Transmission and decoding in colour television Citation for published version (APA): Davidse, J. (1964). Transmission and decoding in colour television. Technische Hogeschool Eindhoven. https://doi.org/10.6100/IR157915 DOI: 10.6100/IR157915 Document status and date: Published: 01/01/1964 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. 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If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, please follow below link for the End User Agreement: www.tue.nl/taverne Take down policy If you believe that this document breaches copyright please contact us at: [email protected] providing details and we will investigate your claim. Download date: 05. Oct. 2021 TRANSMISSION AND DECODING IN COLOUR TELEVISION J. DAVIDSE TRANSMISSION AND DECODING IN COLOUR TELEVISION PROEFSCHRIFT TER VERKRIJGING VAN DE GRAAD VAN DOCTOR IN DE TECHNISCHE WETENSCHAPPEN AAN DE TECHNISCHE HOGESCHOOL TE EINDHOVEN OP GEZAG VAN DE RECTOR MAGNIFICUS, DR. K. POSTHUMUS, HOOGLERAAR IN DE AFDELING DER SCHEIKUNDIGE TECHNOLOGIE, VOOR EEN COMMISSIE UIT DE SENAAT TE VERDEDIGEN OP DINSDAG 5 MEl 1964 DES NAMIDDAGS TE 4 UUR. DOOR JAN DAVIDSE GEBOREN TE WIERINGEN DIT PROEFSCHRIFT IS GOEDGEKEURD DOOR DE PROMOTOR PROF. IR. W. H. VAN ZOEST aan mijn vrouw CONTENTS INTRODUCTION . 6 1. GENERAL CONSIDERATIONS ON COLOUR TELEVISION AND TRANSMISSION . 7 1.1. Nature of the information to be transmitted in colour television 7 1.2. Basic principles of coding in colour television . 8 1.2.1. Physical and physiological foundations 8 1.2.1.1. Trichromaticity of colour vision 8 1.2.1.2. Appreciation of picture detail . 10 1.2.2. The constant-luminance principle . 12 1.2.3. Luminance and colour signals mixed highs 12 1.2.4. Coding of the chromaticity information 13 1.2.5. Gamma correction . 15 1.3. Transmission systems for colour television . 16 1.3.1. Introduction . 16 1.3.2. The NTSC system . 16 1.3.3. The SECAM system. 17 1.3.4. The FAM system . 19 1.3.5. Two-subcarrier systems 19 1.3.6. The Valensi system . 20 1.3.7. The system "double message" 20 1.3.8. Field-sequential and line-sequential systems 21 1.3.9. Final remarks on practical transmission systems 21 References . 21 2. INVESTIGATION OF THE FACTORS DETERMINING THE NATURE AND DESIGN OF THE TRANSMISSION SYSTEM . 23 2.1. General considerations on the method of working . 23 2.2. Unequal bandwidths for the chrominance channels in the NTSC system. 24 2.2.1. General design principles of the NTSC system . 24 2.2.2. Experimental investigation on the feasibility of equi-band operation of the NTSC system . 26 2.3. Experimental investigation on the consequences of bandwidth limiting in the chrominance channels . 28 2.3.1. Description of the experimental set-up . 28 2.3.2. Effects of bandwidth limiting . 30 2.3.3. Results of the experiments . 33 2.3.4. Review of experimental investigations described in the literature; comparison of results . 35 2- 2.4. Tritanopia of the eye for small objects as an explanation for the effects of bandwidth limiting . 38 2.4.1. Tritanopia of the eye for small objects . 38 2.4.2. Experimental investigation into the importance of small- object tritanopia for colour television transmission 40 2.5. Statistical con~iderations on colour television signals . 43 2.5.1. Introductory remarks . 43 2.5.2. Measurements on the average signal excursion of chromi- nance signals . 44 2.5.3. Determination of statistically optimum coding axes . 46 2.5.4. Subjective experiment concerning optimum choice of coding axes. 47 2.6. Crosstalk phenomena in band-shared transmission systems . 49 2.6.1. Crosstalk of the chrominance signal into the luminance channel . 49 2.6.1. 1. General considerations . 49 2.6.1.2. Experiments . 50 2.6.2. Crosstalk of the luminance signal into the chrominance channel . 52 2.6.2.1. Introduction . 52 2.6.2.2. Experiments . 52 2.6.2.3. Results of the experiments. 53 2.6.2.4. Theoretical analysis of the crosstalk phenomenon 54 2.6.2.5. Conclusions . 60 2.6.3. Crosstalk between the chrominance signals . 61 2.7. Comparison of transmission systems as information-handling media . 61 2.8. Methods of gamma correction and constant-luminance errors. 63 2.8.1. General considerations; survey of the existing literature 63 2.8.2. Statistical approach to constant-luminance errors . 67 2.8.2.1. Need for statistical data on colour saturation 67 2.8.2.2. Measurements on subcarrier level distribution 67 2.8.2.3. Evaluation of the measuring results; Conclusions on gamma correction and constant-. luminance errors . 70 2.9. Noise and interference in the transmission system 72 2.10. Imperfections of the transmission path. 75 2.11. Ease of decoding the transmitted signal 77 2.12. Compatibility of the colour television signal 78 2.13. Modifications of the basic transmission systems 80 2.13.1. Introductory remarks . 80 2.13.2. Modifications of the NTSC system . 81 -3- 2.13.2.1. Adaptation of the subcarrier signal to one-gun decoding . 81 2.13.2.2. Circular subcarrier signal . 81 2.13.2.3. Enhancement of single-sideband components of the subcarrier signal . 81 2.13.2.4. Signal-controlled encoding . 82 2.13.2.5. Colour phase alternation . 82 2.13.3. Modifications of the SECAM system . 84 2.13.4. Modifications of the FAM system . 85 2.14.General comparison of transmission systems; conclusions 85 References . 87 3. INVESTIGATIONS ON DECODING IN COLOUR TELEVISION 90 3.1. Introduction . 90 3.2. Essential elements of the decoding system . 91 3.2.1. Filtering of the chrominance signals. 91 3.2.2. Decoding with sequential display devices . 93 3.2.2.1. Three-gun and one-gun decoding systems . 93 3.2.2.2. Basic principles of one-gun display tubes . 94 3.2.2.3. Formulations of the driving signal for one-gun tubes. 95 3.2.2.4. Analysis of the mechanism of self-decoding in one- gun tubes. 96 3.2.2.5. Mathematical analysis of one-gun decoding errors 99 3.3. Decoding circuits for one-gun display tubes 103 3.3.1. General theory of signal translators . 103 3.3.2. Simplified signal translator circuit . 106 3.4. Modification of the transmitted signal for simplifying one-gun detection . 107 3.4.1. Can a one-gun tube be devised needing the NTSC signal as the driving signal?. 107 3.4.2. Modification of certain design parameters of the transmis- sion system . 109 3.4.2.1. Modification of primary colours and choice of reference white. 109 3.4.2.2. Modification of the subcarrier signal . 110 3.4.2.3. Choice of the /-and Q-signals in the modified sub­ carrier signal . 112 3.4.2.4. Constant-luminance errors with the modified signal . 113 3.5. Utilization of the vestigial-sideband components of the /-signal 115 3.5.1. Introduction . 115 4 3.5.2. Practical methods for utilizing the vestigial sideband infor- mation. 115 3.5.3. Analysis of the two-mixer circuit . 117 3.5.4. Application to one-gun display systems... 119 3.5.5. Incorporation of Y-to-M conversion in the two-mixer cir- cuit . 123 3.6. Compensation of luminance errors . 125 3.6.1. Introduction . 125 3.6.2. Analysis of the luminance errors 125 3.6.3. Possible practical methods of luminance correction 128 3.6.3.1. Addition of a correction signal to the luminance signal . 128 3.6.3.2. Luminance correction by controlled amplification of the "mixed highs" . 130 3.6.3.3. Luminance correction employing the existing crosstalk of the subcarrier into the luminance channel. 131 3.6.3.4. Luminance correction by the addition of a differ- entiated subcarrier signal 136 3.6.3.5. Final remarks . 140 References. 140 4. DECODING WITH BEAM-INDEX DISPLAY TUBES 142 4.1. Introduction . 142 4.2. Basic principles of beam-index display tubes . 142 4.3. Conversion of subcarrier modulation to writing frequency 144 4.4. Stability of the index loop . 144 4.4.1. General considerations . 144 4.4.2. Use of high-frequency pilot carrier. 145 4.4.3. Particular problems of secondary-emission indexing . 146 4.4.4. Employment of separate pilot beam .