republic of Germany (Doc. X/23, period 1966-1969), the frequency responses of which are in good agreement with each other. Further investigations carried out by the B.B.C. Research Department (Doc. X/22 (United Kingdom), 1966-1969) combining these weighting networks with different measuring instruments showed that the weighting network proposed by the Federal Republic of Germany in combination with a modified NIESE-type meter gave the best results in accordance with subjective assessment.

During the Interim Meeting at Palma de Mallorca in April/May 1968, Study Group X adopted a draft Recommendation (Doc. X/108, Doc. CMTT/47 and conclu sions of the Interim Meeting of Study Group X, pages 30 to 32) which recommends that for the measurement of audio-frequency noise for broadcasting and in sound- recording systems a network should be used, the frequency response of which is given in the form of a curve in Fig. 1 of Doc. X/108 and in the conclusions in the form of tabulated values.

2.2.2 It will be advantageous to add to this table values for the most common edge-frequencies of the transmission band and include tolerances for the realized network. These values are given in Table IV. As to the tolerances, the most stringent requirement has been put at 6 kHz, as energy in the region of this frequency will usually contribute the most to the weighted noise power measured. The network shown in Fig. 2 will generate the weighting curve with adequate accuracy, the associated amplifier being adjusted to obtain an insertion gain of 12-3 dB at 6 kHz. It is considered that the opinion of C.C.I.T.T. Study Group IV on this point would be useful so that appropriate measures may be defined for the maintenance of the measuring equipment.

* This, however, does not refer to single-tone interference. Studies carried out in the Federal Republic of Ger many have shown that the weighted single-tone level has to be about 20 dB below the weighted noise level for sufficient masking. — 295 — Rep. 496

The CMTT is of the opinion that the weighting network defined in Recommen dation 468 should be used also for noise measurements on transmission links. In doing this an important point has to be considered: the frequency response of a weighting network referred to 1 kHz gives no indication for the tolerable signal-to-noise ratio. In consequence of this the noise objective for the transmission link has to be reconsid ered and revised if the weighting network is changed. As a guide for this, Table III gives the calculated conversion figure 8 which is to be understood as the difference between the noise levels measured with the proposed weighting network and the existing one.

T a b le I I I

Conversion figure 8

Equivalent noise objective referred to a signal-to- Noise Bandwidth 8 noise ratio o f 57 (dB) (kHz) (dB) (Recommendation J21) (dB) 10 4 5 7 - 4 =53 White 15 0 4-4 57 - 4-4 = 52-6

10 5-5 57 - 5-5 = 51-5 Triangular 15 0 6-6 57 - 6-6 = 50-4

(x) For the calculation the frequency response of the existing weighting network in the frequency region from 10 to 15 kHz has been taken as it is with the type of noise measuring set generally used in the Federal Republic of Germany. It is expected that with other noise measuring sets rather similar values will be otained.

It is to be seen from Table III that the conversion figure depends on the noise distribution and the bandwidth. The CMTT considers that for any particular bandwidth, only one noise objective should be specified regardless of the spectral distribution of the noise. Further study is, therefore, necessary to find the appropriate conversion figure in order to adapt the Recommendation J.21 noise objective of 57 dB to the proposed weighting network. It is noted that Study Group 10 is continuing the study of a suitable measuring instrument to be used with the weighting network. 2.2.3 In proposing the use of this weighting network for noise measurements on transmission links, the CMTT considers that the same weighting network should be used for noise measurements on all component parts of its broadcasting chain. Rep. 496 — 296 —

The CMTT considers that a different network is now required for 10 kHz circuits and the wider-band transmission systems now being considered and that this network will probably not be unsuitable for use on the narrower-band circuits. The proposed network gives results more in accordance with subjective assessment when used with most existing types of noise measuring instruments. The agreement of the C.C.I.T.T. to this proposal is sought.

T a b l e IV Frequency response of the proposed weighting network for noise measurements with sound programme transmission

Frequency (Hz) Attenuation (dB) Tolerance (dB)

30 30-6 40 280 ± 2 -0

50 260 60 24-5 1 0 0 2 0 0 ±1-5 2 0 0 13-9 400 7-9 800 1-9

1 0 0 0 0 0 ± 1 0 2 0 0 0 - 5-8

3 000 - 8-8 4 000 - 10-7 ±0-5 5 000 - 11-8

6 0 0 0 - 12-3 ± 0 0

7 000 - 1 2 1 8 0 0 0 - 1 1 -2 ±0-5 9 000 - 1 0 0 1 0 0 0 0 - 8-1

11 0 0 0 - 5-5 1 2 0 0 0 - 2 -2 ± 1 0 13 000 1-7

14 000 5-5 15 000 90 ±1-5

16 0 0 0 12-5 ± 2 0 2 0 0 0 0 2 2 -2

31 500 35-7 ± 3 0 — 297 — Rep. 496

Appropriate network to generate the weighting function

All component values to be within ± 1 % Q-factors of the coils should be better than 200 at 10 kHz Rep. 497 — 298 —

REPORT 497 *

CIRCUITS FOR HIGH QUALITY MONOPHONIC AND STEREOPHONIC TRANSMISSIONS A proposed test signal and weighting network for use in making tests for linear and non-linear crosstalk and/or non-linearity (Study Programmes 5-1A-1/CMTT, 5-1B-1/CMTT and 5-1D-1/CMTT)

(1970)

1. Introduction

The following is a proposal by the Federal Republic of Germany and the United Kingdom for a standard test signal for use in making non-linearity tests and crosstalk. It could also be used generally for simulating a programme signal to be transmitted over high quality programme circuits where a high amplitude signal containing a large proportion of energy at the higher frequencies is needed. The main characteristic of this signal would be obtained by a Gaussian white noise generator followed by a weighting network.

2. Reason for use

It is desirable to devise a suitable test signal for measuring linear and non-linear cross talk and/or non-linearity of sound programme circuits. This signal should meet the require ments of C.C.I.T.T. Study Group IV and C.C.I.R. Study Group 9, that the test signal shall not cause undue interference in other circuits forming part of a composite system.

3. Characteristics of the proposed weighting network

The characteristic of the proposed new weighting network is based upon that given in Report 399-1 of the C.C.I.R. Referring to curve B, Fig. 1 of the Annex of that Report, the char acteristic represents a long-term mean value of the sound programme signal. Because it is desirable to check non-linearity and crosstalk using a signal of high loading value account has been taken of the C.C.I.T.T. values of 1 % for conventional loading (see C.C.I.T.T. Recom mendation G.223). Therefore it is proposed that the slope of the characteristic curve of the weighting network should be devised taking into account that at moments of maximum load ing the proportion of the energy at the higher audio frequencies may often be relatively large; while curve B of Fig. 1 of the above-mentioned Annex at the higher frequencies has a slope of 5 — 8 dB per octave, it is proposed that the new curve shall slope more gently (see full line on attached curve). The circuit of the weighting network is also shown with the attached curve.

4. Circuit loading using this standard test signal

The standard test signal is obtained by applying the test signal to the sound programme circuit at a total power of 1 mW at a point of zero relative level, i.e. where the nominal peak signal level is equal to that of a sine wave having a power of 8 mW (see Recommendations J.13 and N.12 of the C.C.I.T.T.). It has been found by the Federal Republic of Germany that the use of the standard C.C.I.T.T. pre-emphasis network for carrier programme circuits increases the mean load by only 1 or 2 dB taking long-term averaging of a typical programme. Also the use of pre-

* This Report was adopted unanimously. — 299 — Rep. 497 emphasis means that the maximum loading of signals of higher energy is increased by 5-5 dB. The newly proposed standard test signal will provide an increased loading (when the C.C.I.T.T. pre-emphasis network is used) of 4 0 dB. This value is only 1-5 dB less than the higher signal loading of 5-5 dB. This proposal for a standard test signal should be studied further and trials made to find out its usefulness.

Bibliography

1. Holbrook, B.D. and Dixon, J.T. Load rating theory for multi-channel amplifiers. B.S.T.J., 624-644 (1939). 2. Fischer, G. and Rasch, J. Die bei Fernsprech- und Rundfunkfibertragung auftretenden elek- trischen Leistungen unter Berficksichtigung von Preemphasis und Kompander (Electrical powers occurring in telephone and programme transmission, allowance being made for pre-emphasis and compandors). NTZ, 18, 4, 205-209 (1965). 3. von Guttenberg, W. and Hochrath, H. Untersuchungen fiber die Gerauschverminderung mittels Pre- und Deemphasis bei Rundfunkfibertragung (Inquiries into noise reduction by pre-emphasis and de-emphasis in programme transmission). NTZ, 12, 9, 467-474 (1959). Proposed network

6000 0,68 (iF dP ^ ) <~=l ’ 0,8 H ^ 5 ^ 0 6 8 ^ 6000

Figure 1

• • • Proposed weighting characteristic for making tests for non-linearity and crosstalk Characteristic as taken from C.C.I.R. Report 399-1 — 301 — Rep. 498

REPORT 498 *

TRANSMISSION OF SOUND PROGRAMME SIGNALS OVER COMMUNICATION-SATELLITE LINKS (Study Programme 5-1G/CMTT) (1970) 1. Introduction Communication-satellite links can be used to transmit sound programme signals and related auxiliary signals such as those used for commentary, cue control and engineering service purposes. These sound signals may, or may not, be accompanied by an associated television signal. With a view to facilitating study of the general characteristics of the sound broadcasting circuits and the auxiliary circuits mentioned in the Study Programme 5-1G/CMTT the following Report gives information on the arrangements proposed in the INTELSAT III system and in a project under study by the E.B.U. Reference can also be made to Report 488, which gives information on the sound transmission channel provided by the MOLNIYA and ORBITA systems.

2. INTELSAT system arrangements

With the introduction of satellites of the i n t e l s a t III class a television signal can be accompanied by a variety of audio services [1, 3]. The audio signals are combined in a baseband, containing programme sound with cue and commentary circuits, and this is sent from the transmitting earth station as a standard 12-channel telephony group (C.C.I.T.T. “A” group) With engineering service channels below 12 kHz. Provision is made for a 10 kHz (C.C.I.T.T. Type A) programme circuit, the remaining channels in the group being available for use as channels for the cue and commentary circuits. The return channels for the cue and commentary circuits are returned from one of the receiving earth stations in a corresponding 12-channel audio baseband. Additional capacity requirements can be met by adding another 12-channel telephony group (C.C.I.T.T. basic “B” group) and this arrangement then provides a maximum of two programme channels together with about 18 telephone quality channels, some of which are used with return chan nels to form circuits. All these telephony channels and circuits can be used for cue, commentary or auxiliary purposes.

3. E.B.U. “ Eurovision” satellite project The European Broadcasting Union is considering the use of communication satellites for distributing the Eurovision programmes over a region covering Europe, the Middle East and Africa [2]. Some of the quality characteristics for the space section that might be required at the output of a receiving earth station in the operational system are listed below. They are based on studies carried out by the E.B.U. and its member organizations in relation to the Euro vision satellite project and on studies conducted by the C.E.T.S. and the E.S.R.O./O.E.R.S. Quality o f the “ international-sound” channel When a sound component of broadcast quality (“international sound”) accompanies the television picture, it is proposed that the corresponding channel should meet the following requirements measured at the output of the receiving earth station: — audio-frequency bandwidth 12 kHz — unweighted signal-to-noise ratio at least 57 dB for 99 % of the time

This Report was adopted unanimously. Rep. 498 — 302 —

Quality o f commentary channels The channels which convey, for example, the commentaries in several languages required for television outside broadcasts should in principle have at least as good quality as a telephone circuit, so that the audio bandwidth transmitted should cover the range 300 to 3400 Hz. As regards the noise, it seems at first sight difficult to draw up a reasonable specification. On the one hand, it is desirable to be able to transmit, in addition to the pictures and the international sound, a fairly large number of commentaries (e.g. around 20). To that end, the commentary channels are multiplexed, so that they may be transmitted by means of a sub carrier. It can be shown by calculation that if the signal-to-noise ratio of a demodulated commentary channel is high, that is to say if the amplitude of the sub-carrier is high, the radio-frequency bandwidth needed with frequency modulation rapidly becomes incompatible with the demands of space systems. One possible solution of this problem would be to accept a moderate signal-to-noise ratio for the commentary channels, and to improve the subjective quality by using a com pandor. Using this method, it is proposed that the least favourable commentary channel should meet the following condition, at the output of the receiving earth station: — unweighted signal-to-noise ratio not less than 29 dB for 99 % of the time, in the presence o f a signal o f maximum permissible amplitude in the channel in question. It can be shown that in this fashion the “complete sound” consisting of the international sound mixed with one of the commentaries, will have on reproduction a quality approximately equivalent to that of a sound channel of unweighted signal-to-noise ratio of about 54 dB in the absence of a signal in the commentary channel, that is to say, when the noise in that channel would be most disturbing.

B ibliography -

1. C.C.I.R. Doc. CMTT/37 (U.S.A.), 1966-1969. 2. C.C.I.R. Doc. CMTT/62 (E.B.U.), 1966-1969. 3. International Telecommunication Satellite Consortium (INTELSAT). Doc. I.C.S.C.-37-38, W /l/69 (Attachment A, page 16, § C.3). — 303 — Q. 1-1/CMTT, S.P. 1-1B-1/CMTT

QUESTIONS AND STUDY PROGRAMMES, RESOLUTIONS AND OPINIONS (CMTT)

QUESTION 1-1/CMTT

TRANSMISSION OF TELEVISION SIGNALS OVER LONG DISTANCES

The C.C.I.R., (1970)

CONSIDERING that all the information required by the C.C.I.R. and the C.C.I.T.T. relating to the require ments for the transmission of monochrome and colour television signals over long distances is not yet available;

unanimously d e c i d e s that the following question should be studied: for the transmission of monochrome or colour television signals over hypothetical reference circuits or chains:

1 . what are the characteristics of the signal and of the circuit which must be considered, what are their recommended values, and what tolerances must be imposed to ensure satisfactory transmission;

2 . what methods of measurement and what test signals can be recommended for checking the characteristics ?

STUDY PROGRAMME 1-1B-1/CMTT

PERFORMANCE REQUIREMENTS FOR INTERNATIONAL TELEVISION CIRCUITS

The C.C.I.R., (1966- 1970)

CONSIDERING (a) that Question 1-1/CMTT, § 1, has not been fully answered; (b) that Recommendations 421-2 and 451-1 quote different values and tolerances for television transmission circuits for different television standards; (c) that it is often necessary for an international television circuit to carry, at different times, signals conforming to one of a number of the standards covered by Recommendations 421-2 and 451-1; (d) that it may be possible to define and build economically transmission circuits that are capable of carrying the majority of internationally established television systems;

unanimously d e c i d e s that the following studies should be carried out :

1 . unified testing methods that can be recommended for television circuits intended for the transmission of signals conforming to the majority of television standards; S.P. 1-1B-1/CMTT, 1-1C/CMTT — 304 —

2 . determination of unified performance objectives for the hypothetical reference circuit, permitting satisfactory transmission of signals conforming to the majority of television standards. Note. — Report 486 contains the information accumulated during the period 1966-1969 with respect to this Study Programme.

STUDY PROGRAMME 1-1C/CMTT *

INSERTION OF SPECIAL SIGNALS IN THE FIELD-BLANKING INTERVAL OF A TELEVISION SIGNAL

The C.C.I.R., (1962 - 1963 - 1966 - 1970)

CONSIDERING (a) that it is already current practice in a number of countries to insert special signals in the field-blanking interval of a television signal; (b) that such signals can be used for checking the performance of the circuits over which the television signal is transmitted; (c) that such signals might be used for supervision or various control purposes and for the transmission of information on the operation of international networks;

unanimously d e c i d e s that the following studies should be carried out:

1 . can special signals be inserted in, and removed from, the field-blanking interval of the tele vision signal, without detriment to the quality of the television picture itself;

2 . for what purposes should such signals be used internationally;

3. at which points in the international television connection should these signals be inserted and, possibly, be removed again;

4. what provisions should be made to avoid confusion between signals for national and inter national use; 5. what forms of special signal can be recommended for international use;

6 . what should be the position in the field-blanking interval of signals for measuring the charac teristics of television networks; 7. what should be the position in the field-blanking interval of signals associated with control functions and the transmission of operational information;

what would be the best system of encoding for the signals referred to in § 7 ?

This Study Programme replaces Study Programme 6A/CMTT and is identical with that text. — 305 — S.P. 1-1D/CMTT, 1-1E/CMTT

STUDY PROGRAMME 1-1D/CMTT

DAMPED VERY-LOW FREQUENCY OSCILLATIONS IN TELEVISION CIRCUITS OVER LONG DISTANCES

The C.C.I.R., - (1970)

CONSIDERING (a) that Recommendations 421-2 and 451-1 relate to the requirements for the transmission of television signals over long distances; (b) that, in addition to the linear waveform distortion referred to in § 3.5 and Part 2, § 4.9, respectively, of these Recommendations, a distortion in the form of a damped very low frequency oscillation can be set up by a sudden change in the d.c. component of the picture signal; (c) that such damped oscillations can impair the quality of the received picture;

unanim ously decides that the following studies should be carried out: for the transmission of monochrome or colour television signals over a hypothetical reference circuit (2500 km): 1 . the maximum permissible amplitude of the damped very low frequency oscillations which can be set up by a sudden change or by periodic changes in the d.c. component of the picture signal;

2 . the methods of calculation which can be used to find the permissible amplitudes for circuits which have more or fewer sections than the hypothetical reference circuit; 3. the methods which may be employed to measure these damped oscillations and the distortions which they introduce.

STUDY PROGRAMME 1-1E/CMTT *

ALLOCATION OF TOLERANCES FOR COLOUR TELEVISION

The C.C.I.R., (1970)

CONSIDERING (a) that the subjective quality of colour television pictures is affected by the objective performance of every component part of an overall television system from picture source up to and including the receiver; (b) that the relationship between objective parameters of television signals and subjective assess ments of displayed picture quality is under study (Study Programme 14A/11);

unanim ously decides that the following studies should be carried out: the allocation of the specified total tolerances among the component parts of an overall television system from picture source up to and including the receiver, taking into account the statistical behaviour of departures from the nominal performance figures of the equipment.

* This Study Programme is identical to Study Programme IF/11. Q. 2-1/CMTT, S.P. 2-1A/CMTT — 306 —

QUESTION 2-1/CMTT *

REFERENCE CHAINS FOR TELEVISION

Application to real terrestrial chains longer than 2500 km and to chains including communication-satellite links

The C.C.I.R., (1970)

CONSIDERING (a) that, in some parts of the world, television transmission chains much longer than 2500 km and chains including communication-satellite links are either existing or under consideration; (b) that such chains may have many intermediate video connection points; (c) that it is desirable to define one or more reference chains corresponding to various typica connections and to determine the transmission performance of such reference chains;

unanim ously decides that the following question should be studied:

1 . what reference chain or chains should be defined, combining existing hypothetical reference circuits, for transmissions over distances substantially longer than 2500 km;

2 . are the definitions and transmission performance requirements of the existing terrestrial hypothetical reference circuit for television (2500 km, with two intermediate video points) and of the hypothetical reference circuit for a communication-satellite link, adequate to ensure satisfactory results on real chains; 3. if not, what additions or modifications should be made to the existing definitions?

Note. — A chain is a number of hypothetical reference circuits in tandem.

STUDY PROGRAMME 2-1A/CMTT

TELEVISION REFERENCE CHAINS FOR TERRESTRIAL AND COMMUNICATION-SATELLITE LINKS

The C.C.I.R., (1970)

CONSIDERING (a) that Recommendations 421-2 and 451-1 contain the definition and transmission performance of a terrestrial hypothetical reference circuit of 2500 km divided into three sections of equal length by two intermediate video points;

* This Question replaces Questions 2/CMTT and 3/CMTT. — 307 — S.P. 2-1A/CMTT, Q. 4-1/CMTT

(b) that Recommendations 352-1 and 354-1 contain respectively the definition and the transmission performance of a hypothetical reference circuit for a communication-satellite link comprising one Earth-satellite-Earth section; (c) that the characteristics of a communication-satellite link may differ from those of a terrestrial link and are not directly related to the great-circle distance between the earth stations; (d) that communication-satellite links may well be used to interconnect long terrestrial chains and that the resulting connections may include many intermediate video points; (e) that Annex IV to Recommendation 421-2 and the Annex to Part I of Recommendation 451-1 give guidance for estimating the characteristics of a chain when the characteristics of the individual link are known; '(f) that the concept of “reference chains” (see Note at end of Question 2-1/CMTT) of known composition would be very useful for determining the transmission performance to be recommended for the hypothetical reference circuits forming the chains; (g) that Opinion 38 applies to chains spanning countries with different television standards;

unanim ously decides that the following studies should be carried out:

1 . determination of the number of terrestrial and communication-satellite hypothetical reference circuits that should be included in reference chains corresponding to various types of links (e.g. intercontinental, regional, etc.);

2 . determination of the objective performance of reference chains consistent with the desirable subjective quality of the overall television system, from picture-signal source to receiver, for the various types of links;

3 . determination of the transmission performance to be recommended for the various types of hypothetical reference circuit, based on the desirable performance of reference chains; 4. method of calculation of the transmission performance of chains which do not contain the same number of terrestrial or communication-satellite circuits as the reference chains; 5. the possible inclusion of standard converters in the reference chains.

QUESTION 4-1/CMTT

DIFFERENCES IN TRANSMISSION TIME BETWEEN THE SOUND AND PICTURE COMPONENTS OF A TELEVISION SIGNAL

The C.C.I.R., (1963 - 1968 - 1970)

CONSIDERING

(a) that the time of transmission of television signals over a terrestrial or a communication- satellite system is generally not negligible; (b) that, if the sound and picture signals are transmitted by different methods or routes, there may be an error of timing between the sound and picture signals at the receiving end; Q. 4-1/CMTT, S.P. 4-1A-1/CMTT, 4-1B/CMTT — 308 —

unanim ously decides that the following question should be studied:

1 . what differences in transmission time can be accepted between the sound and picture com ponents of a television signal (see Note);

2 . what methods may be used to ensure that the acceptable differences in transmission time are not exceeded? Note. — A similar problem exists in connection with sound and picture recording on the same film (see Recommendation 265-2, § 3.2.2).

STUDY PROGRAMME 4-1A-1/CMTT

COORDINATION OF THE TRANSMISSION OF SOUND AND PICTURE SIGNALS

The C.C.I.R. (1966 - 1970)

unanim ously decides that studies should be carried out to determine:

1 . the authority which shall be responsible for making the necessary corrections in case the stipulated limits are exceeded; 2. the additional distortion that can be tolerated when such corrections are made by the Admin istration responsible for the programme circuit.

STUDY PROGRAMME 4-1B/CMTT

TRANSMISSION OF SOUND AND PICTURE SIGNALS BY TIME-DIVISION MULTIPLEX

The C.C.I.R., ‘ (1968 - 1970)

CONSIDERING i(a) that if the sound and picture components of a television signal are transmitted over different routes or by different methods there may be an error of timing between the signals at the receiving end; ,(b) that one method of minimizing this problem would be to transmit both signals over the same circuit by multiplexing; (c) that the study of systems of frequency multiplexing is associated with Question 3-1/9 and Question 18-1/10 and certain information related to these systems is contained in Recom mendation 402 and Reports 289-1 and 403-1;

unanim ously decides that the following studies should be carried out:

1 . techniques which can be used to enable a sound signal to be transmitted in time-division multiplex with the picture signal; 2 . standards of performance that can be obtained by the use of these techniques; S.P. 4-1B/CMTT, Q. 5-1/CMTT, S.P. 5-1A-1/CMTT — 309 —

3. special problems or requirements that might be introduced if these techniques were to be. adopted for the international transmission of sound and picture signals.

QUESTION 5-1/CMTT

TRANSMISSION OF SOUND PROGRAMME SIGNALS OVER LONG DISTANCES

The C.C.I.R., (1966 - 1970>

CONSIDERING (a) that the use of radio-relay systems and communication-satellite systems for the transmission of sound programme signals (whether accompanying a television signal or not) has become^ common practice; (b) that Study Group 9 is studying the transmission by radio-relay systems of one or more sound modulation channels with or without an accompanying signal; (c) that Recommendation 402, Report 289-1 and Report 290-1 on these subjects have already been published; (d) that so far as the quality of the sound-modulation channel is concerned, these texts are based on the C.C.I.T.T. standards for international sound-programme circuits; (e) that the C.C.I.T.T. is also studying ways and means of complying with these standards for a 2500-km hypothetical reference circuit on a cable system or over radio-relay links for telephony; (f) that new forms of radio broadcasting, in particular stereophonic radio broadcasting, have come into being since these standards were established; (g) that the C.C.I.T.T. standards for transmission by cable, particularly in respect of noise and crosstalk, cannot always be readily applied to radio-relay systems or communication- satellite systems; (h) that common standards for transmission are required in forms which are applicable to all methods of providing circuits;

unanim ously decides that the following question should be studied:

1 . what are the characteristics of the circuit and sound modulation signal to be considered, and what must be their values and tolerances if such transmission is to be satisfactory for the purpose of monophonic or stereophonic radio programmes; 2 . what methods of measurement and monitoring may be recommended ?

STUDY PROGRAMME 5-1 A-l/CMTT

CIRCUITS FOR HIGH QUALITY MONOPHONIC PROGRAMME TRANSMISSIONS

The C.C.I.R. (1966 - 1970)

unanim ously decides that the following studies should be carried out: 1. should Recommendations be established concerning circuits for monophonic programme transmissions of higher quality than those of type A circuits (Recommendation J.21 of the C.C.I.T.T.); S.P. 5-1 A-l/CMTT, 5-1B-1/CMTT — 310 —

2 . if so, determination of the general characteristics of such circuits (hypothetical reference circuit *, frequency band effectively transmitted, attenuation distortion, phase distortion, noise, intelligible crosstalk, variation of the relative level with time, non-linear distortion, error on frequency reconstitution, etc.). Note 1. — The C.C.I.F. has issued a Recommendation on this subject which is published in Volume III bis of the C.C.I.F. Yellow Book (Florence, 1951). Note 2. — Some Administrations have already received requests for setting up high-quality national circuits. C.C.I.T.T. Study Group XV considers that a study of this question is essential so that divergent technical solutions do not cause greater difficulties for international standardization. Note 3. — A reply to this Study Programme should enable C.C.I.T.T. Study Group XV to study a new question.

STUDY PROGRAMME 5-1B-1/CMTT

CIRCUITS FOR STEREOPHONIC PROGRAMME TRANSMISSIONS

The C.C.I.R., (1966 - 1970)

CONSIDERING (a) that the CMTT has embarked upon the study of circuit and sound modulation signal charac teristics to be recommended for the transmission of stereophonic broadcasting; (b) that it appears necessary for C.C.I.T.T. Study Group XV to study recommendations relative to the specification of the relevant circuit equipment; (c) that to enable C.C.I.T.T. Study Group XV to examine this question properly, the CMTT should inform it of the overall characteristics these circuits should possess;

unanim ously decides that the following studies should be carried out:

1 . hypothetical reference link *, frequency band effectively transmitted, attenuation distortion, phase distortion, noise, intelligible crosstalk, variation of the relative level with time, non linear distortion;

2 . whether there are any operating reasons for preferring one of the transmission methods mentioned below: 2.1 methods making use of two separate channels: either for the transmission of signals A and B respectively, or for the transmission of signals M and S ; 2.2 methods using a single wideband channel for the transmission of either signals A and B or signals M and S; 3. whether it is desirable that signals M and S be transmitted in a form identical with the signal modulating the broadcasting transmitter; 4. if the composite stereo signal is transmitted, what is the tolerable error in the reconstitution of the frequencies;

* The attention of the CMTT is drawn to Fig. 1 of Recommendation J.12 of the C.C.I.T.T. (White Book, Volume III) which can be compared with the first figure in Recommendation 421-2 (which is identical to Recommendation J.61 of the C.C.I.T.T.) for the purpose of drafting appropriate definitions. The definitions of the hypothetical reference circuit in Recommendation J.21 of the C.C.I.T.T. (White Book, Volume III) will probably have to be revised. S.P. 5-1B-1/CMTT, 5-1C-1/CMTT, 5-1D-1/CMTT — 311 —

5. if signals A and B are transmitted on a pair of channels constituting the stereophonic circuit, what are the acceptable differences between the characteristics of the two channels and what is the crosstalk attenuation required between channels A and J3? Note 1. — The list given in point 1 above is not exhaustive. Note 2. — C.C.I.R. Report 293-2 defines the general characteristics between the microphone and the listener, but does not specify what parts of the overall tolerances can be allocated to the programme circuit.

STUDY PROGRAMME 5-1C-1/CMTT

REVISION OF C.C.I.T.T. RECOMMENDATION J.21

The C.C.I.R. (1966 - 1970)

unanimously decides that the following studies should be carried out: amplification of the recommendations for type A programme circuits (C.C.I.T.T. Recom mendation J.21). Note. — The Report 492 contains a partial reply to this Study Programme.

STUDY PROGRAMME 5-1D-1/CMTT

CHARACTERISTICS OF SIGNALS SENT OVER MONOPHONIC AND STEREOPHONIC PROGRAMME CIRCUITS

The C.C.I.R. (1966 - 1970)

unanimously decides that the following studies should be carried out:

1 . determination of the characteristics of the test signals used by broadcasting authorities on programme circuits; any new types of test signals to be expected; Note. — The level of these test signals should be kept as low as possible to avoid overloading the amplifiers of the carrier system.

2 . the mean power (representative of usual broadcast programmes) of the signal applied at a point of zero relative level of a programme circuit, and the distribution of the “instantaneous” power levels corresponding to that mean power; 3. the mean power at a point of zero relative level (representative of usual broadcast programmes) of several signals, injected simultaneously into the same carrier system, and the distribution of the “instantaneous” power level corresponding to that mean power; S.P. 5-1D-1/CMTT, 5-1E-1/CMTT — 312 —

Note. — (applicable to 2. and 3.) Mention should be made of the characteristics of any studio limiters and/or compressors which have been used. In practice, the “instantaneous” values may be mean powers measured over a short period (e.g. milliseconds0. The type of measuring instrument should be stated. The instantaneous power level, which is exceeded with the probability of 10~5, is of particular interest because the carrier frequency systems are designed for an equivalent peak power (see Recommendation G.223 of the C.C.I.T.T.), which is equal to that power, which is exceeded with a probability of 1 0 ~5. 4. the influence on these values of any differences between methods and/or apparatus used for volume control (see C.C.I.R. Report 292-2); 5. the signals, other than normal broadcast programmes, which a programme circuit may be called upon to transmit. In particular the characteristics of monitoring and signalling tones used by the broadcasting authorities; Note. — Some broadcasting authorities transmit information which is used at the receiving end for monitoring the circuit performance. When the circuit is provided in a carrier system this information is in the form of audio-frequency signals at the upper edge of the band.

6 . the power distribution should be studied also after a limiter and/or compressor and/or a pre-emphasis network, if Administrations or broadcasting authorities use limiters and/or compandors and/or pre-emphasis networks; 7. the spectral power distribution of typical broadcast programmes and, in particular, the spectral power distribution of those parts of broadcast programmes which have a high pro portion of power at frequencies above 1 kHz.

STUDY PROGRAMME 5-1E-1/CMTT

COMPANDORS FOR PROGRAMME CIRCUITS

The C.C.I.R., (1970)

CONSIDERING

(a) that compandors may be used on programme transmission systems to give an improved noise performance; (b) that because of the many factors involved, it is not possible to draw any universally applicable conclusion about the tolerable amount of “expanded” noise from a compandored transmission system; (c) that it is not possible to lay down standard conditions, including experimental programme material, for a subjective test because the most critical type of programme depends on the type of compandor and character of the noise; (d) that it has not yet been possible to standardize compandors, but that such standardization would be very useful;

unanimously decides that the following studies should be carried out:

1 . the types of programme compandor which will be encountered on transmission systems; S.P. 5-1E-1/CMTT, 5-1G/CMTT, Q. 7/CMTT — 313 —

2. for a particular compandor, the maximum amount of noise of a given characteristic simulating circuit noise, as measured with the compandor absent, that may be tolerated with both a compandor and programme signal present. The types of circuit noise used should represent all types of noise which may occur on actual programme circuits; in particular impulsive noise, the subjective effect of which may be determined by the time constants used in the compandor. This mainly concerns those types of compandors which have a straight line compression characteristic down to Very low levels; 3. for a particular compandor, the variation of the loading of the line by the insertion of a compressor (with a pre-emphasis network if used). See also Study Programme 5-1D-1/CMTT; 4. for a particular compandor, the subjective and objective effects of up to three compandors connected in tandem; 5. for a particular compandor the effects in stereo transmission, if in each of the two channels there are installed up to three compandors.

STUDY PROGRAMME 5-1G/CMTT

TRANSMISSION OF SOUND PROGRAMME SIGNALS OYER COMMUNICATION-SATELLITE LINKS

The C.C.I.R., (1970) CONSIDERING that the use of communication-satellite links for the transmission of sound programme signals, and related auxiliary signals (whether accompanying a television signal or not) has become common practice;

unanimously decides that studies should be carried out to determine:

1 . the general characteristics of such sound programme circuits and, particularly, how these may differ from the characteristics specified for sound programme circuits provided by other means; 2. the general characteristics of circuits provided for the transmission of related auxiliary Signals, such as commentary, cue, control and engineering service circuits.

QUESTION 7/CMTT

AUTOMATIC MEASUREMENT AND MONITORING OF TELEVISION CHAINS

The C.C.I.R., (1970) CONSIDERING (a) that international television transmissions are becoming more and more frequent and that the distances covered are constantly increasing; Q. 7/CMTT, S.P. 7A/CMTT — 314 —

(b) that an efficient way to reduce impairments of the transmitted signal is to facilitate coordination between the operational services of the different telecommunications organizations concerned; (c) that, to this end, and taking account of present trends towards the automation of networks, the unification of methods of measurement and monitoring would be desirable; (d) that the introduction of automation in measurement and monitoring could increase the overall performance of long distance television chains and reduce the need for highly qualified maintenance staff;

unanimously decides that the following question should be studied:

1. what use can be made of test signal elements * for automatic measuring, monitoring and operation of networks; 2. what methods of analysis and processing are appropriate for automatic monitoring and operation of networks; 3. in what form should the results be expressed in order to facilitate the transmission or inter change of measurement and monitoring information; 4. what methods permit the comparison of the results of measurement data with the appropriate specifications ?

STUDY PROGRAMME 7A/CMTT **

AUTOMATIC REMOTE MONITORING OF TEST SIGNALS IN TELEVISION

The C.C.I.R., (1966 - 1970) CONSIDERING (a) that one method of automatic remote monitoring is based on the use of narrow-band pilot signals obtained, for example, by converting broadband information on the test signals into narrow-band information of the order of a few hertz (see Doc. 256, Geneva, 1963); (b) that with this method, a permanent record of the converted test signals can be obtained; (c) that the application of this method assumes the transmission of information obtained from the.test signals over telephone circuits;

unanimously decides that the following studies should be carried out:

1 . methods of automatic monitoring and control of television signals, for example, using the conversion of broadband information on test signals into narrow-band information, for pilot signals; 2 . the optimum conversion time of the test signals; 3. the recording equipment required for routine recording of the waveform and characteristics of the test signals for monochrome and colour television.

* The use of such test signal elements is referred to in Recommendation 473. ** This Study Programme replaces Study Programme 1A/CMTT. — 315 — S.P. 7B/CMTT, Q. 8/CMTT

STUDY PROGRAMME 7B/CMTT

AUTOMATIC MEASUREMENT AND MONITORING ON TELEVISION CHAINS

The C.C.I.R., (1970) CONSIDERING (a) that the amount and complexity of the monitoring and measuring equipment needed for the operation of television chains are constantly increasing; (b) that the qualifications of the staff required in consequence have to be extremely high; (c) that the merging of independent measuring facilities to form inter-linked systems and the presentation in discrete form of test signals and other characteristics to be monitored offer considerable scope for automation;

unanimously decides that the following studies should be carried out:

1 . determination of the chain or test-card characteristics that are measured or monitored which should be automatically indicated and/or recorded and the form of presentation that should be used (e.g. alphanumeric indicators, lamp indicators, printers, etc.);

2 . the characteristics which should automatically originate error signals and command read-out over the signalling system when they deviate beyond pre-set tolerances, and the way in which these signals can be used for technical diagnosis and forecasting of the operational performance of a television chain; 3. the form in which the deviations beyond pre-set tolerances should be detected; 4. the use of monitoring and measuring data for automatic control and optimization of television chain characteristics; 5. determination of the monitoring and measuring operations during the operation of television chains—including centralized monitoring and control of the television network—which should be carried out with analogue and digital computers; 6 . the methods and facilities which should be used with the computer to input, process and output the monitoring and measuring data relevant to the problem under study; 7. the additional requirements that should be specified for test and other special signals in connection with the questions listed in §§ 1 - 6 above.

QUESTION 8/CMTT

STANDARD TEST SIGNAL FOR CONVENTIONAL LOADING OF A TELEVISION CHANNEL

The C.C.I.R., (1970) CONSIDERING (a) that a common transmission path may be used by one or more television signals and one or more sound programme channels;

i Q. 8/CMTT, Op. 41 — 316 —

(b) that distortion occurring in the common path may cause unwanted signals to appear in the sound programme channels; (c) that Report 375 draws attention to the need for the television channel to be loaded with a standard test signal when measuring or calculating programme circuit noise; (d) that some test signals which may be used for the television circuit can cause substantial disturbance in a sound programme channel carried on a common path and that this might in some circumstances occur at times when the programme channel is in service;

unanimously decides that the following question should be studied: what characteristics for a special television test signal should be defined so that this signal can be used as a conventional load for television circuits when measuring, calculating or specifying the noise in a sound programme circuit carried in a common path with the tele vision circuit?

OPINION 41

BANDWIDTHS OF SOUND-PROGRAMME CIRCUITS

The C.C.I.R:, (1970) CONSIDERING that the views of the CMTT were sought by C.C.I.T.T. Study Group IV in Doc. CMTT/53 on two proposed classifications by bandwidth of programme circuits (see Doc. CMTT/53 which reproduces a C.C.I.T.T. document); IS UNANIMOUSLY OF THE OPINION

1 . , that its function is to draw up overall performance specifications for programme circuits of various nominal bandwidths but not to decide on what bandwidths should be chosen for such specifications or on their classification except for circuits of the highest quality;

2 . that the nominal bandwidth of a programme circuit should be defined as the band of fre quencies over which the performance is specified; 3. that a classification of programme circuits is necessary; 4. that the numbers of nominal bandwidths should be restricted as far as possible in order to limit the amount of work involved in arriving at specifications;

5 . the nominal bandwidths should be chosen taking due account of practicable methods of providing the circuits; it is recognized that while from the circuit user’s point of view it does not seem necessary to take account of the methods of providing circuits when choosing nominal bandwidths for classes of circuits, the economics of long-distance circuit provision will be strongly influenced by the relationship between the bandwidth of the programme circuit and the frequency allocation used for multi-channel telephone systems;

6 . that the chosen nominal bandwidths should be restricted to the following: — that corresponding to the highest quality (40 Hz—15 kHz) dealt with in Report 496; — a narrow bandwidth of about 100 Hz—5 kHz, to which the nearest corresponding specifications are contained in C.C.I.T.T. Recommendations J.31 and J.41 (6-4 kHz limit). Circuits of this nominal bandwidth should be the subject of further study;

t — 317-1 — Op. 41, Q. 9/CMTT

7. that consideration 'of this subject should continue with the cooperation of the broadcasting authorities.

QUESTION 9/CMTT

STUDY OF A DOMESTIC OR REGIONAL SATELLITE SYSTEM FOR TELECOMMUNICATIONS AND SOUND AND TELEVISION BROADCAST TRANSMISSION

The Plan Committee for Asia and Oceania, (1970)

CONSIDERING (a) that the costs of communication satellites and earth stations have greatly decreased during the past few years; (b) that the cost of leasing a large number of telephone and television channels from International Communication Satellite Systems for domestic or regional use may be uneconomical; (c) that the economic aspects of coaxial cable and radio-relay systems are being studied by C.C.I.T.T./C.C.I.R. Special Autonomous Working Party 3 (GAS 3), but comparable studies have not been carried out by the I.T.U. for communication-satellite system; (d) that a group of countries might share the cost on a regional basis;

requests the Director, C.C.I.R., to arrange for the study of the technical and economic aspects for a domestic and/or regional satellite system, which would provide good quality telecommunications, television and sound broadcast transmissions to meet the desired requirements. As far as possible the economic studies to be carried out should be in accordance with the methods indicated in the GAS 3 Manual. — 317-1 a —

QUESTION 10/CMTT

STANDARDS FOR TELEVISION SYSTEMS USING DIGITAL MODULATION

(1972)

The C.C.I.R.,

CONSIDERING

(c) that, to facilitate international exchanges of programmes and to rationalize the design of equipment, it would be desirable to standardize as far as possible the methods used for the digital coding of television signals;

(d) that digital signal processing, if used in television studios, could lead to improved reliability and performance;

decides that the following question should be studied:

1. what methods should be used for the digital coding of picture signals and the associated sound signals, and what would be the resulting advantages: — inside the studio complex, including the recording of television signals; — in the transmission of television signals on terrestrial channels using digital modulation; — in the transmission of television signals on satellite channels; — in direct broadcasting from satellites;

2. is there a single method of digital coding which would be suitable for all the uses described in § 1;

3. what digital standards should be recommended for the applications mentioned in § 1;

4. what is the simplest and most effective technique for monitoring digitally coded television and associated sound signals?

Addendum No. 2 to Volume V, part 2, Xllth P.A. of the C.C.I.R., New Delhi, 1970 — 318 —

QUESTION 11/CMTT

PERFORMANCE CHARACTERISTICS OF 5 kHz-TYPE SOUND PROGRAMME CIRCUITS

(1 9 7 2 ) The C.C.I.R.,

CONSIDERING

decides that the following question should be studied:

what should be the performance characteristics of a new type of sound programme circuit (designated by convention as “5 kHz-type sound programme circuit”) including the follow ing points:

1 . definition of the hypothetical reference circuit;

2 . nominal bandwidth and frequency band effectively transmitted; 3. permissible attenuation distortion; 4. permissible phase distortion; 5. permissible weighted and unweighted noise (with the definition of an appropriate weighting network);

6 . permissible intelligible crosstalk; 7. permissible variation in relative level with time;

8 . permissible non-linearity distortion; 9. permissible error on frequency reconstitution, etc.? Note 1. — Study Programme 5-1D-1/CMTT could be extended to include the effect of band width restriction. Note 2. — There may be two categories of use for such circuits, one for commentary purposes and the other also including transmission of music. If it seems advisable to recommend different characteristics for these two cases, this should be stated. Note 3. — Such circuits may be set up on carrier analogue systems and also on PCM systems; in the latter case, the permissible quantizing distortion should be stated. Note 4. — The CMTT should consider whether recommendations on intermodulation distortion should be given in addition to those on harmonic distortions. If so, how should the inter modulation distortion be measured?

Addendum No. 2 to Volume V, part 2, Xllth P.A. of the C.C.I.R., New Delhi, 1970 — 317 — OP. 41

7 . that consideration of this subject should continue with the cooperation of the broadcasting authorities. PRINTED IN SWITZERLAND