For British Telecom staff only Contents

Editor: Ron Quinney (LES4.2.4) Editorial Published by IDHO/LES4.2.4, Microphonic noise in Strowger exchanges 1 Room 301 , MAC- recognising unrecognisables 3 203 High Holborn LONDON WC1V 7B U Building serv1ces- control for the 80's 5 01-432 2806 A man's home is his ...college 7 NITE shift- new tariff equipment 9 Maintenance News Under carpet cable for office Telecom systems 11 Operations and maintenance centres (OMC) 15 TXE 4: Present performance and future Targets 18 The Ambassador Electronic Switching System (ESS) 20 New housings for Public Call Offices (PCO) 22 Lightning protection of modern equipment 24 KILOSTREAM- Fault handling procedures 26 Computer maintenance in British Telecom 29 Maintenance News aims to provide a medium Progress on implementing the Repair for two-way communication - that is, between Service Strategy 31 Headquarters and the field . If you want to write Microfiche documentation for TXE 4 32 about anything you may have seen in Maintenance News, or indeed, about any Ernie's to blame 33 maintenance topic. send your letter to: The Telegraph Transmission- 'SCVF IN : 80V Editor, Maintenance News. Room 301, 203 0~ ~ High Holborn, London WC1V 7BU. Say what On reflection 37 you like, but the Editor may tone comments Letters 37 down if he decides to publish. Do please give Index 39 your full address. ·

Produced by CRD/Management Communications Editorial Mierophonie noise in StroUJeer e~ehanees

One of the gratifying things about being the by Rob Goundry BTM/SM3.1 the improving performance of the network editor of a magazine such as this is that people Microphonic noise- the name given to brought about by modernisation, rather than any actually read 1tl What is more, they get very electrical noise caused by mechanical widespread slipping of maintenance standards. upset if they do not receive their own copies. vibration - has always been a problem 1n In this new environment Strowger can 'sound' Fortunately, in spite of the two Strowger exchanges where the connection comparatively poor- a fact frequently brought reorganisations of HO smce Maintenance News from one customer to another is dependent on to our customers' attention by radio phone-in emerged as a medium for Service Department, the sliding metal contact between wipers and programme presenters. Although the number of the powers that be have continued to banks, open relay contacts, 'u'-points, and the calls broadcast on radio is very small, an acknowledge the value of this magazine. like. All of these contacts are subject to the audience of several millions hears the DJ Personally, I feel MN will play an even greater ravages of atmospheric pollution, airborne dust complain of another 'poor line'. This is a role with the impending demise of Tis. Already particles and quite severe vibration when significant factor in forming and establishing our we are seeing 'newsy' items appearing in MN selectors step, hunt and release. That the customers' opinion of our service. Noise levels which otherwise which might have been printed system works as well as it does, is a credit to that were tolerable 40 years ago- when 2000- in Tl format, and distributed to many those in the past who specified, designed and type switches were designed- are becoming Inappropriate files- a point brought out by Brian built it and all those now involved in its less acceptable in the 1980s; not only to voice Grover in this issue's On Reflection. maintenance. The system designers did their services but also for data traffic. Noise during To return to my starting point, we try to make job thoroughly. Reports in our files detail tests data transmission can corrupt information and, if MN as readable- and as accurate- as possible. using a wide range of different wiper and bank it occurs frequently, results in the need for Points on which your editor has been taken to contact surface metals including gold, stainless proprietary error-correcting equipment. Thus task- on abbreviations by one correspondent, steel and rhodium. Wipers with oil damping to some of our more important customers can lose and by an observant reader (obviously an RSC reduce vibration were tried, and even the use of confidence in our services and may be put to man) who pointed out that the photo on page 29 PTFE as a wiper/bank contact 'lubricant' was extra expense. Our customers' sensitivity to was printed in reverse I investigated. The materials chosen as standards faint and noisy calls is very evident in initial Distribution errors do occur, I'm sorry to say, by our predecessors were a compromise results from TELCARE- Telephone Customer but it would assist me if queries could first be between the purchase price and the cost to Attitude REsearch, the scheme in which our made to local distribution duties, as they can maintain a given standard of service over a long customers are asked in a telephone interview to often sort things out. There are always enough life. comment on our services. Figures for both local copies to go round. and trunk service indicate that many customers -Editor Why the interest now7 have difficulty hearing or being heard because of Few changes have been made to the design of faint or noisy transmission, and this is clearly a 2-motion switches over the years, so why is cause for concern. noise in Strowger exchanges now looked on as a growing problem? The most likely reason is - Noise sources Solution we would like- and noise will arise randomly What are the sources of microphonic no1se 1n a Implementing schemes to reduce no1se is from items such as line relay contacts which are Strowger exchange 7 Banks and wipers clearly a formidable task- given that there are not subject to regular routines. It is inevitable immediately come to mind, but there are quite a over a million 2-motion switches still in service. therefore, that some switches will become few other common causes- as listed in At this late stage in the life of Strowger most prone to noise. The task for maintenance staff Tl E6 0 0014- and summansed here: ideas are not economically viable, although the then becomes one of minimising the number of • Line wipers- dirty or having excess1ve tip recently published change to w1per tip gap such switches without taking too much effort wear and gap. adjustment limits is a notable exception. Wiper from preventive work. Some automatic • Line switching relay contacts- lack of tension tip gaps should now be set in the range 14-18 assistance in locating those noisy switches and block lift, or dirty. mils. Th1s means that the adjustment range has would be useful, but all previous attempts at • Line bank contacts- dirty or tarnished. been tightened up by 2 mils at each end. This designing a practicable and economically viable • Line wiper cords- h1gh resistance approach should result in the same 16 mils add-on "noise detector" for routiners/call terminations and suspect continuity. average tip gap as before, so avoiding any senders have been unsuccessful. An earlier • 'U'-points- dirty or tarnished contacts, depth poss1ble bank wear problems that may have article (MN6 p24) recorded the outcome of a of engagement inadequate arisen if only the top limit had been changed A major effort in this direction between 1968 and • Selector seating- Incorrect alignment with w1re gauge- Gauges Feeler No 35 (item code 197 4. On a much more positive note, we now bank, loose cradle/rack shelf cross-member 14 1683 in Section 5TB of the vocabulary of have MAC- the system of Measurement and screws. stores)- is available to enable checking of the Analysis Centres (see MN21)- to help us. • Selector covers- in contact w1th adjacent new adjustment. This tool has both 14 and 18 MAC tone detection and identification is covers thereby transmitting vibration. mil gauge wires projecting from the same end, achieved by a combination of 400Hz and • Wiring- spurious connections between the thereby making the jOb a little less tedious than 1OOOHz tone detectors providing inputs to the circuit and frame. with the 12/20 gauge. The new adjustment will MAC processor. There the program enables the take a full routine cycle of three years or so to tone presented to be identified by its cadence. Prevention better then cure become applicable to all switches. The resulting Although tolerant of noise in both detection and Recent investigations in several parts of the (hoped for) reduction in noise will therefore be identification, MAC will not resolve a tone in the country have confirmed that there 1s no quick progressive Re-bladed wipers from Piece-parts face of severe no1se on the line. In such cases, and easy way to reduce noise. Know1ng the depot (PPD) will shortly be supplied adjusted to MAC is likely to record the call as a plant defect common causes helps to locate faults - but the revised limits, and adjustment of new in the 'unrecognisable result' (UR) category. prevention 1s better than cure. This is largely a wipers is being pursued with the MAC 'UR' results can therefore be looked on as matter of keeping the switches 1n good manufacturers. It is worth mentioning that we a rough measure of the incidence of 'no1sy' condition by routine maintenance. The would not have to buy new wipers if sufficient calls. In the case of MS1 (measurement frequency of routine work can best be assessed were returned for refurbishment- so keep sequence 1, own exchange test calls) this is a locally in the light of expenence with a particular those old w1pers rolling in to PPOl measure of noise for individual exchanges. It exchange. In practice it is not always possible to can only be a 'rough measure' as some noisy complete preventive maintenance as often as calls will not affect MAC at all. and others can be

2 MAC-reeognising unreeognisallles

classified as UR for reasons other than noise. by Bill Collins LES4.1 .2 Tone recognition on MAC is carried out in two The following article "Recognising the Measurement and Analysis Centres (MACs) are stages- unrecognisables" gives more detail on the MAC now installed in all Areas to measure the quality • Hardware: TNT and supervisory tones are tone identification system and describes some of service given by the public switched received by filters in the special interface of the more common causes of URs. telephone network (PSTN). Patterns of test calls hardware (SIH) at the MAC centre and are made on various parts of the network and reported to the processor using on/off delay A quiet life the results of these calls are recorded and used timers. These timers prevent transient As the network becomes progressively quieter to compile performance statistics for interference conditions from being reported to with the provision of modern switching and exchanges, Areas, Regions, and so on. Detailed the processor. transmiSSIOn systems, pressure to keep fault information is also available to exchange 1004Hz tone (which is part of MAC TNT) is Strowger quiet will increase. maintenance staff including, for example, detected by a narrow-band filter and has So be aware of the importance of individual failure files (IFFs), and analysis transmission tests carried out on it with microphonic noise: sequence results, which can be obtained as selected calls- about 1 in 20 of all calls • its causes required from the local MAC staff. generated by the MAC. • the need to prevent and cure it To carry out these measurements the MAC 400Hz tone is detected by a broad-band filter • the use of MAC to indicate its incidence and processor must be capable of identifying calls with a frequency response of 300 to 500Hz. • the use of MAC analysis sequences to assist that successfully receive test number tone This broad band is necessary because of the in locating it. (TNT) from answering equipments used by wide frequency vanation on 400Hz Most of our customers would be satisfied MAC, or that receive a supervisory tone, such as supervisory tones and ordinary TNT (not-MAC with a quiet life, so let's make sure they get busy tone, number unobtainable tone, and such generated) found in the network. one- well, at least from your Strowger like. • Software: Outputs from the filters and delay exchanges I A combination of hardware and software timers are recorded in software by the design is used by the processor to decode these processor during a 6-second tone decode Strowger Regional Service Improvement Centre various tones and record them under their period, known as the 'seek match' period. - a national service provided by correct categories. But if the tones or conditions This seek match period is compared against a BT Midlands HQ received on a call cannot be identified, the result cadence table- specified in software- of all (021 643 5048) of that call is recorded as 'Unrecognisable' (UR). categories of tones that the MAC is required A brief description follows of how the processor, to detect. The table takes into account the defines a UR and of various causes found for timing tolerances to be found on the various UR's in the network. tone supplies. If the tone durat1ons recorded in the seek match period fall within the tolerances of a tone category specified in the cadence table, then the result of that call will - 3 be recorded under that category, for example DDouble switching to conversation - found designed to respond down to -35dBm as busy tone, ring tone, test tone. and so on. to be a main cause of URs. The broad~band measured at the access equipment exchange However, if the seek match period does not 400Hz filter, referred to earlier. will detect outlets). compare with any of the categories in the speech frequencies within its band and cause Low frequency interference faults on cadence table, the processor records the random speech~induced outputs to the exchange power supplies have also caused URs result of that call as 'unrecognisable' (UR) In processor. The processor will be unable to during MAC tone detection. These are now other words the processor has received a call identify these as a legitimate result and will identified by routine noise tests carried out by result that falls outside all known parameters therefore record a UR. the centre staff who arrange for any faults to be for TNT and supervisory tone supplies and DNoise- another main cause of URs- was cleared. therefore cannot identify it. proved to bank and wiper noise on Strowger DMAC equipment exchanges. although other causes were found During the implementation phase of MAC it was Causes found for UR's on all exchange types. for example high found that the processor was not tolerant As plant defects- such as number unobtainable resistance (H R) connections, faulty spring~sets. enough of short duration switching noise. This (NU), no tone (NT). or ring tone (RT)- were faults on crossbar switch fingers. and so on. has now been improved while ensuring that gradually improved in exchanges due to action The 400Hz filter will detect noise (which has double switching (speech) faults are still taken on MAC results, with some exchanges it frequencies within its response band) and cause detected. Other minor system interworking was noticed that there was no corresponding spurious outputs to the processor. similar to problems also came to light. which have been improvement in the level of UR failures. In fact. that described above. However. the processor cleared by software modifications. with some exchanges the URs appeared to get is tolerant of short duration noise and only if the By the time this article is published the most worse. Although a possible explanation for this noise is loud and long enough in duration will the up~to~date tone recognition software will have was that as the other faults were cleared, URs call fail as UR. Subjective tests have been been proved and loaded on all MACs. were being revealed, it was necessary to carried out to set the tolerance at such a level identify the causes of these URs. that only noise considered to be unacceptable Identifying URs Inland Division's MAC Operations Group and on a customer's call will lead to a UR, which is It is not possible to determine retrospectively MAC staff in various Regions and Areas. carried the correct result. the reason why a particular call has f.ailed as UR. out special investigations to find out the causes (The previous article in this issue deals with Th1s is because the processor cannot record the for specific UR failures and to check that the causes of switching noise on Strowger difference between such obscure failures as processor handling of tone recognition was exchanges.) faulty tone supplies. and noise and speech correct. DMiscellaneous tone supply and network frequencies ringing on the MAC filters, for The results of these investigations showed faults were proved to out~of~tolerance ringing example. It is therefore necessary, if the UR that there was no single cause for UR failures, machines. tone supplies in contact. faulty PCM failures on an individual exchange are relat1vely but they could, in fact. be divided into a number channels, and excessive 400Hz attenuation in high, to carry out a special investigation to of main fault headings- the network. (The MAC tone detectors are determine the causes for specific URs. 4 Building serviees­ eontrol for the 8o's

Experience to date has shown that a high failure by Mark Hindley ETA5.2.1 remote sites. The printer can also print out data rate on an exchange will usually prove to be in The continuing increase in energy costs and at timed intervals or when plant is switched on one of the mam fault categories referred to the environmental needs of current telecoms or off. earlier. equipment, make accurate and effective At each remote building are a number of data It is recommended that UR spec1al control of building services equipment gathering panels (DGPs) which are connected to Investigations are carried out with the essential. One method of improving control existing plants to collect information and allow assistance of the local MAC staff. They have the is by the use of a 'Centralised Control and control as required. The DGPs convert necessary information and facilities available to Monitoring System' (CCMS). information into digital form and send it through adv1se on the best approach. For 1nstance they The benefits of the system are closer control, a transmission loop and datellinks to the CPU. have up~to~date failure patterns, additional call more effective use of energy and better Any control commands issued by the CPU are sendmg fac1lit1es (AS2), special test programs maintenance. To gain expenence of this type of transmitted by the same method to the DGP and the expenence of dealing with similar control system a field trial, involving 17 which interprets the command and operates problems on other exchanges in the Area. buildings, is under way in Leicester Telephone plant accordingly. Each DGP can be used for up So if you are havmg diff1culty in getting to Area. to seven control functions and 20 monitoring grips w1th URson your exchange, you are As outlined in figure 1. the basic concept of points. advised to have a word w1th your MAC staff to the CCMS is to collect mformation on ident1fy the causes. conditions, plant status and alarms in remote Monitoring All staff involved with the operation of MACs buildings and transfer this information to a The CCMS allows constant monitoring of at IDHO. Regions and Areas. constantly monitor central control for processing. The information building temperature, humidity; energy usage; the performance of the MAC. If any changes or can be used for monitoring purposes. or it can plant status (on, off); and alarms. This is improvements are considered necessary they be used in programs to control the operation of achieved by using suitable sensors or relays or, are implemented speedily to ensure that the plants in the remote buildings. in the case of electricity and gas consumption, MAC continues to give a reliable and accurate Situated at the control centre in Leicester by using specially fitted meters. giving a pulse measurement of the service given by the PSTN. (Cardinal) exchange is a central processor unit output related to consumption. This information, This also ensures that failures are quickly (CPU) with associated visual display unit (VDU), coupled with the control capability, allows close brought to the attention of maintenance staff operator keyboard and printer. Information is control of building conditions and accurate who have to find and clear the faults. displayed by the VDU and printer either by monitoring of when and where energy is being (0 1~432 207 4) request, or automatically in the case of alarms. used. In addition, the immediate notification of The operator can request further information, to any alarms results in a faster response to faults. analyse a situation, and control plant by use of reducing out~of~service time and consequent the keyboard. The VDU and keyboard are also problems with telecoms equipment and staff used to program the system to react discomfort. Information on plant running times automatically to changes in cond1tion at the can be used to automatically indicate when - 5 F1gure 1. Typical Centralised Control and Monitormg System Remote Digital Sensing Data Collection Transmission Processing Operating Interface

To other RDPs in To other same building remote buildings Local Sensors and Controllers

Graphic Projector

Modem Modem c

REMOTE BUILDINGS • • p ------~------~------~--- LOCAL BUILDINGS u VDU

Local Sensors and Controllers

ll L To other Local Pnnter/Keyboard Sensors buildings and Controllers Security MEMORY Control Panel

To other RDPs in Alpha Numeric Display/Keyboard same building

6 A naan's honae is his .. eollege maintenance is requ1red- avo1ding Dt1me control programs are used to control rack by Richard Harris BTTC/IT7.3.8 unnecessary routines. lighting in exchanges, security lighting at Many potential students who wish to attend Telecom engineering centres (TECs), further education courses leading to Control domestic hot water services and other Technician Education Council (TEC) or There are three types of control program equipment benefitting from time-related Scottish Technical Education Council available- control. (SCOTEC) awards, find that getting to a • Standard Control program college on a regular basis presents a • Control Interpreter Language (CIL) program Fire and security problem. This may be due to geographical • Time Control program The CCMS also provides automatic f1re and difficulties, circumstances in the home, or Dstandard control programs are those supplied security monitoring systems. The building even working limitations such as shiftwork. w1th the system and cover such thmgs as security package includes automatic building On the other hand it may be that their local optimum start control for heating systems; access control for entrance doors, timed report college is unable to offer the course they maximum demand control of electrical facilities for security teams and, a recent require. supplies; and duty cycling control for addition, closed circuit tv capabilities. External Student Scheme ventilation and air cond1tion1ng systems. To meet the needs of these students a scheme These programs are ready for use and will Benefits has been developed to enable them to study at control plants automatically once the The CCMS facilities allow a complete build1ng home, and at times to suit themselves. This necessary equipment information and control management system to be provided. This can scheme, known as the External Students parameters are entered. control all of the main functions of one or many Scheme (ESS), uses learning packages, and is DCIL programs are tailor-made to suit a buildings. The system not only improves run in co-operation with 35 participating particular control need: they are written and environmental control, plant performance and colleges. entered by the system operator. They allow building security, but also ensures considerable complex or unusual control problems to be savings in energy and maintenance costs. Learning packages overcome and Introduce a flexib1l1ty that (0533 29896) Each learning package is written to the allows the system to be developed in an objectives of a TEC/SCOTEC approved syllabus innovative way. These programs are used to and therefore contains all the information control boiler firing rates, selection of heating students need to succeed in their course of stages, with reference to outside air study. It is similar to a correspondence course in temperature, control of heating zone valves, that students are their own masters, choosing with reference to room temperatures; control when and where they wish to study. However, of ventilation and air cond1t1oning for staff in the case of the learning packages, students comfort during occupation. and equ1pment are allocated a tutor to guide them through their protect1on at other times. course. -7 assessment questions are provided to enable students to test for themselves how well they have understood that particular part of the course. The student rece1ves the learning package 1n three separate 1ssues, each with homework which IS submitted to the tutor for mark1ng. Applying for a course Students wish1ng to take advantage of the scheme must apply through their Area Tra1ning Off1cer (ATO) who vets the applications to ensure that this IS the most suit9ble mode of study. The ATO then adv1ses on the course that best su1ts the student's needs, arranges enrolment with a college that part1c1pates 1n the scheme, and forwards the papers on to Harrogate for processing. The college selects the tutors and deals w1th the general administration. If a college 1s not available, the scheme IS wholly administered by BT who will also arrange independent tutors. The tutor's role The tutor gu1des the student through the course, markmg homework and holding 'face-to­ face' tutonals, during wh1ch advice is given and Example of learning package difficulties explained. A tutor may also be available at pre-arranged times for students to seek help by telephone. At present there are eighteen subjects A learning package is divided into sections, At any stage of the year the tutor can arrange covered at levels 1, 2 and 3. The packages, each of which consists of a number of for a student to attend a 'remedial' tutorial which are the result of years of careful product convenient working un1ts- known as should homework 1nd1cate a student IS in design, are written at the BTTC, Stone, by a segments. Each segment 1s a lesson 1n itself difficulty. These may take place during the day team of specially-trained authors. The and is designed to take approximately one hour or evening and are organised in conjunction w1th administration, illustrations, printing and to study. Some of the segments include audio the student's superv1sing officer. distribution are undertaken by BT's Harrogate­ cassettes which are particularly useful for based reprograph1c serv1ces group 1n co­ dem0nstrating such things as tones, or the Assessing performance operation with the Old Street Illustration Studios effect of restricting bandwidth on frequency During the year, at levels 1 and 2, students in London. response. At the end of each segment self- undertake in-course tests- known as phase 8 tests- followed by an end of un1t test. These There were very few cancellations and tests are prepared by the authors at Stone and withdrawals at either level. NITEshift moderated by TEC before use, although Policy colleges may use their own assessment The policy is set by IDHO/IT5 in London, who material1f they so wish. The tests are invigilated The Introduction of a New International Tariff co-ordinate the scheme with Regions/Boards locally and held e1ther at the student's Equipment (NITE) and the TEC. They also monitor the nominated college, or at a centre close to his by Bob Stroud LES 4.1 .1 performance of external students to produce place of work. At level 3, special homework The need for improved flexibility in the charging national statistics and to develop policies which assignments are used in place of the phase of customer dialled calls is of importance to best meet both students' and BT's business tests. British Telecom in a competitive environment interests. After marking, the tutor sends the results To meet part of this need a replacement tariff (which may include guidance) to the student. In The path ahead equipment has been developed and is being the event of a borderline result the papers are • BT is confident that the scheme has all the installed at all exchanges concerned with the examined by a TEC moderator who, taking into qualities to justify it being regarded as a model generation of tariff pulses for the charging of account the student's homework and tutor's for wider national application. Learning international calls. recommendations, gives the final decision on packages are being purchased by an the student's result. increasing number of college lecturers for use Old and new The ESS has to allow for a number of as a guide on the depth and standard of their The obsolescent equipment consists of differences between the TEC and SCOTEC own tuition. Machines Pulsing 23A and Tariff Control Rack administrations. For example, TEC is not an • The revision of the City & Guilds (AT 5525) The Tariff Pulse Distribution (TPD) examining body and the course assessment is Telecommunication Technician Scheme, 1n racks are being retained and modified for set by the colleges. or BT, w1th the overall result which substantial TEC material has been distribution of pulses from the new equipment being dependant on the results from all the adopted, will make a number of the existing The new International Tariff Equipment phase tests and the end test With SCOTEC learning packages suitable for overseas Control Rack (ITECR) consists of however, it is their end examination, similar to students studying C & G courses. microprocessor-controlled Equipment Pulse the former City and Guilds examination, that • Taking advantage of modern technology, a Generating 3A (EPG 3A) and Equipment determines the grade awarded to the student A method of providing tutorial facilities between Distribution 1A (ED1 A). TEC student may be awarded a fail. pass, pass tutors and remotely-situated students is with merit or distinction, while the SCOTEC undergoing tnal in Aberdeen North. Known as Equipment student is graded from 1 to 10. Cyclops, it is a two-way electronic blackboard The NITE is a pulse generating system linked by an ordinary telephone line, and saves composed of two asynchronous generating The record of success tutors and students from having to make long sections operating in a main/standby mode. An analysis of the results achieved in 1980/81 and time-consuming Journeys to tutorials. Yet Each section consists of an EPG3A and, indicates a remarkable success rate for the another example of distant learning, and, one depending upon the load imposed by the call scheme. Over 6000 packages were distributed step closer to taking the classroom into the timing equipment (see Loading), one or two from which the results were . student's home. shelves of 15 short 62-type Pulse Distribution Level 1 74% successful (0785 762690) Units (PDU) Level 2 ...... 72% successful Provision is made for connection of pulses from one section at any given time. This, and- 9 Pulses Alarms EPG3A PDUs Pulses A A Monitor Alarms & supy's numbered racks. Where the 1OA sourcing Pulse connect A capability is insufficient to meet the demand 1mposed by the call tim1ng equipment, a second COM.S. Alarms C/0 . A Puis es distribution equipment (Auxiliary ED1 A) is UNIT UNIT Connect mon1tor B r--- to TPD rack Alarms & supy's provided. The outputs (2 x 5A) from each PDU are commoned and, typically, outputs from the Pulse connect D first ED1 A (Main) serve odd numbered racks, Alarms outputs from the second (auxiliary) ED1A serve & supy's even numbered racks. Monitor Facilities EPG3A PDUs The EPG3A can deliver up to 15 pulse supplies B B Alarm each at four different charging rates. Any one of Pulses 64 available day programmes (tariff patterns) Figure 1. International Tariff Control Equipment ('A' on line) may be allocated on a 24-hour bas1s to any pulse supply or supplies. Each day programme allows pulse monitoring of both generating sections, is programmable read-only memory (EEPROM) is up to eight rate changes per day wh1ch may controlled by a changeover unit (c/o.u) uDder sent to the EPG's associated Pulse Distribution occur on the hour or half-hour. Pulse rates may instructions given by the EPGs. Alarms are Units (PDUs) under control of the be selected from the range 600ms to 60 initiated by a Common Services Unit (COMS.U) microprocessors. seconds at 50ms intervals. which acts upon instructions given by the EPGs Each of the EPG's associated PDUs convert Spec1al day programmes required to operate or C/0 unit earth pulses into two battery pulse outputs to for one day, such as the changeover from GMT­ An explanatory diagram of the system is the TPD rack. BST, cheap rates for bank holiday and so on, shown in figure 1. The EPG3A's in-built 'watchdog' and may be pre-programmed from the EPG3A's 'checksum' circuits provide hardware and keyboard. Pulse generation and distribution software checks to ensure the tariff information The EPG3A contains a 5MHz crystal oscillator being sent is valid. Tariff changes (10MHz-7-2) for its timebase. The As previously mentioned, tariff information IS microprocessor, which can be Instructed from a Loading held in a fixed memory dev1ce known as an keyboard to gate information to an LED display, Each PDU is capable of sourcing up to 1OA per EEPROM Each s1te where NITE is installed has operates under the control of the execut1ve supply (2 x 5A outputs). Typically, for each of 15 been provided with a programmer in order to program held in EPROM. Tariff information, supplies available, output 1 serves odd implement tariff changes detailed 1n NPDTE which is held in an electrically erasable numbered racks and output 2 serves even series work specifications. 10 Under earpet eallle for offiee Teleeo111 s~ste111s

History and further developments by Alan George BTN E/S32 The need NITE is a furtherance of the EPG 1A and EPG2A Mention 'block wiring' to either installation Traditionally, new buildings are constructed with projects which were to provide small or maintenance staff, and it conjures up a cast-in-situ concrete floor slabs, finished with a exchanges- UAX's for example, previously vision of distribution cabling terminated on fine screed providing a smooth and level floor dependent on wire broadcast (WB) links, from boxes connection with masses of flexibility which easily accommodates trunking and parent GSC's- with their own local tariff jumpers, non-existent records, floor trunking conduits for telephone and electrical wiring. But equipment. Replacement of STD tariff or conduit which never goes where it is the building industry- looking for means of equipment has been discussed, but no decision needed, trailing cords and so on. Our staff reducing costs -developed a way of reducing has yet been made. Local call charging will will have to live with this legacy for many the thickness of concrete floor slabs without remain under the control of the ex1sting multi­ years to come. But at long last they can see impairing structural strength. phase pulse supply equipment at the larger some semblance of order in new internal By 'polishing' green concrete floors, a smooth exchanges. cabling distribution (lCD) schemes. level surface can now be achieved which avoids the need to lay floor screeds. Both time and Further References New layouts are planned, on the basis of materials are saved and the height of buildings Information may be found in Tl's E6 01703, E6 providing one pair of wires for every five square reduced, while retaining the same number of R5813 (Maintenance) A6 03029 (Installation) metres of floor space. A liberal provision on this floors. 'Vertical' building costs are therefore also and A6 C1095 (Planning). A self-teaching style scale means that BT has been able to adopt a reduced. Using this method of construction of course handbook has been produced by system using Insulation Displacement means that there is no longer space to bury floor BTTC Stone. Terminations (IDT), without the need for a cross­ trunking in the concrete without impairing its (01-432 2045) connection facility in riser shafts, for example. strength. It is also extremely difficult to plan With new lCD schemes, building cable-pair cable trunking in advance without knowing a records are a thing of the past because each pair tenant's requirements- a more common appearance in a box connection now simply problem with widespread speculative shows the building distribution frame (BDF) bar developments. There was, therefore, a clear and pair reference. Floor distribution points are need to adopt some means of telephone wiring no longer randomly scattered around an office, to overcome the problem of running cables to as each one is planned to offer pair distribution desk positions not close to skirting trunking­ throughout the building so that communication open plan office layouts for example. facilities have an equal probability of being easily Furthermore, the Health and Safety at Work Act connected to the lCD system. To achieve this, a requires that trailing cables and cords which simple and reliable practice was needed for present a potential safety hazard to employees connecting telephones to the lCD. are avoided. Equally, the same problem arises with traditionally screeded floor finishes where_,, the developer is not prepared to mstall floor To test the worst and best conditions, one floor constructed outlet boxes containing early trunking and conduits. was cabled under 'stuck-down' body carpet, the versions of the l1ne jack unit (LJU) wh1ch are other under removable squares. The cable is used to plug 1n telephone apparatus. IDT BTNE's solution held 1n position on the floor by self-adhesive techniques were adopted, speCial mass After being presented with particular cases of tape applied longitudinally over the cable. Two termination tools hav1ng been developed by the safety hazards by the Health and Safety types of flat cable feature in the scheme- cable manufacturers for this purpose. The 50- Inspectorate, BTNE decided to try a system of 50-wire specially protected against 'gnt' wire flat cable was also used as a 'bus' which flat, undercarpet cable developed by an penetration, together with 8- and 20-wire was intercepted at 'in-length tap-offs' to American consortium of cable and telephone unprotected. Figure 1 g1ves the cross sect1onal accommodate a liberal installation of parallel companies. A supply of cable was obtained and details of the cables used 1n the tnal. The flat connected key and lamp units. The creation of used to wire two floors of a new office building cables interface with traditional round cables in in-length tap-offs was a difficult operation and in Leeds for occupation by BTNE Service skirting trunking using multiway male and one which is unlikely to be adopted by BT as a Division. A standard lCD scheme using flat cable female connectors. At the desk positions, standard method. was installed to serve an open-plan desk layout. s1milar terminations are used in specially Two fitters from Leeds Area were given on­ Site tu1tion on the installation techn1ques. Their Figure 1. Cables used in the tnal enthusiasm for the system gave much 0.5mm copper conductors Polyester film (grit protection) encouragement to BTNEs design team. In­ house use of the new cable gave opportunities PVC sheath .. 11.25mm 14 Flame retardent cable jacket to ga1n first-hand experience without r1sk1ng ::::, I adverse customer reaction, and to monitor r- ' closely the performance of the cable. Faults on 0.9mm ~ ~ ( ~ \ the scheme were few, all but two resulting from L_ ' mechanical damage caused by carpet fitters. Two maJor no1se faults developed some time -2mm-l after installation. These were located to failure of the mechanical grit protection, causing -2.5mm- 52mm subsequent chemical corrosion of the cable l~------57mm------•l substrate. Laboratory analysis of the damaged cable identified penetration of the protective 50 wire 'protected' layer, allowing chem1cals within the concrete 0.5mm copper floor to react with the cable, producmg conductor insulation failures. The analysis demonstrated a 0.9mm 0.9mm need for further protection against grit penetration which is effected by placing an 100 (!) 00 \C!)C!)j additional layer of adhes1ve tape underneath the t cable. .,.______25mm ------• 1--smm I 20 w1re 'unprotected' 8 w1re 'unprotected' 12 The future 10m---- Inland HQ interest in BTNE's tnal- and cons1derat1on of the d1ff1cult1es and successes experienced- will lead to the adoption of under Cables to BDF carpet cable as an alternative to standard floor w1r1ng procedures. A cable spec1f1cation has been drawn up and a number of cable manufacturers invited to submit samples for LJU2A evaluation based on two sizes of cable, 6-w1re s>~ and 50-wire, w1th the aim of launching the 403 scheme shortly. Essentials of the flat cable specification are· • 0.4mm or 0.5mm conductor • suitable for term1nat1on on Connectors 226, preferably on s1te • must withstand point load1ng from off1ce furniture and personnel ~ LJU9A • resistant to grit penetration • imperv1ous to chemicals such as, concrete E sealers, carpet adhesives, carpet clean1ng 0 N ~~ fluids and solvents. Initially the use of measured lengths of 50-pair cable already pre-terminated on Connectors 226 1n a local workshop is one way of avoiding the need to purchase expens1ve mass termination tools for on-site use. Nevertheless, on-s1te termination is a future poss1b1l1ty once tool costs are reduced. Surplus cable wh1ch has to be 'lost' when us1ng measured lengths, is ach1eved Simply by folding the flat cable through a number of 90 degree turns. Six-wire cable offers the dual facility of e1ther c::::::J 50 wire flat cable underscrew term ~nation or I DC. 6 wire flat cable

Laying under carpet squares is strongly [::=:J Key & lamp un1t recommended. If the cable 1s la1d under body Box conn. 403 ,.... carpet, add1t1ons to the scheme and I --•--- replacement of faulty lengths will prove both L------~--_T_e_le_p_h_o_n_e_ difficult and time consuming Additional mechanical protect1on aga1nst gr1t Ftgure 2. Layout of the future - 13 ITEM DESCRIPTION TYPICAL USE in today's modern offices and, possibly, the Line Jack Unit No 7A Six l1ne jacks wired to home. It fulfils the requirements of the Health a Connector No. 226 and Safety at Work Act, offers scope for Interface flat cable imagmative use and reduces installation labour With plug ended costs resulting from easy lay and fast telephone cords L1ne Jack Un1t No. SA 12 l1ne jacks wired to termination methods. Couple these advantages a Connector No. 226 with the prospect of flat (low profile) coaxial cable, and the way ahead IS clear for a totally unobtrusive cable system. Because the 1nit1al cost of the cable will be h1gh- until large Boxes Connection Three, SIX or n1ne No. 403, 406, 409 Connectors No. 226 volume production is assured- consideration is parallel Wired being g1ven to charging a premium to those In length intercepts customers who specify its use either by design on flat cable and or because they will not accept a cheaper interface between standard alternative. From a maintenance round and flat cables Box Connection Two separate sets viewpoint there is every ind1cation that the new No. 426 of three Connectors cable will prove reliable- even in the harsh No. 226, each environment sandwiched between floor parallel wired coverings and structural concrete. We look forward to its successful mtroduct1on. (0532 467607) Lme Jack Unit No. 9A One Connector No. 226 Individual tap-off and single line jack from flat cable which can be wired at a telephone to any terminals of pOSitiOn the Connector

penetration will be offered by laying PVC of flat cable and connecting devices is shown in adhesive tape both under and over the cable. F1gure 2. Interface with telephone cords and lCD There can be no doubt that flat undercarpet schemes will be ach1eved using a number of cabiE1 will be a welcome addit1on to the range of items currently under development products needed to meet customer A typical layout usmg the proposed new range requirements- being aesthetically acceptable 14 Operations and tnaintenanee eentres

(OMC) -a key element in the introduction of System X

by Len Strickland LES 6.2.2 OMC called the operations and maintenance control (RSC). In this context. surveillance Current System X penetration unit (OMU). The OMU is usually located 1n an means that if a fault occurs on any of the System X exchanges- now called Telecomms exchange building- although not absolutely exchanges within the OMC catchment area, Exchanges D1g1tal (TXD)- are already in service necessary- and the accommodation is planned then the maintenance control officer (MCO) will in the UK. There are two medium locals (TXD 6) to be a pleasant working environment There are know about it He will know by two methods. at Woodbridge, Suffolk, and Arrington. near many activities performed at the OMU. as can An alarm message- relayed to an alarm­ Cambridge, and a trunk sw1tching unit (TXD 13) be seen from the organisation diagram- Fig. 1 receiving visual display terminal known as an in Cambridge 1tself. In London there is a tandem Figure 1 shows that the OMU has the role of alarm display and control unit (ADCU) The switching unit (TXD 12) at Baynard House. 'overall surveillance' and 'co-ordination of ADCU display will inform him of the identity of There soon will be a med1um local exchange at maintenance activities'. But it should be noted the exchange concerned and will give him a Hale. and a tandem unit at Lancaster House. that this excludes customer's line maintenance simple indication of the problem. For example. a both in Liverpool Area. since this is still performed at the repair service processor fault The ADCU gives the alarm - There are also two OMC's 1n service- at Figure 1. OMU organisation. Cambridge and in Baynard House. A th1rd OMC OMU will be brought into service in Liverpool to coincide w1th the open1ng of the Lancaster Role Overall surveillance. for catchment House TXD 12. In the next five years it is Co-ordination of maintenance activities area un1ts. planned to introduce about 60 TXD trunk un1ts. 300 TXD local units. and BOO remote concentrator units. An essential part of the TXD programme w1ll be to assess each Area's needs for OMCs. and to provide them accordingly.

What is the OMC's purpose? Functions OMCs have two ma1n purposes in the network • exchange maintenance • administration Co-ordinates Supports MC and Prov1des and Output data as explained here- exchange CMP functions; maintains circuits tape changing Prime maintenance deals with more (public and private) and agency activities Exchange maintenance activit1es on a difficult faults connected to System tasks Exchange maintenance. and other associated day-to-day basis requinng in-depth X units (does not include activities within a designated OMC catchment analysis customer's lines) area. are controlled from a staffed part of the 15 reports as numerical references in the range his location It serves also to put faults in priority example, to do agency tasks under terminal 1 to 15. At the TXD itself, there are 15 alarm order for attention. failure conditions at the remote end. The agency lamps which have a one-for-one The maintenance control funct1on (f1g 1) has tasks may be better understood by considering correspondence with these numbers, so the been described, but there are other functions in the administrative need for the OMC. ADCU at the OMU gives a replica for every the OMU. exchange within the area, using a single display. Circuit maintenance and provision (CMP) is Administration There will also be a detailed fault report which perhaps fairly straight-forward, but the others With TXD, the operational and subscriber's is assembled by the maintenance control sub­ may require a little more explanation. Technical facil1t1es and the network configurations are system (MCS) of the TXD concerned and support (TS) -this is an activity wh1ch becomes determined by software and data loaded onto directed, or streamed, by the OMC processor to necessary with exchanges based on the the TXD. To interrogate the data, or to change 1t the MCO. The MCS report will be received on a technology used with TXD. Elusive faults- for (temporary out of service a Ime, for example) visual display terminal (VDT) on the MCO's work example, intermittent or incipient problems­ requires only to input commands from a position in the OMU. This will have added will occasionally occur. terminal havmg access to the exchange and information on the previous fault history. This The technical support engineer would be able w1th the user having the necessary access MCS fault report will also be automatically to review fault histories using a 'browse' facility, rights. Many termmal users come mto this stored on disk on a current fault file and the and do the correlation work necessary to track category, some engmeenng and some non­ MCO can access this file from his VDT to add down the problem. He would do th1s without engineering. comments. For instance, he may record that the d1stract1on of having to respond to new The OMC acts like an exchange for all this fault has been ass1gned to a particular alarms, leav1ng these to the MCO. terminals provided remotely from the TXD (this engineer to deal with. even mcludes exchange maintenance terminals This brings in the co-ordinat1on of the Man-machine language at remote concentrator units (RCU). maintenance activities aspect, since 1f the TXD Whenever an exchange engineer wants either Remote terminal users outside of the OMU concerned is an unstaffed unit, then the MCO to input commands from his terminal to the are classified as non-OMU, and seven of these will need to contact an engineer to go to the OMC processor, or to a TXD, he has to use have so far been identified. These represent the exchange. When the engineer goes to site he System X man-machine language (MMU. To administration services provided by a Telecom will be able to perform the necessary obtain commands necessary for a particular area office- procedures from a local control point (LCP) task, he needs to consult documentation known • sales office terminal and to clear the fault- poss1bly by as the operations and maintenance manual • customer services changing a faulty slide-in unit. He will also be (O&MM). Initially, the MML will seem strange • Auto-manual centre (AMC) able to directly interrogate files at the OMC from and often complex; but as experience is gained, • territorial accounts group (TAG) the LCP since there will be a work list called the eng1neers become very profic1ent 1n th1s field, • repair service control (RSC) technicians work program allocated to him. This and may need to refer to the O&MM only for the • trunking and grading duty is useful, since he may well be responsible for a little-used commands. Operations support (OS) • installation control office number of TXD exchanges- one of which could at the OMU is necessary to aid other OMC An example of a task performed at the have become faulty while he was travelling to terminal users outside of the OMU itself; for terminal would be a 'one-off meter reading. A 16 TXD Both way data link ~nteractive OMC terminal ~ OMU interactive terminal rack mounted hardware for this OMC is TEP 1H Hardware Eg practice- the TXD standard. A switching Local control ~ Alarm VDT ie Alarm Display Alarm link Processor processor is also used -the pre-processor po1nt and Control Unit (ADCU) utility (PPU). Two more of this type of OMC are ...... scheduled, at Coventry and Leeds . . .·cs . However, it has been recognised that a : •••••••••••••••••••••• ~ ADCU . switching processor is not ideally suited to the . Out-of-hours . tasks required of an OMC. Also, advances in : alarm system : -DRemote technology have out-dated the original design, Figure 2. Simplified administration network diagram. Terminal ...... eg at RSC so a successor to OMC1 is in the pipeline, known as OMC2. It will have some major differences, and will not be available for two or TAG officer with a terminal could do th1s, but if • a bothway data link to enable fault and other three years. In the meantime, a small-scale the engineer at the OMU (OS function) does it. it data to be passed to the OMC, and to provide development known as the 'Basic OMC' is would be an 'agency' task on behalf of TAG. a path for requests from OMC terminal users expected to bridge the gap. Basic OMC uses The introduction of System X remote to interrogate data stored at the TXD, or to micro-computer techniques, such as local area administration facilities, using VDTs, to users change it network (LAN) or multi-user multi-processor such as sales office and TAG has identified the • a separate link for alarm messages from the (MUMP) methods. need to develop a man-machine language which TXD overlay to the alarm recept1on equipment One thing is certain. That is, that OMCs will is more suited to the1r needs that the at the OMC. In the event of OMC processor be recognised as a valuable part of the System X engineering-oriented language currently failure this equipment would still be operative. programme, and experience gained on the provided on System X. As each TXD is brought into service in the present generation will be essential input to Thus an MML 'translator' has been developed area, it will be connected to the OMC. future OMCs. which provides such user-friendly facilities as Figure 2 also shows an ADCU at a repair (01-432 1344) 'menu mode' work1ng, and simplified service control (RSC). The RSC could be a transactions. These will be incorporated into all .. nominated out-of-hours surveillance point for future OMCs. exchange alarms if the OMU itself was not a 24- hou r staffed centre. How OMCs fit into the network Figure 2 shows a simplified adm1n1stration Future OMC developments network diagram. This is the network which is The OMCs which are in service at Baynard used exclusively for BT needs, and cames no House and Cambridge, as well as that to be public switched telephone traffic. shortly introduced into service at Lancaster When a TXD exchange is to be connected to House, Liverpool, are a form of OMC known as an OMC, circuits must be provided as follows- OMC1. The processor and most of the othe~ 17 TXE4: Present perfornaanee and future targets

by Peter Jones LES4.2.2 DMAC: D MSFs: TXE4 is now one of the major exchange The results for MAC Sequence 1 (own The MSF performance of TXE4(RD) is very poor. systems in British Telecom. At present there exchange calls) show that TXE4(RD) performs The current mean-time-between-failures are 245 TXE4{RD)s in service with another very well; at the time of writing it has the best (MTBF) IS only 14 months. A lot of work has 105 to be brought into service by 1985. MAC figure of all systems. The good MAC been carried out in this field and some twenty­ TXE4{RD) has been joined by an improved figures highlight the anomaly of high customer seven design deficiencies (DDs) have been design know as TXE4A. of which five are reported faults as opposed to good measured identified. However. it is encouraging to know now in service with another 229 to follow by performance. that no new DDs have been discovered since 1989 {fig 1 ). At the moment service is Fig2 provided for about 2 million customers but Fig 1 eventually TXE4 will have a capacity of OUR SLICE OF THE CAKE (max exch. connections) nearly 8 million connections {fig 2). Total584 1989 (Maintenance News 10 described TX£4, and No. of 1983 MN16 described TXE4A). Exchs

PRESENT PERFORMANCE TXE4(RO) The present national performance of TXE4(RD) can be judged from three main information sources- 1983 1989 1.3% • A51 Results (Line 28: Customer reported Exchange Faults faults) see fig 3 per EC per Total exch. 1.0% • MAC test sequence 1 (own exchange calls)­ Annum Faults fig 4 (MACs are Measurement and Analysis 0.7 Centres- see MN11) Customer Reported Faults • Major Service Failures (MSFs) see fig 5. • TXE4(RDI Target 0.5% DA51: The customer reported faults are higher than we might expect for an electronic common control o 1 system. especially with a second attempt 0.03 facility. This is an area currently under ALL TXS TXK TXE2 TXE4(RD) investigation by BTHO. Fig 3 Fig4 ALL TXS TXK TXE2 TXE4 18 Future Targets • MSF- The majority of MSFs are caused by In the future it will not be possible to show the working parties. mostly as a result of careless nat1onal performance of TXE4(RD) and TXE4A act1on. Extra care must be taken when separately due to the method of data collection. working on or near sensitive areas of the The future national targets for TXE4(RD.4A) exchange and the rear of racks, if this are- disappointing aspect of TXE4 is to be Fig 5 TXS TXE2 TXK TXE4(RDI • Customer reported faults: 0.03 per exchange improved. connection (EC) per Annum by mid 1984 Much work has been carried out at BTHO, August 1981, so it looks as though we have • MAC own exchange call failure due to plant Regions and Areas to improve performance, and identified all the causes of MSFs due to DDs. defects: 0.2% by mid 1983 this has paid dividends. But we have now Works specifications have been issued. or are 1n • MTBF: At least 5 years by mid 1984. reached the point where further improvements an advanced state of development. that There are many things in the p1pelme which to TXE4 depend substantially on the effective overcome all but one of the DDs still under should assist in achieving these targets, use of all the available maintenance aids. With invest1gat1on The implementation of these including. carefully applied maintenance techniques. TXE4 works specifications 1s already startmg to • Use of Network Analyser PATE4 (see MN21) can out-perform all the other existing systems. improve the MTBF, but even when they have all and other maintenance aids (01-432 2457) been implemented TXE4(RD) will still have a • Improvements to routiners (outgoing JUnction very poor performance when compared with (OGJ) and Link) other systems. The reason for th1s is the • Works specifications to improve des1gn number of MSFs caused by Working Part1es. At weaknesses present they account for over half of all MSFs, which is equal to all the MSFs in TXE2 and TXK 1 However. there is act1on we can all take 1n put together Most of these failures were order to meet our targets- caused by carelessness, and responsibility l1es • A51 - If a customer reports a fault that is equally w1th BT mamtenance, BT construction subsequently proved to be in the exchange, and contractor's staff. answer the question- "Why didn't we find the fault first?" TXE4A • MAC- Ensure that routiners are used TXE4As are perform1ng well and all the effect1vely by following up all the faults shown indications are that they will prov1de a very good in the printout, Including a check on busied service 1ndeed. However, the1r contribution to circuits. It 1s well worthwhile having a tick the national targets will not be significant until sheet to highlight those circuits that regularly about 1985. appear in the printout 19 The Anallassador Eleetronie Switehing S~stena (ESS} by John Bright RA 152 unit and line terminations for neatness and ease with microprocessor control circuitry The Ambassador electronic switchmg system of installation. The cabling to extensions was The CCU microprocessor IS the brain of the (ESS) is a microprocessor controlled operator­ kept straightforward and consisted of a speech system and constantly scans the extension data less switching system designed to cater for the pair and data pair direct from the CCU to each and exchange line interface circuits. Whenever smaller house exchange system (HES) and extension. This enabled extensions to be added, there is a change in condition, it refers to its extension plan markets. recovered or shifted with the minimum program and responds accordingly. Ambassador ESS was trial led in Newcastle­ alteration to ex1sting wiring. For example, when an incommg ringing signal upon-Tyne and Southampton telephone areas Three sizes of EPS were developed, these is detected by the exchange line interface during the Summer of 1982, and will soon be were the 1 +3 and 2+4 systems and the 5+ 10 circuit, the microprocessor detects the change available nationally. growth system. in condition and is instructed by the program to The EPS 1 +3 and EPS 2+4 systems became signal the extension telephones. Data signals Development the Ambassador ESS (1 +3 and 2+4) The EPS are sent to the extension telephone The Ambassador ESS was known during its 5+ 10 has since become known as the Senator microprocessors which decode them to l1ght development as the electronic plan set (EPS) call connect system and is now also undergoing the calling LED indicators and sound the and formed part of the range of modern national launch. This uses the same extens1on buzzers. equipment developed during recent years to telephones and adaptor units as Ambassador When an extension answers an incoming call, supersede the 700-type instruments. ESS but has slightly different operating the telephone microprocessor signals the CCU This range includes the basic Ambassador procedures and is aimed at the key and lamp microprocessor wh1ch then sets up the telephone, Accord loud speaking telephone, and larger HES markets. switching matrix between exchange and Herald call connect system and various add-on Senator was designed for modular growth. extension speech pairs to complete the call units all of which have the same profile to give a The central unit contains slide-in circuit boards path. All signall1ng between the CCU and matching appearance and distinctive house and comes equipped for up to five exchange extension telephones (except under mains fail style. lines and six extensions. Extension capacity conditions) is carried out over .the data pairs. Reliability and ease of installation were prime may be increased to a maximum of ten by the objectives in the design of the EPS and resulted addition of extension interface circuit boards. Extension Telephones in the adoption of a central unit 'star' Ambassador ESS extension telephones are configuration connected to extension ESS Central Control Unit (CCU) similar in appearance to the basic Ambassador telephones by means of four-wire cablmg. Thus There are two sizes of CCU, the 1 +3 CCU being telephone, they are slightly wider and have an the traditional multi-wire concept- which is 300mm long by 190mm wide by 75mm deep, additional column of buttons and LED indicators time consuming and costly both in installation and the 2+4 CCU slightly larger at 480mm long. to the nght hand side of the keypad The and maintenance- was avoided. The CCU comprises a power unit, line and additional column of buttons and LED indicators The central control unit (CCU) was designed extension terminations and a single circuit board form part of the plan module which to be wall-mounted and contain its own power containing a relay speech path switching matrix communicates with the CCU over extension 20 cabling data pairs. The top two buttons of the replaced by a magneto bell and bell adaptor if customer using the extension telephone plan­ plan module are for accessing exchange line(s). requ1red. module buttons. the middle three for direct named press-button A series o.f adaptors have been developed to Intercom and the bottom two for divert, hold Facilities further expand the facilties of ESS and these will and exchange line ring programming facilities. Although the Ambassador ESS is a small soon be generally available. They include: The keypad functions as a normal keypad and switching system it offers many of the facilities • Extension Bell Adaptor, to provide magneto is available in two signalling versions; the self­ of larger systems, including:- bells at an ESS extension instead of the contained loop-disconnect pulsing vers1on is for • press button access to exchange lines for internal electronic buzzer. Ambassador ESS systems working to Strowger outgoing and incoming service. • External Extension Adaptor, to permit a pulsing exchanges or PABXs, and the MF4 • direct named-press button intercom to other standard 2-wire loop-disconnect pulsing signalling version for working to exchange or ESS extensions. telephone to replace an ESS telephone at an PABXs with multi-frequency (MF) signalling • Exchange line hold for secret enquiry calls. extension. capability. • Diversion of intercom calls to another ESS • lnter-PBX Extension Adaptor, to replace an Ten address, X-Press Callmaker versions will extension. ESS extension and provide inter PBX tie-line soon be available as an added attraction. • Programmable ringing on exchange line calls facilities and remote answering facilities. Ambassador ESS extension telephones have (bell off facility). The provision of adaptors is documented in electronic 'buzzers' instead of bells to provide The facilities are all easy to use and the Ambassador ESS handbook. audible signalling. These are quite adequate for programming for exchange line ringing and the normal office environment but may be intercom call diversion is carried out by the Maintenance The design of the central unit is such that only fuses can be changed on site. Maintenance of Central the system is therefore restricted to checking control cable and wire terminations, changing fuses and unit replacing standard items within the terminal 4-wire cabling to extensions instruments. Beyond this the requirement is for complete unit/terminal changeout. The Ambassador ESS handbook (Customer Apparatus Guide Notes 0012) contains a detailed system description and the maintenance section includes a logic faulting chart to assist in identifying faulty units. As with many newly developed items of customers apparatus, service problems have been encountered and these are being corrected. Full details of those problems identified to date and their solutions are published in the Ambassador ESS and Senator CCS Newsflash series issued by BTHO/RA 152. (0 1-423 2349) 21 New housings for Pulllie Call Offiees (PCO)

by Dave Popham ID/CE4.2.2 mamtained in good condit1on by our own staff ex1sts or- if wall support IS ava1lable- the and Maurice Bradley BTL/S4.1 .3 without requ1ring special 1st treatment. Anti­ module can be bolted to a floor and t1ed back to To meet growing pressure from developers graffiti paint is an opt1on. the wall. The k1osk may be bolted to a and local authorities, BTL, supported by The mam members of the Croydon fam1ly all concreted-In base frame or to a paved surface. BTHQ, have developed a range of PCO use the same back module. Th1s IS log1cal since Precast. domed, non-sl1p slabs can be prov1ded housings to replace our previous sole all perform the same functions- mount1ng the to g1ve good drainage and th1s avo1ds the central offering- the Kiosk No 8. They are called the same equipment, and lead1ng~1n and term1nat1ng wear, wh1ch 9reates a puddle for users to stand 'Croydon' range to acknowledge the electrical, telephone and earth cablmg and in on wet days. Alternatively, surroundmg contribution of BTL South Area staff who wiring. pav1ng can be continued stra1ght through. translated the sketches and ideas into The module consists of two 120x60mm hardware (and added some of their own). HRMS posts, connected by a 3mm steel sheet Cheery glow The range compnses a kiosk. an 1nternal back panel. Welded to the back panel are Booths may be 'su1ted' by shanng adJacent booth for concourses and l1ke Situations, and an horizontal sect1ons of 'Un1strut' to wh1ch the support posts and s1de screens. but th1s IS not external booth for qu1et environments. There IS equ1pment fix1ngs can be bolted. Intermediate so with k1osks because of the large stock of also a wall~mounted vers1on of the Internal fixings are obtained usmg short lengths of alternative components needed. Kiosks and booth. These housings all have a fam1ly Unistrut as movable ladder bars between the booths can be mstalled back to back. The k1osk resemblance and are JOintly recognisable as pnmary sect1ons. In th1s way f1xmgs may be may have s1de or front door opening w1th left or 'Brit1sh Telecom' rather than 'Post Off1ce' made at any point for any type of equ1pment and nght hing1ng. property. There 1s no anti~vandal model1n the they can be easily repositioned at any time 1n All housmgs have steel ceilings w1th a central range, since the requirements for such a the future. opal acryl1c light1ng panel. Th1s h1nges down to housmg are not compatible with a 'c1vil1sed' A plast1c~faced wall board h1des the Un1strut allow standard (No 12) fluorescent l1ghtmg un1t design. So 1t was decided that the 'Oakham' 1n the upper part of the module and can be used tubes to be changed Without using steps. The booth would continue to fulfil that need. itself for the screwed f1x1ngs of l1ghter lt.ems installation IS double Insulated. The Croydon range was designed by The lower sect1on of the module has a Above the ceil1ng IS an acryl1c and alumin1um engineers w1th long expenence of PCO services termination chamber w1th removable dome, wh1ch has e1ther opaque black characters installation and maintenance. Although covers to house electrical sw1tchgear and earth for a payphone or translucent green characters essentially practical, general reaction to the term1nat1ons. The whole base area of the for a cardphone. The dome IS Internally lit from appearance has been very favourable. chamber 1s available for UG cable lead~in. All the s1des of the lightmg fittings and at n1ght The bas1c structural materials are hollow cabling is completely concealed. Alternative gives a warm cheery yellow glow to advertise rectangular metal sect1ons (H RMS) and sheet high-level cable entry can be prov1ded. the presence of a payphone. steel- chosen because they are easy to obtam, The corner post bases conta1n welded-in The dome also houses the (standard) door cheap, rugged and can be fabncated 1n large or threaded plates wh1ch connect to a base frame closer, its spmdle projecting down through the small quantities 1n vanous workshops- m the concrete foundation, making it very strong ceil1ng. New geometry for the closer arms 1ncludmg our own- throughout the country. A and r1gid for a free~standing booth. Alternatively, makes for eas1er openmg and prevents doors pamt fin1sh was chosen because 1t can be 'feet' may be used where only shallow depth from being torn off their hinges in high wmds. 22 Restraining straps across the standard (No 2) wallboard. The wallboard IS the same Width as less vandalism than kiosks. hinges are not necessary. that in the KB and K6. So, not only are the The colour scheme adopted for the range is: In the kiosk, six identical panes of glass are equ1pment layouts consistent in all the outside back panel, rear corner posts and dome set 1n rubber channel and held by angle 1ron hous1ngs, but new-style notice frames being in yellow; all other framing and wallboard 1n glazing beads pop-rivetted into place. The r1vets developed for use in existing kiosks can be used black. are drilled out when necessary. The glass in all 1n Croydon housings. The slim framing and large areas of glass g1ve housings is bronze tinted, 6mm armoured. In a light and airy appearance and the h1gh level of the booths, glass is set in rubber and stainless Windswept illumination (32 watts) ensures good visibility of steel channel, which is removed for re-glazing. Another feature of the kiosk is the 1OOmm occupants to discourage fouling or other space left below each fixed side and the door, abuses. Standard wallboard layout so that rubbish can blow out in the wind. This Initially about 50 kiosks have been ordered by In the present Croydon design a single, full­ reduces the level of acoustic protection for the BTL for trial, and 25 for BTHO. Seven internal width, polycarbonate not1ce cover is provided at user, but the gain in cleanliness and ventilation booths have been installed at Bnstol Temple the top of the wallboard, retained by heavy steel is considered to outweigh the increase in noise Meads station, as a trial for British Rail. If bars top and bottom. The sides are unframed level. As there will be less difference between accepted by BR the booth will become standard but protected from prising or levering by being the protection offered by a kiosk and that by a for use on BR mstallations throughout the set back some 75mm between the steel corner booth, we may well be able to use a high country. Milton Keynes Development posts, which also protect the sides of the proportion of the cheaper booths. Booths attract Corporation is currently considering the wall­ mounted booth for the first indoor PCOs in the A suite of Croydon internal booths at Temple Meads BR station The Croydon kiosk illuminated covered shopping area. They have also shown interest in replac1ng all Milton Keynes kiosks with Croydon housings, but this has been resisted on grounds of cost and availability. The f1rst kiosks have been erected in Leicester Square and Oxford Street, 1n London and 1t IS BTL's intent1on to use them on other prominent sites, gradually extending their use as opportunity offers. (01-432 2772) Dave Popham (01-735 3713) Maurice Bradley

23 Lightning proteetion of naodern equipnaent by John Haggart T8.2.1 investigated, the cost of fitting protection as aerial cable or dropwiring, and wh1ch pass In 1980, lightning activity resulted in the given in the Instruction, would have been much through and terminate wholly in built-up areas. isolation of two TXE4 exchanges and less than the cost of repa1r work during a s1ngle Such areas typically include city centres. heavily highlighted the need to review lightning season. built-up commercial and industrial distncts and protection policy. The Tl A2 E0601, relating to the protection of urban high-density residential areas. Protect1on Lightning can cause high voltage surges in the digital, electronic and crossbar exchanges- and is needed on ail other lines- including those network as a result of d1rect strikes to cables, or also PABXs- recognises the Importance of which pass through rural or low-density from induced surges due to strikes adjacent to protecting both public exchanges and residential districts, even though they may overhead and underground telecommunications customers' terminal equipment. In the case of terminate in a built-up area. plant The frequency of occurrence and the privately-owned-and-maintained PABXs 1t IS for In addition, lines with more than one severity of these conditions varies according to the customer, acting on the advice of his overhead span, including dropwiring, need the nature of the terrain, the screening effect of supplier, to decide on the protection required. protect1on at the MDF even though 'pole top' buildings, and the type of plant construction. But clearly there 1s no objection to the customer protection as given in Tl A2E 0504. Modern electronic equipment is more being advised of BT protection policy. susceptible to damage by lightning than the How should protection be fitted? robust electro-mechanical equipment previously Exchange protection Termination blocks capable of taking lightning used for switching purposes In considering the vulnerability of a line to protectors should be provided on all cables at Information on the incidence of damage to lightning surges, the main factor to be taken into new exchanges. But the extent to which both protected and unprotected exchanges account is the level of screening afforded by protectors actually need to be fitted will depend leads to the conclusion that, when f1tted, other buildings and services. In city centres, upon the environmental factors already protection equipment is effective in preventing buildings and plant in the ground such as metal mentioned. Where more than 75% of the lines damage. Conversely, there is a significant risk of pipes and armoured cables, together w1th in an exchange need protection, every line in the serious damage to equipment 1n vulnerable additional screening that may be provided by exchange should be protected. Where areas if it is unprotected. Current instructions on high conductivity soil conditions, will reduce conditions are such that less than 75% of the the provision of lightning protection are not surges to a low level. Where such protective lines in an exchange require protection, the mandatory and they cannot contain adv1ce screening doesn't exist, then surges severe exchange area should be sub-divided into applicable to every circumstance. The enough to damage equipment can occur- even smaller areas- typically an area served by a instructions do, however, define a standard of on wholly underground cables. primary cross-connection point- to determine protection which constitutes an economic mean which lines require protection. Protector between the cost of fitting protection and the When should protection be fitted? mountings should preferably be provided on the cost of repairing damage, including out-of­ The only lines on which MDF protection is not line-side of the MDF, as this facilitates service time and maintenance, if protection has necessary are those which are wholly identification of lines needing protection. But been omitted. In a number of cases underground, or have no more than one span of whether or not this can be achieved at new 24 exchanges will depend on whether or not the principles- previously outlined- for the see Tis C3F 0051 and C3F 0052. MDF is tore-terminated. protection of exchange equipment (TI A2E The three-terminal GDTs used are self­ In the case of exchanges which are at present 0601). The following summary as to where restoring devices, the end terminals being unprotected, the cost of providing prqtection protection should be fitted may prove a useful connected across the line and the centre and the degree of disturbance their provision is aid in this respect. Protection should be terminal to earth. To ensure efficient operation likely to entail will depend on the type of MDF provided where one or more of the following of these devices it is essential that they are termination in use. A range of hardware is apply: connected to an earth of less than twenty ohms available for retrospective fitting of protector • the customer, or the serving exchange, is resistance. Achieving this low value of earth mountings, see A2E 0601 for details. sited in an area which is not built-up resistance is not usually a problem at exchanges • the external cable line passes through an area but it may prove more difficult at customers' Protection of customers' terminal which is not continuously built-up premises. equipment- call connect systems and • there is more than one overhead span in the PABX's customer's line You can help Customers' modern call connect systems­ • the serving exchange has protectors provided In the competitive environment in which BT is particularly electronic equipment using stored on the cable concerned now operating, it is essential we maintain our program control- have proved vulnerable to • there is any record of past lightning damage. position as a supplier of reliable terminal voltage surges from lightning and other causes. Protection should normally be fitted at the apparatus. Experience has shown that Equipments in this category include Monarch, first cable termination point in the customer's maintenance costs- and service interruptions­ Herald, Ensign, Regent. Viceroy, Senator and premises. If this is not convenient- as may can be significantly reduced by proper others. typically occur in a multi-tenanted building- it application of lightning protection practices. To Reports of damage to such installations have may be provided at other terminating points in assist IDHO in assessing the effectiveness of shown that the recommended protection had the building. current protection policy, we would welcome not in all cases been provided. The susceptibility information from the field concerning of this type of equipment to damage by How can protection be fitted? equipment failures attributable to lightning. relatively small voltage surges is causing At large installations protection can be provided (01-739 3464 Ext 433) concern and is the subject of detailed on the building distribution frame (BDF) by investigation within IDHO. Meanwhile it is means of Strips Connection which are of the important that existing lightning protection insulation displacement type and into which recommendations are adhered to. Protector Mountings, incorporating 3-pin gas discharge tubes (GDTs). can be plugged. At When should protection be fitted? smaller installations the Box Connection 300 The protection of customer's electronic call series, in which the above items can be connect systems should follow the same mounted, should be used. For further details 25 KILOSTREAM-Fault handling proeedures

by John McKenna SSE1.3.2 have been made for the London X-Stream passed to the Manchester XSC when In this article, readers are introduced to one Service Centre (XSC) to be staffed to accept appropriate of our new services, and informed about customer fault reports 24 hours a day. 7 days a On receipt of a fault report the a 1m is for the what is being done to ensure that our week, all year round. Outside normal work1ng XSC to remotely access the circUit in quest1on at customers remain satisfied with BTs hours. customer fault reports directed to the the appropriate CCS and - under remote maintenance operations. Manchester XSC willl be automatically re-routed control- carry out all necessary diagnostiC The national private circuit digital network to the London XSC tests. Faults are then handed out to the (NPCDN) is a pre-provided network based on appropnate point for clearance. digital junction and main network plant. As its Handling procedures Since all items required to totally implement name implies. NPCDN is dedicated to the Outlined below are the fault handling this strategy will not be available at the opening provision of private circuits. procedures at XSCs, NPCDN cross-connect date of the network. the strategy will be phased­ When these derived private circuits present a sites (CCS), serving exchanges (SE), and by field In over about three years. as Illustrated by digital interface to the customer- by means of maintenance staff dealing w1th fault reports on figures 1 and 2. The prinCipal factors of each a customer-located data circuit termmat1ng Kilostream and speechband private circu1ts phase are - equ1pment- the signals on the circuit are truly derived from the NPCDN DPhase 1 digital in nature throughout the network. The fault handlmg arrangements are based on • Circuit records entered on the Computer customer to customer. These d1gital circuits are two XSCs, London's Baynard House and Ass1sted Mamtenance for Spec1al Serv1ces known as the Kilostream service and allow the Manchester's lrwell House. The function of an (CAMSS) at XSCs. (Fault handling and synchronous transmission of digital data at XSC IS to act as the mamtenance control and either 2.4, 4 8, 9.6, 48, or 64kbit/s. NPCDN can customer fault reporting point for those NPCDN­ Manchester's XSC also be used to provide normal 2-wire or 4-wlre derived private mcuits which are 'A-ended' presented analogue private circuits. Kilostream within that XSCs temtorial area of responsibility. is one of the range of X-Stream dig1tal services These are- which also includes Megastream, Satstream, • London XSC- BTL. BTSE, BTSW, BTEast and and Packet Switchstream. BTWM The facilities offered by the X-Stream range of • Manchester XSC- BTM, BTNW, BTNE and services are intended to enable BT to compete BTScotland. successfully with the facilities offered by rival Customers wishing to report a fault may telecommunications carriers- such as contact the appropriate XSC either by Mercury. • dialling the nat1onal number for the London or In this new communications environment, it Manchester XSC (01- or 061-236 3371) is essent1al that the qual1ty of customer service • asking the telephone operator for 'Freefone provided by BT is at least equal to that of the 3371' competition, both during and outs1de normal • dialling telex 893927. All fault reports by telex working hours. Recognising this. arrangements are received at the London XSC, and will be 26 Fault reports Figure 7 Phase 1 and 2 fault handling procedures for Fault reports from customers ~ private circuits denved from NPCDN. from customers Faults handed out ~ ~ ~ 'A' end CCS co-ops Customer Repeat faults Repeat faults XSC carries Customer with other CCS apparatus fault or difficult or difficult out primary apparatus fault and/or obvious from problems problems diagnostic obvious from fault serving exchange fault report. tests report or. end to PCM staff to or end-to-end t end testing by Technical locate fault testmg by FMOs required support FMOs requ1red 1 (DATE C) Technical t support Fault located to (DATE C) I ~ + + ~ 'A' end CCS H1gher Other CCS Serving Local end/ ' order exchange customers XSC hands out digital premises faults to ! system j 'A' end CCS 1 ~ clears Fault passed Fault passed 'A' end CSS fault and Fault by 'A' end CCS by 'A' end CCS informs XSC informs XSC passed by to CCS for to serving of fault of clear. appropnate* attention. exchange PCM location CCS to 'A' end CCS staff for CCSforCCS XLP for XLP for its local informs XSC attent1on. equipment serving exchange local end RS for of fault 'A' end CCS faults equipment or customer attention location informs XSC XSC passes faults located faults of fault fault to the XLP ~ ! location for RS 1nforms CCS clears attention. appropnate fault and ! CCS of informs XSC Serving ~ serv1ce of clear. exchange XLP mforms restoration. clears fault XSC of fault XSC adv1sed ofl fault clearance CCS informs and 1nforms clear ~ xsc xsc XSC advises customer of serv1ce restoration

Figure 2 phase 3, 4 and 5 fault handling procedures XSC advises customer of clear. for private circuits derived from the NPCDN 27 availability of d1agnost1c a1ds, the pnmary I Maintenance officer I Customer objectives are the same. Once e1ther the or agent Progress general area of fault, or the faulty item has been Progress diagnosed, fault clearance will be effected most Distant Maintenance reports TEO rap1dly and efficiently 1f the fault is passed for sub-control control and 1:lttent1on to staff w1th the appropnate expert1se Normal (CCS, SE) IXSCI Technical DATEC to deal with the problem. It is essential, co-op problems therefore, that an XSC hands out faults for Organisational attention to the correct point in an Area. S~nce problems Distant Local the duty dealing with any one particular kind of expertise may vary from Area to Area, it IS not area area Local f Distant I xsc I I easy tor an XSC to decide who best to pass area SSM manager J SSM L I J specific types of faults to within an Area. For this reason, each Area has nom1nated po1nts ~ Excess duration called X-.Stream Lla1son Po1nts (XLP) ~to lia1se reports ~ w1th the XSC on NPCDN matters. Customer complaint Note: SSM=Special services manager The XLP will also arrange for staff to go to repeat fault EE. HD, etc of unattended serving exchanges, and so on, and long duration fault appropnate to arrange f1eld maintenance officer (FMO) difficult problem area attendance at customers' premises as and Figure 3 Escalation and technical support when requ1red. • Remote Access Test Equipment System statistics facilities not yet available on I RATES~ see MN20) gradually introduced at Service to the customer CAMSS) SEs will give remote test access to analogue­ It is essential all staff real1se that, in the near • No c1rcu1t test access from XSCs presented Circuits future, customers dissatisfied with the serv1ce • Primary diagnostic testing by CCS • XSCs have access to CirCuit/system alarm provided by BT will be able to sh1ft their custom (co-operation required at customer's premises information. to another telecommunications earner. In to apply circuit loop-back on analogue DPhase4 maintenance, one way to m1nim1se customer presented circuits) • XSCs have the statistics facil1ty added to dissatisfaction w1th service 1s to keep out-of­ DPhase2 CAMSS service times to a m1n1mum when faults occur. • XSCs have fault handling facil1ty added to DPhase5 Once a service-affecting fault is reported~ or CAMSS • AutomatiC Cross-connect Equipment (ACE) ind1cated by an alarm, for example~ the pnme • customer-located analogue and d1gital loop­ introduced at cess, allowing remote test objective must be to restore customer service. back dev1ces both capable of being remotely access to wcuits at CCS. Whenever faulty plant can be by-passed, this activated from CCS and also SE should be done~ the actual fault being cleared DPhase3 Area X-Stream Liaison Points (XLP) subsequent to service bemg restored. • XSCs have test access to all circu1ts by The detailed operating procedure for each of Future articles will go into more detail on the manually patching circuits to a Remote these phases 1s too lengthy for this magazine NPCDN and related top1cs. Access Test Port (RATP) at CCS Although the methods differ due to the (01-432 9162) 28 Conaputer naaintenanee in British Teleeona

by Kevin Jeffrey LES4.14 the national computer-based projects. Current Experience This article describes the development of BT already mamtains and repairs v1sual display BT has already set up Area Repair Centres computer maintenance within British units (VDUs) used with the Telecommun1cat1ons (ARCs- see MN17)- some equipped with Telecom. It outlines our policy, and how we On Line Data (TOLD) system (MN9) TOLD sophisticated automatic test equipment- in the are beginning to implement it by using the gives Area office staff communications and majority of telephone areas and more are existing experience and expertise we can call computer facilities tor entering data directly for proposed. These centres are geared to the upon within the Business. subsequent process mg. It replaces manual form repair of electronic equipment, Initially on call tilling, the use of intermediate data conversion connect systems and System X equipment. But Policy centres, and provides users w1th on-line the facilities which are available, and the sk1lls Up to now it has been the usual pract1ce for interactive checking of their 1nput records. The developed by repair centre staff also form an computer equipment suppliers to maintain the TOLD system already uses several thousand ideal base on which to build the repair of systems in use by BT. As the number of VDUs. computer equipment systems is likely to grow considerably, the There are two other large computer projects Likewise, BT staff have been doing first-line question of whether BT should itself assume in the process of implementation, which have maintenance of Cossor VDUs used on the TOLD responsibility for the maintenance of 1ts own significant potential econom1c benefits to BT in project, as well as maintenance of modern telex computers has been under consideration. terms of computer maintenance. One is terminals- Puma and Cheetah which require Taking into account serv1ceabil1ty, financ1al ARSCC: Administration of Repa1r Service similar maintenance techniques to printers used factors and staff skills 1t has been decided that­ Controls by Computer (see MN21) The other is with computers. Dthe maintenance of small business computers Mechanisation of Order Handling (MOH)- the BT Factories Division provide, a central repa1r (SBC) and mini-computers used 1n-house computensed Advice Note procedure. facility for disc dnves and processors assoc1ated should be undertaken by BT The significant feature of the three projects with GEC 2050 computers used in Dthe maintenance of selected computer mentioned, is that their implementation Injects Measurement and Analysis Centres. terminal equ1pment and in-house should be large volumes of computer equ1pment into The experience gained 1n organ1s1ng, undertaken by BT Telecom Area off1ces, telephone exchanges, supporting and operating the variety of DBT should not maintain and repair mainframe telecom eng1neermg centres (TECs) and other maintenance arrangements for these systems computers and their peripherals at the present locations. TOLD, MOHand ARSCC will account puts BT in an ideal position to expand its time. L1kewise the maintenance of software for over 10,000 VDUs with1n BT- on average computer maintenance act1v1ties. should be excluded from the responsibility of 160 VDUs 1n each telephone area. The projects area/reg1onal maintenance organisations. will also requ1re 3,000 printers- on average 50 Equipment in each telephone area. Together w1th BT will be taking over the maintenance Implementation processors, d1sc dnves and magnet1c tape respons1bil1tes for computer equipment used on Havmg agreed the pnnciples nationally Within drives the three large projects Will provide an ARSCC AND MOH. BT, the chosen method for Implementing the ideal launch-pad tor BT to develop 1ts expertise DARSCC: the VDUs used with ARSCC are policy 1s firstly to look at the maintenance and in computer servicing. supplied by Lynwood Scientific Developments repair tor equ1pment Installed on the largest of Ltd, and will become a responsibility of BT for - 29 Systems Ltd, who have proposed a phased handover of the first-line maintenance and repair to BT.

Maintenance and repair First-line maintenance is being arranged locally, with consolation between Regions and Areas determining the best method. It is essential that staff become expert in a range of peripherals so that restoration of service at a particular location can be accomplished 1n the majority of cases with one visit. It is planned that repair will be carried out at ARCs.

Training Maintenance training is being organised by BTTC Stone, and the first computer peripheral (printers and VDU) courses commenced in May 1983. As more equ1pment falls under BTs maintenance responsibility, necessary training courses will be provided.

The prospects BT has embarked on a course which aims to build on 1ts existing strengths of a nationwide maintenance and repair organisation and a highly-skilled work force. But we should not lose sight of the fact that this policy only opens up the option for BT to undertake this range of The Lynwood BETA Visual Display Terminal­ work. The extent to which BT actually takes it up typical of the equipment now being maintained and will depend - in the final analysis- on whether repaired by BT. DMOH: The MOH project calls for equipment or not it is economic to do it in-house. maintenance and repair from 1 June 1983. BT to be installed in every telephone area 1n the By demonstrating we can provide an equal, or is in discussion with Honeywell Information UK. Printers installed on this project are better, service than others at a low cost, we can Systems Ltd on the handover of maintenance supplied by Newbury Data Recording and are become largely self-sufficient in the field of responsibility for the1r equipment used on BT's responsibility for maintenance and repair ,--,mputer maintenance and build a platform for ARSCC. The target date for handover of first from the outset of installation. The remainder competitively maintaining other organisations' line maintenance for Honeywell supplied of the equipment located in areas on this computers in future. equipment is 1 January 1984. project will be supplied by Ferranti Computer (01-432 2877) 30 Proeress on inaplenaentinl the Repair Serviee Stratee~

by Denis Webb LES 6.1 Programme interlaced with the RSS programme. This has The Repair Service Strategy (RSS) was The 3-year implementation programme resulted in some RSCs being modernised 1n described in the Spring 1981 edition of MN. envisages one-quarter of Repair Serv1ce advance of implementing the RSS. This article describes the progress made Controls (RSC) converted by April 1983; three­ Each Reg1on has appointed an RSS Liaison towards its implementation in the last two quarters converted by April 1984 and complete Officer to help Areas unravel this complex years and reports on early experience of its RSS working by April 1985. Modernisation of s1tuat1on and provide practical assistance with operation. RSCs with ARSCC (described 1n MN21) and RLT the1r Implementation plans Quarterly meetmgs The main provisions of the RSS are to raise (described in MN20) is expected to be over a of RSS Liaison Officers are held with Inland HQ the quality of the Repair Serv1ce and establish a five year programme with completion in 1986/ to co-ordmate the nat1onal programme and sound basis for BT Inland Division to effectively 87. The table shows the national overall allocation of RSC equ1pment and systems. compete for maintenance work in a liberal1sed systems provisioning plan. Repair Serv1ce Staff have to adapt to changed telecommunications environment by: workmg pract1ces as the Strategy is introduced, • establishing a fully mtegrated repair serv1ce RSC MODERNISATION and for some th1s can mean up to two months directly accessible by our customers at all 82/3 83/4 84/5 85/6 86/7 training The followmg are the main features- times • after selection, new Customer Service • functionalising RSC duties into reception and ARSCC SYSTEMS 28 79 79 79 Officers (CSOs) undergo an 8-week training record work. and diagnostic testing and RLT SYSTEMS 6 20 65 132 133 period made up of 2-weeks field training, a 2- distnbut1on work week course at either Harrogate (BTNE) or • providing field technical support and additional Implementation of the RSS involves solving a Edinburgh House (BTL) engineering training fault clearing capabil1ty lot of Inter-related questions about the centres. followed by a further 4 weeks of field • modern1s1ng RSC equipment and facilit1es. availability of training places. RSC equipment training and accommodation; and for the conversion of • Senior Technicians (STs) in RSCs are now Agreement indirect reporting RSCs and the introduction of required to spend 13-weeks every year in the The two pnncipal unions to the agreement 24-hour working, '151' circuit and exchange 'field' on technical support and fault clearance (POEU and UCW) gained acceptance of the RSS remote alarm re-arrangements. So it is not work. A two wt!ek TETC course has been proposals at their respective 1981 Summer always feasible to introduce Simultaneously all provided for those STs who have been away conferences. After tidying up some points of features of the RSS at any one location. This has from such duties for more than 2 years and, m detail. and extending- for financial reasons­ led to the practice of makmg local progress consequence. may need updating on the the onginally proposed introductory period from within overall plans spanning, where necessary, latest customer equipment and field practices 2 to 3-years. the RSS 1mplementmg Circular the 3-year period. • existing RSC staff have to get used to team S1 E8203 was distributed 1n February 1982. An additional complication is that the RSC working because of the 'functionalising' of modernisation programme mvolvmg the work within the controls provision of RL T and ARSCC has become • the introduction of 24-hour working at - 31 selected RSCs has meant staff adJUSting their but where the RSS has been implemented they hours of work to prov1de cover in the now appreciate both the changed atmosphere Mierofiehe evenings, at nights and at weekends and the opportunity to concentrate on the • where ARSCC systems have been introduced diagnostic testing and fault distribution work of RSC staff and managers have had to adjust to RSCs. doeunaent using electronically produced dockets, and Experienced RSC staff are find1ng their processing information on VDU screens training course helpful for initiating their return ationfor • RSC managers must organise the new to periods of field duties, which gives more staffing arrangements to see that it is breadth to their work. introduced smoothly and remains effect1ve. A Because of the relatively mild Winter of 1982/ TXE4 series of one-day courses has been arranged 83 few RSCs were put to the test of having to to explain the RSS. Job conference courses deal with high fault report rates, but we are covering all aspects of the Repair Service have confident that those working with RSS will be by Ron Webb LES4.2.1 been provided at Horwood House College. able to cope much better than those without. Following field trials of the use of microfiche The real benefits are most evident at the few documentation in TXE4 (RD & A) exchanges it Progress RSCs that have introduced functional working has now been dec1ded to introduce microfiche In the first year, 40 RSCs, spread out over 22 of with ARSCC. Together these changes enable as an addition to the standard range of paper the 61 telephone areas, had introduced the RSC to retain control of the fault situation at copy held in exchanges. The provision is to be at functionalised RSS working. This number is all times and eliminate the frustrations and local discretion and Areas have been lower than that envisaged, but there is still a inefficiencies caused by manual fault handling approached to ascertain their initial good prospect of completing implementation in systems in periods of heavy fault reporting. requirements. the remaining two years. The groundwork for With liberalisation of the supply and When Area needs have been collated modernising the repair service has been done maintenance of customer apparatus in arrangements will be made for provision of the through successful trials of ARSCC and RL T prospect, the future for our repair service will be necessary readers, trolleys and microfiche. It is with some implementation systems in use. heavily dependent on its ability to respond to expected that supplies will become available Experience so far shows that the strategy is customer needs better than any other towards the end of 1983. well received by area management. repair staff competing organisation on both quality and cost A full description of microfiche and customers. criteria. documentation for TXE4 will appear in a later CSO trainees, including those selected from The Repair Service Strategy with its issue of Maintenance News. operating duties, are finding their training to be modernisation of RSCs will form a key element (01-432 2481) challenging and stimulating. On becoming part in BTs ability to improve the efficiency of its of an RSC team they are making a significant repair service and maximise its share of the impact on customer service at the fault maintenance market. reception stage of repair service work. It is heartening that a non-BT person- on 'Pre-strategy' RSC staff have come to accept recently being shown both pre-strategy and the new method of working, with its emphasis strategy-type RSCs remarked: "The strategy on team work, 1n what has been till now virtually works". an all male preserve. Some staff have had I am sure he is right. reservations about this aspect of the change, (01-432 2871) 32 Ernie's to lllanae f

by Adrian Frame LES4.2.4 must have baffled employees of Plessey Ltd (ex under consideration. But it is not all gloom and While abbreviations are outs1de the scope of Automatic Telephone and Electric Co), despondency- the mythical BT bookworms th1s article I sympathise w1th the correspondent bemused those concerned with Art1fic1al Traffic have produced wonderful tongue-wrapping (see LETTERS- Th1s 1ssue) who wishes to Equ1pment and infunated programmers of words like RERLO (Regional Equipment Repair know the meanmg of RWT and FNF. We have Automatic Test Equipment. Personally I'd Liaison Officer) and SPRET (Spare Plant grown accustomed to a world of abbrev1at1ons rather have TEA (Test Equipment Automatic) Returns) wh1ch are unique in spelling, meaning and acronyms- some good ones like NATO, but then I could be refemng to a Tunnel­ and pronunciation. LASER and ASLEF have passed mto everyday Emission Amplifier. You might th1nk that EAT Finally, recent re-organisation has placed language and are used by people who neither (Equipment, Automatic Testing) is better but sections of what was once THO into Inland know nor care about the precise significance of that could be confused with Employment Division Local Exchange Services, making us each letter. That does not 1nfer that the Appeal Tr1bunal or, in aviation, Expected IDLES- which some of our colleagues in the concepts of western mil1tary alliance, coherent Approach Time. field have suspected for a long time I light or walking to work are not understood. Being famil1ar with PAT. intimate with PAM (01-432 2805) The use of acronyms, good and bad, and wearing a d1rty MAC allows me to confuse proliferates in British Telecom and 1t would have and embarrass the unfortunates who are come as no surprise to learn of a group of BT inel1gible for membership of the Technical bookworms employed only to invent words and Jargon Club. When asked a tough question I can give new mean1ng to old ones. hide beh1nd an obscure acronym, secure in the Having spent fourteen years at school knowledge that the probability of someone else learning that ATE was the past tense of eat I knowing exactly what it means is very small, entered the Post Office confident that I knew all wh1le to adm1t ignorance risks being blackballed. there was to know about ATE. Glimpsing the This means that I don't have to know the word pnnted boldly in an Educational Pamphlet definition either, although in an emergency one my mouth would water at the thought of can always make up something with a fair spotted dick or some other delicacy. To be told chance of being right. that it referred to an indigestible collectiOn of The problem lies in the method by wh1ch Strowger or Crossbar equipment did noth1ng for acronyms are produced. All too often the my ego or stomach. Now fully conversant with "acronymicist" starts w1th the end product and Automatic Telephone Exchanges I would litter tends, because 1t's eas1er, to choose a word that my written work with ATE in the forlorn hope of at best sounds, and at worst is spelt like a word impressing the Training Officer and utter the already 1n use. He then racks his bra1n trying to hallowed syllables whenever it felt even make the letters signify words that apply, remotely appropriate. All this idiotic chatter however loosely, to the product or pmcedure 33 Teleeraph Transnaission- 'SCVF IN: 80V OUT'-Introduetion by Benny Goodman SSE 2.3.1 supplies requirement can be met at an outstation with SCVF (Single-channel voice-frequency) will • the use of lower voltages is more compatible only existing multiplexing equipment available. become the new standard for telegraph with present safety standards. Figure 2(b) demonstrates how circuit growth 1n transmission. Why introduce it now? The a Strowger exchange will be catered for using telex network is in the process of SCVF in the telex network new design multiplexing equ1pment. and a 12/ modernisation, including the replacement of The introduction of SCVF into the network 80V converter to interface the low voltage Strowger exchanges with stored-program coincides with the relaxation of the BT equipment to the exchange. control (SPC) exchanges. The traditional 80 monopoly on the supply of customer apparatus. volt signals are unsuitable for interfacing In the near future all new telex customers will Description modern exchange technology so an interface the network with SCVF, and existing In the forward signalling direction, the SCVF alternative had to be found. customers will have the option to if they so converter changes DC mark and space The method chosen is known as SCVF and choose. telegraph signals, mto two different frequencieS conveys information from a teleprinter over the The planning principle for introducing SCVF representmg the mark and space s1gnals. In the cable network and is much less affected by into a new SPC exchange area, and an existing reverse direct1on it converts a two different cable resistance- allowing the use of longer Strowger exchange area, is shown in figures frequencies, representing a mark and space, physical circuits. The system converts the DC 1(a) and 1 (b) respectively. into DC telegraph signals. The SCVF converter 'mark' and 'space' signals into suitably-spaced Figure 1 (a) shows that for a new SPC provides a method of simultaneous frequencies for 2-wire transmission over the exchange area, the Unit Telegraph (UT)54 is transmission at speeds of up to 300 bauds over cable. used to interface the exchange either directly or a 2-wire presented. unamplified circu1t. through a new design multiplex equipment. Table 1 summarises the parameters of all Advantages Existing customers will be provided with a UT55 three SCVF converters available for use on The advantages of replacing the 80V system prior to exchange change-over, allowing the telegraph circu1ts. It should be noted that the with SCVF can be summarised as follows. It: circuit to continue work1ng at SOV. When SCVF converter at the customer's end of the • reduces interference in an exchange required, a unique signal is transmitted from the circuit uses the reverse frequencies for environment that uses modern low voltage exchange to the UT55 in the customer's transmitting and receiving to that of the circuit technology in its design premises to initiate a permanent change-over to exchange-end SCVF converter. • reduces interference problems to other SCVF operation. The SCVF converters have a range of networks using the cable network Figure 1(b) shows how the wse of a UT56 will strappable options designed to cater for the • removes the baud speed restriction of SOV interface a new SCVF customer to an existing exchange signalling protocols, including sending signalling Strowger exchange. a permanent mark or space if the line fails, and • removes the distance restriction of 80V During the transitional stages, additional the ABS cond1tion. signalling arrangements may be met as shown in Figure 2. The line attenuation between two SCVF • cheaper and more efficient use of power Figure 2(a) shows how a customer's SCVF converters must not exceed 25dB, allow1ng a 34 EXCHANGE LINE CUSTOMER PREMISES IN STN OUT STN UT 55

Existing UT54 TP 12V P I · SCVF 12V ~----~------h~y_s_ic_a~p_a_lr______~------~r-~-~ /~ -D NewTP SPC SCVF Telex New des1gn SCVF SCVF Exch 1-----...;.---o - o----11 -DI----- NewTP Multiplex system \ SCVF \ F1gure 1a. For SPC exchange areas. \~ Existmg ~~ TP UT55 Existing sov Existing Strowger multiplex system TP

Telex 1----.;------i------s_c_v_F_·;---o _ o----11 -DI----sc_v_F_ NewTP Exch Physical pair

Figure 7b. For strowger exchange areas: F1gure 1. SCVF in the telex network- planning pnnCiple

SPC 12V Ex1sting Existing multiplex system TP Telex Exch. 0- 0---11 -DI---- NewTP

F1gure 2a. For SPC exchange areas UT56 UT54

SCVF • o----11 -o---- NewTP

Telex sov Existing SCVF : Exch o----11 -o,______NewTP . multiplex system . UT56 Figure 2b. For Strowger exchange areas:

: Figure 2. SCVF in the telex network- transitional additional configurations 35 Unit Max. Telegraph Frequencies TX RX baud Equipment No. Type Transmit (CH 1I Receive (CH2) level level D.C. Interface speed practice

54 B 980Hz 1650Hz 13d Bm <38 ±12V 4 wire 300 TEP 1180Hz 1850Hz fixed dBm interference on cable networks, and prov1de a 55 A 1650Hz 980Hz 13dBm <38 ±12V 4 w1re -300 more suitable Interface between modern telex or Case 1850Hz 1180Hz f1xed dBm ±80V 2 wire -110 machines and modern telex exchanges. It will also enhance the telegraph private circu1t 56 B 980Hz 1650Hz 13dBm <38 ±80V 2 wire 110 62 type network by providing more flexibility in routing 1180Hz 1850Hz fixed dBm mcuits. SCVF will also Simplify the connection of telex customers in rural locations. Table 1 Unit Telegraph S1gnal Converters for Telex (0 1-432 2239)

5dB margin for maintenance and installation A plug and socket arrangement will be used to tolerances, giving a max1mum tolerable terminate the l1ne in customers' premises. The attenuation of 30dB. socket will include contacts which connect a If a line attenuation exceeds 25dB, then the 15Kohm resistor and diode 1n senes across the circuit can be amplified by using audio 4-wire line when the plug is removed. Th1s facil1ty amplifiers, or by using a mcuit in a telephony enables the test desk or transmission term1nal multiplexer system. engineer to more readily identify l1ne faults The SCVF converter 1s capable of supplying without the need for an eng1neer at the line wetting current and this arrangement will be customers' prem1ses. used on all unamplif1ed circuits. In the case of The telegraph transmission engineer will amplified circuits, the method of line wetting adapt quite readily to new SCVF transm1ss1on will be decided by the circuit design group systems because of the s1milarity in principle working to Engineering Performance between SCVF and MCVF (multi channel-voice Specification (EPS) 21. frequency). New test equ1pment and test facilities will be provided at transmission Maintenance terminals enabling SCVF faults to be dealt with The use of SCVF 1n the network will introduce a quickly and efficiently. new facet to telex circuit testing in the test BTTC will be providing the training for SCVF, room, reaching out to the field maintenance and this will be made available to staff by Area officer (FMO) traditionally involved with BOV DC Training Officers. line transmission systems. Test equipment designed for testing SCVF Benefits circuits will be prov1ded in the test room and The introduction of SCVF into the telegraph similar facilities will be made available to FMO's. network, replacing 80 volts, will reduce 36 On refleetion .. Here we look back to MN12 (Autumn 77) and invite some of the authors, or their successors, to comment on their articles Don Littlemore RA 1 .5, updates us on engineers. particularly, area organisation. Over the years­ Electronic PABXs. The past five years or so have also seen the in spite of some successful attempts to Since the range of first generation electronic emergence of some new Field Support Units rationalise files and so on- it became difficult to PABXs was described in MN12, the population (FSUs) set up specifically to deal with field control growth of the paper mountain. has increased to around 1000 systems problems which cannot be anticipated by the At peaks there were 180,000 files, and 30 nationally, the vast majonty being stored normal training, documentation and diagnostic million pages were be1ng issued each year­ program control (SPC) types. Products such as packages. Their role is proving essential for the including one maintenance Tl every day, on the Plessey PDX and GEC SL-1 have developed maintenance of computer-type equipment. average. These disadvantages, combined with larger brothers with greater call processing especially where software plays such a part in the setting up of separate Divisions on the powers. On the other hand the Philips EBX 8000 the operation of systems. formation of British Telecom, led to the now has a smaller brother with a simplified Our approach to electronic PABXs has conclusion that a single centralised system of configuration for the 'low end' of the market enabled us to establish a clear lead over instructions was no longer appropriate. Instead, Also, during that time we have seen BT's own organisations which very soon might be able to separate systems related to Divisional maJor venture into SPC PABXs with the firm compete on equal terms with BT for their requirements should be developed. establishment of Monarch and Regent in the maintenance. Systems which we looked at as As Inland Division had responsibility for more market place (MNs 15 and 20). PABXs in Isolation a few years ago, are now than 80 per cent of Tis- and 95 per cent of files The next generation of systems are already becoming the hub of the 'business -the development of a new system had to be beginning to appear: these new systems communications systems' of the future and carefully planned. As an interim measure, the Tl offering an increased range of facilities while with efficient collection of maintenance cost system has been continued by the issue of being more compact and with a lower power data, we will have information to stand us in Inland Division Tis. The new system- known as consumption. The ability to Interface with dig1tal good stead to cope with further generations of the Inland Division Information System (I DIS)­ networks (including System X), and the facility electronic PABXs. is now well advanced and will be operating later to combine data terminal and telephony (01-432 2198) this year I DIS will allow flexibility of functions on a single port will feature heavily in presentation- such as booklets or maintenance new systems. manuals- to meet users' needs. Distribution of MN12 talked of the changing skills of PABX copies will be determined locally. staff, and many more staff are by now aware From Tl's to lOIS From the stat1stics already quoted, it is that modern products do offer interest and a Brian Grover updates readers on the future of obvious that it will take time and effort to bnng challenge. The increased use of private the Tl system. I DIS to completion, but the a1ms are clarity, ease networks (perhaps with 1nter-reg1ster signalling The Tl system was introduced in 1972 to bring of reference and generally to avoid overloading capabilities), the extra complication of customer together the many different series of busy users with unwanted detail. data management programs, and the new instructions (including Els) which had operated Further information on the operation of \DIS concepts of digital transmission with all their in the Post Office prior to the change to will be published as the system 1s developed. attendant advantages and pitfalls are JUSt a few Corporation status. The system had many Brian Grover IDP5.1.2 of the new problems tackled dally by our advantages, but it was linked to business and, (01-357 2914) 37 Letters

Abbreviations are fine, but ... of a fault was confirmed, the cause was not Ted Lindfield replies Maintenance News IS read with mterest by definitely located Tl E13 80013, para 31, refers. We have tried the 1dea of translating spare C some BT personnel unfamiliar w1th the fmer I hope this helps. - Editor. digits to a telephone, it proved to be time points of exchange maintenance and its consuming and the time spent was out of associated jargon. At least one regular reader proportion to the number of faults located and finds his interest 1n technical art1cles somewhat Improved Transit performance cleared We were also unhappy in charging frustrated by the use of initials, doubtless weH DC White of BTNW comments on the article 1n customers for the mis-routed calls, if non understood by mamtenance staff. issue 21. Whilst agreeing with most of the metering equipment is used, insufficient time is For instance- David Memory's article article I must take exception to the paragraph: available for tracing before forced release takes 'Maintenance after the Monopoly' uses two Incorrect C digits. place. abbreviations: RWT and FNF, without Even though the fault may not be in the Translating to a spare level or a telephone explanation. incoming RT it is still a 'system' fault and as inhibits repeat attempt, therefore the call must May I request that, for future articles, such attempts should be made to clear it. fail. Our method allows repeat attempt and the abbreviations are written out in full the first In the majority of cases the outgoing end or call will most probably mature satisfactonly. time, so that we non-engineers can have a TSC staff will be oblivious to the fault. If, The objective we set out to achieve was to better appreciation of what is being discussed? therefore, the source of the call can be remove alarm conditions which did not relate to L. Hemming, MSP5 OA6.2.1.2 determined the prospect of clearing the fault is faults within the RT. Those alarms remaining (London Materials SCience Section) vastly improved. Instead of just providing a CO would be meaningful and a worthwhile fault -That MN(Maintenance News) 1s read oy non­ signal for incorrect C digits it is suggested that a diagnosis could be made, ie genuine eqwpment engineers is flattering but our primary aim is to 2 digit translation is used to route the call to a faults stand out when alarms due to network communicate with maintenance staff. The point spare level. By checking the number of calls on problems and customer errors are removed made by my OA(Ouality Assurance) this level 'hard' faults are easily indentified. A Regarding the outlet testing, our correspondent is, however, taken seriously, special faults-type telephone is now substituted investigations revealed a number of register despite my colleague Adrian Frame's light­ for the spare level R/S, calls answered and the hunter outlet faults which are difficult to locate. hearted reminder of this common pitfall (see source determined. BTNWs method should be well worth adopting. 'ERNIE's to blame' in this issue). To make An additional aid that we have found useful is The reference to Tl E5H0112, should be amends, RWT and FNF are two of the most an 0/L tester for the AC11 register hunters. E6H0112. used abbreviations in maintenance and refer to Bas1cally this uses the call sender of the TRT TS02/SE/1 .1 categories of fault 'clearance' (something of a 118 to pass calls over the RH mult. I will be 0273 201245 misnomer I feel). RWT means 'right when pleased to supply details to anyone interested. tested'-that the fault was not observed on the BTNW first retest following the fault report. FNF- fault S2232 not found- means that although the presence (061-863 7552) 38 Cut out this Index page and fix it to page 12 of MN Index, Issue 1, 1981 ~d~wrlssues2Q;;------l

1 Issue page Issue page Coin boxes General I New housings for PCO's 22 22 How computers keep their cool 20 6 I Customers' apparatus SCROLE's roles 21 6 I Regent call connect system 20 7 Circuit multiplication using TASI 'E' 21 7 I Harmony loudspeaking unit 21 1 Maintenance after the monopoly 21 11 I Ambassador ESS 22 20 Computer maintenance in BT 22 29 Building services- control for the 80's 22 5 I Exchanges- general Local lines 1 Register translator 14 20 11 1 Introducing regional service improvement centres (RSIC) 20 26 Improvement plan for overhead network 20 3 BTNEs RSIC (for TXKI) 21 2 New cable alarm saves money 20 24 An approach to improved transit performance 21 20 Blackspot analysis- an areas view 21 18 Network improvement using MAC 21 25 New announcer for SALT 21 33 MAC Recognising unrecognisables 22 3 Undercarpet cable 22 11 Exchanges- digital (System XI TXD Repair Service Controls Operations and maintenance centres 22 15 New generation test equipment for the fault repair service 20 17 Modernising repair service controls using computers 21 27 Exchanges- International Direct Dialling Repair Service Strategy- progress 22 31 Alarm handling at Mondial House 21 13 Increased dialled access to Eire 21 15 Safety NITE shift, new tariff equipment 22 9 Lightning protection of modern equipment 22 24 Exchanges- Strowger TXS Special services Microphonic noise in TXS 22 Testing SSAC 15 Private Circuits at TMCCS 20 1 Special services maintenance 20 4 Exchanges- TXE 4/4A The Irish connection 20 10 Close encounters of the 4A kind 20 14 Faster RATES for private circuits 20 20 Tester 291 A- a network analyser for TXE4 exchanges 21 4 Special service managers 21 24 New printout analysis for TXE4 (RD)- PATE 4 21 22 Kilostream- fault handling procedures 22 26 TXE4 present performance and future targets 22 18 Microfiche documentation for TXE4 22 32 Telegraphs I SCVF in: 80v out 22 34 1 Equipment repair I Automatic testing methods 20 21 Training New electronic work bench 20 25 A man's home is his college 22 7 I New fault label- repair care 21 36 Transmission- digital I Digital transmission- coded mark inversion 20 5

L-~------~ ------J 39

If you have a contribution to offer to Maintenance News other than a letter to the editor, please forward it through normal channels to the Maintenance News agent for your Region or Telecommunications Board. The list is shown below. The Editor cannot publish anything to do with current awards suggestions, neither can he be held responsible for technical inaccuracies in authors' submitted text. Send ~our eontrillutions to.. EASTERN Mr R F Lambert S1 .1.1 020689588 INTERNATIONAL Mr D A Bardouleau IL3.3.3.3 01-936 3368 LONDON Mr E Jones SM1.1 01-587 8000x7489 MIDLAND Mr C R Webbley PG2 021-262 4383 NORTH EAST MrR Mundy S3.1 .1 0532 467 529 N IRELAND Mr J McLarnon Sv2.3 0232 31594 NORTH WEST Mr A Bunnis S2 .1 061-863 7458 SCOTLAND Mr P McElroy S1 .4.1 .1 031-222 2390 SOUTH EAST Mr R Bayfield SM1 0273 201 218 SOUTHWEST MrJ 0 West Sv1.3 0272 295337 WALES & MARCHES Mr E H Slight S3.2.2 0222 391456 British TELECOfr\

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