No.1 - Summer 1980 'Our Standards Are Highest' -DE " You may think it is strange that at INF a time when many things are being cut that we should initiate this engineering The Quarterly For BBC Engineering Staff bulletin but for a very small cost every year it should be able to contribute considerably to keeping us all in touch with what is going on in BBCEngineering. Some of you may well be pleasantly BBC Showing atIBC surprised at the range of development Major that isgoing on in BBC Engineering now, today. The BBC will take an important place at the International With technology developing as Broadcasting Convention in Brighton this year. rapidly as it does today I am very proud No less than seventeen conference papers will be read by BBC to be able to boast that engineers in the engineers and there is to be a major exhibition stand to show off more BBC are not just following close behind than a dozen novel engineering developments from Research and Designs the technological bandwagon but are Department. amongst those who are in the front All the products on show can be FM transmitter equipment and compact, pulling it along. licensed for manufacturing by private microprocessor-controlled equipment But the cuts in our expenditure industry or have already been licensed that will generate logos and have been on all our minds over the last and need to be shown off to potential captions.. few months and the repercussions will There will also be a demonstration overseas customers. At the moment continue to affect us for a long time. We prod tiet licences draw in some £65,000 of processing audio signals using a COPAS (Computer Processing of Audio have to give up 130 posts in the a year but we aim to increase that as Engineering Division from a total staff much as possible. Signals) system in which spectrum The equipment on the stand wIll shaping, compression, limiting and other of some 7,000. As well as the reduction include novel equipment from Research audio processes are all controlled by a in staff we are going to suffer much Department for electronic preparation bit-slice microprocessor working on tighter budgetry control, but as engineers of Television Graphics and ACE digital signals. we are thoroughly used to the practice (Advanced Conversion Equipment), Outside the exhibition hall will be of tailoring our system to the budget the first four-field digital standards CMCCR 2, the BBC's new Colour that is available. converter and the first to be virtually Mobile Central Control Room. It has transparent in operation. sides that expand to 4th metres width, Other developments on show wlll opening to give a spacious production include NICAM, the digital sound unit that will handle 25 vision sources distribution system, high-quality Band II and includes a stack of 34 monitors. 405 Ends, Self-Help Begins On May 20th, the Home Secretary 1984. Service Planning Section at announced the phased closure of the Research Department cannot yet 405-line television service, authorisation anticipate the number of Phase III for a further stage of relay station stations that will be required but building and also signalled the start of a feel it may be as many as 500. scheme for 'self-help transmitters'. These will be built at the same rate of 70 a year. The closure of the 405-line trans- Bryce McCrirrick mitting stations will be spread over a In the 'self.help' scheme, approval . Director of Engineering period of five years between the will be given to small remote beginning of 1982 and the end of.l986. communities to set up and run Despite these cuts in effort and money our technical standards will not The 39 BBC stations to be closed in their own stations. Broadcasters 1982 are in areas where there is almost will do the basic planning and will fall. As broadcasting engineers we will complete UHF coverage. The closure ensure that the transmitters are continue to lead the field in Research programme will be co-ordinated with the integrated into the network. and Development and our operational IBA so that transmitters in the same area Then when a station comes into standards will likewise continue to set will be closed at the same time. These operation the broadcasters will and example to broadcasters the world are the key points from the check that it is not causing inter- over. announcement: ference to existing viewers in the Some of the equipment that has area. When this has been done the recently gone in service shows just how . Phase III, the next phase of UHF BBC engineers are setting even higher relay station building, will follow Home Office will issue a licence on after the present Phase II prog- for five years operation at a cost standards. The new digital standards ramme has been completed. With of around.£100. converter at Television Centre has 200 Phase II stations still to be proved so efficient that some people built at the rate of 70 stations a ask whether programmes have in fact year, Phase III should begin during Continued on page 2 Continued on back page 'Eng. Inf ' Summer 1980 - Page I (contd. from page 1) j Simple Self Help ! ! 1-11...1. Most of these stations are expected to use commercial yagi receiving and transmitting aerials and commercial . The amplifiers will be similar to those being used at present for wired distribution systems. The power of each station will obviously depend on the area it has to serve but will have to be care- fully planned to avoid interaction with other stations on the same or adjacent channels. Split receive/transmit sites may be necessary in some cases. Most of the stations should be active deflectors which A self-help system could be just as simple as this receive and transmit on the same channel 405-line Stations closing during 1982 but some stations may need to use in order to avoid possible Abergavenny Cambridge Hungerford Okehampton interference. Aldeburgh Campbeltown Kendal Oxford Ayr Canterbury So far there have been about 40 Kilkeel Perth Ballachulish Cardigan Kinlochleven Port Ellen requests to operate 'self-help' stations Ballycastle Cannarthen Llanelli Scarborough mainly from remote communities in Bedford Church down Hill Maddybenny More Scilly Isles Scotland. So, it is difficult to assess Belmont Dundee Law Marlborough Sheffield how many 'self-help' stations will be put Bexhill Ffestiniog Newhaven Swindon in service but estimates vary from 200 Bodmin Girvan Northampton Ventnor to 500 stations. Bude Hereford

ABOUT 'ENG. INF'. Radio With Data As Well You can call it what you like but if you want to use our name you should Research Department is developing The VHF/FM system is capable of pronounce it 'Enj. Inff'. We are aiming ways of sending extra, inaudible signals supporting a data rate of 1200 bits per at the technical people in the BBC and with radio broadcasts. Using these second using a biphase signallingrate of we hope it will give a wider view of what signals tuning could become automatic 2400 baud. The BBChas shown that is going on in BBCEngineering. and the radio set of the future could these signals could be very effectively We would welcome your views on have an electronic display indicating the placed on a of 57kHz. Test this first edition and we will welcome name of the network, telling the time or transmissions have been broadcast on contributions from you for future giving the latest news headlines. There Radio 4 and Radio London from editions. If you are too busy to put pen are two systems, one for VHF/FM and Wrotham. to paper, then just ring BH (London) another for MF /LF radio. The MF /LF The VHF system can carry very 5432/5433 and let us know what you system is being pursued only by the much more data than the medium/long have been doing. BBC. It phase-modulates the radio wave system and as well as international We will sort out the protocol of carrier wave at 50 hertz using digital discussion on standards there will have ensuring that any stories we print have biphase modulation. The data rate is to be considerable discussion with the been checked with the right people so 25 bits per second and experimental receiver industry before the system you can feel free to pick up the transmissions have already been could go into use. telephone anytime you like. It may b/' broadcast from Droitwich, Radio 4. that some of your achievements deserv much wider coverage in magazines JOIN IN THE EXPERIMENT outside the BBC. We can see to that too Subcarrier tests are already under- Volunteers will have to complete a if the story and the time are right. way at Wrotham and Research special form so if you can listen to This edition was edited and Department want volunteers who will Radio 4 from Wrotham and would prepared by David Allonby, Gwyn listen critically to VHF at home or in like to join in the trials, telephone EID Morgan, Lynne Prop and Amanda their cars and report their comments. on BH 2921 for a form. Tucker. 'Digital TK Within FiveYears' -Says Sanders

'We can expect to see all-digital second to produce a single 625-line or ever the signal falls below 12.5% of peak telecine machines on the market within 525-line sequential output which then white. the next five years but all-digitalcameras is digitally stored. The information in But broadcast quality digital will have to wait for the nineties', says the field store is reordered and read out cameras will have to wait. Richard Richard Sanders of Research to provide conventional 625/50 or Sanders says, 'lightweight camera heads Department in an SMPTE Conference 525/60 interlaced . using economical analogue LSI signal paper. Dark areas of the picture must be processing cannot be matched by digital His team have already developed an coded to ll-bit sample accuracy. The circuits which need more space and all-digital telecine which produces 'an team have devised a practical alternative consume a great deal more power. For exceptionally clear and uniform picture'. to a fullll-bit ADC by providing a second example, to correct for element-to- The sensor is a 1024 element linear 8-bit ADC with its signal pre-amplified element sensitivity variation in a sensor array which scans the fIlm image by a factor of 8. The second ADC array would need a complete field- sequentially at 24 or 25 frames per contributes three additional bits when- store for each sensor', Page 2 . 'Eng. In! ' Summer 1980 Faster News Through Bush EDS External Services now distribute scripts of news stories, talks and features (about 30 million a year), electronically to more than 200 outlets in Bush House. Staff in the 38 different language sections no longer have to wait for the scripts to be copied and delivered by hand. Now, they can get their stories in seconds from a VDU or a printer in their office. At the heart of the Electronic Distribution System are two General Automation 16/440 mini-processors, operating in parallel. If there is a fault a complete standby system takes over immediately. Each processor is associated with a 2-megabyte fixed disc and 24-megabyte disc-pack drive. New material entered each day is dumped onto a magnetic tape and later transferred to microfiche EDS VDU's in Bush House newsroom for archival storage. to 15 'pages' on a VDU with each page Each of the 137 VDU's distributed holding up to 2,048 characters. around the building can undertake full Ken Clayson, ManagerEng. (EDS), text editing, but only those in the news, said, 'The system is saving an enormous talks and features areas are free to amend amount of time and paper, and it lets us the stories in the central store. Hard make far wider use of the material we copies can be demanded from 85 prepare. For the first time, everyone of medium speed (120 c.p.s.) 'Lear Siegler the broadcasting sections at Bush 200' printers and 36 low speed (lOc.p.s.) has access to all the scripts of the talks Transtel printers strategically placed and features that are prepared here. In amongst the offices of the different the days when we relied entirely on sections. paper, that was just not possible'. As well as the short news stories, The system was built by ITT the system can accommodate individual Business Systems to a specification set talks of up to 5,000 words (a half-hour by S.C.P.D. after considerable broadcast). A single story can take up discussion with potential users. Ken Clayson, Kevin Synott at E.D.S. BBC Rays, in Mirror, Stop Cars On June 5 the Daily Mirror accused So far there has been no indication The Daily Mirror were not the the BBC of causing traffic chaos on the that the units were either faulty or had only paper to take up the story, as the A45. In a page 3 story headed 'Blank been poorly installed but the AA and the result of their article an alarming report Blink Every Trip' the Mirror alleged that manufacturers are still investigating the followed in the Birmingham Post. This the BBC's Daventry shortwave trans- problem. And we have said that they said, 'the electronic equipment on the missions were putting electronic ignition can carry out any tests they want to on cars was affected by the BBC's high systems out of action. As you might site at Daventry. frequency low MHztransmission' -what- expect the Mirror was exaggerating more ever that means. than a little. Apparently, over a three month period two cars, one an ancient Cortina and the other a Scimitar, had broken down on the A45 near our Daventry transmitting station. Both cars used the - same type of ignition system. The AA found that the first car started and ran normally after it had been towed some distance away from the station. The second car responded to the same treatment. Both cars used an ignition system in which light from a LED is interrupted to operate a photo- conductive transistor which triggers the ignition and both the AA and the manufacturers themselves feel confident that our transmission did not cause the breakdown.

'Eng. In! ' Summer 1980 - Page 3 -.....\,.. Ii \,

Camera in Whispering Gallery Dave Hunter on Camera 5 outside Buckin!;Jlam P; Major OB For Queen ~ On Tuesday 15th July there was a like this. Service of Thanksgiving at St. Pauls as Frank Hughes, Assistant Head of part of the celebrations for the Queen Engineering Television OB's who Mother's 80th birthday. A major BBC co-ordinated the engineering planning TV outside broadcast using 24 television said, 'The experience of the Jubilee cameras followed the Royal procession broadcast in 1977 helped considerably from Buckingham Palace and covered in planning the coverage of this the ceremony in the Cathedral. ceremonial programme. Apart from Producer, Mike Lumley said, 'The CMCCR 1 at St. Pauls from which the Jubilee broadcasts in 1977 were our entire OB was directed, five other starting point in planning the OB. The mobile control rooms at St. Pauls were requirements were very similar and once used for operational cameras, radio-links again we were able to give viewers a and video-tape inserts. In the Cathedral spectacular view of the nave from a additional lighting for television was set camera at the apex of the dome', under the direction of Engineering Man. Overall direction for the broadcast ager, John Wilson.' centred on the BBC's Colour Mobile There were two mobile control Central Control Room (CMCCR 1), a rooms along the processional route as unit designed for use at major occasions well as a single camera installed high up CMCR at Admiralty Arch 25 year old Wrotham gets Major Re-build On 2 May 1980, the Wrotham VHF/FM transmitting station celebrated J~ its 25th Anniversary. In 1966 it was the -.- first station to go stereo and in 1972 the l first to have a pcm link. Now it will be the first to be modernised. Wrotham will get a new aerial and -.. new transmitting equipment. The new aerial will introduce a vertical component into the transmission to improve reception on portable and car radios, which normally use vertical aerials. The work should be finished by 1981. \ .Far left: Wrotham mast as now. , Near left: lan Blanthorn, AEIC CP, and STM Derek Mann in Tx hall, Page 4 'HlIg. fill' Summer 1980 "

alace Links at House 'Compact' links hut at NZ house ,loth er's Thanksgiving on top of New Zealand House. The first The signals from the CMCR's at the of these was one of the BBC's new Palace and Admiralty Arch were radio- Type 5 CMCR's equipped on this linked to New Zealand House and from occasion with seven cameras. Three of there they were fed on to St. Pauls. these cameras covered the Royal Party At S1. Pauls thirteen cameras as they prepared to leave Buckingham covered the scene outside and inside the Palace, while the remaining four Cathedral. One of these on a building followed the start of the procession as it overlooking the West Door was linked left the Palace and travelled along the by radio to its control van. Mall. Six cameras were installed in the One advantage of the Type 5 units Nave and Chancel of the Cathedral, but is that the cameras use tri-ax cables the most spectacular shot of the Nave which are much smaller in diameter was provided by a camera mounted than the multi-core cables previously above a peep hole in the very top of the ~cessary. Tri-ax cables can more easily dome. This camera looked straight __ _ pulled through the ducts under the down onto the congregation 275 feet road. Along the Mall and on Adriliralty below. The same camera was also used Arch four more cameras covered the outside on the Golden Gallery to give a procession on its way to the Cathedral. bird's eye view along Ludgate Hill. Peephole in the dome New Continuity Suite in BH Basement . Radio has a new stereo continuity ..,..

studio in the basement of Broadcasting . . House and Radio 3 are now in . "'~ - occupation. Continuity 'B8' has been [1 . installed in double quick time by S.C.P.D. They wanted the new suite in a hurry because they needed to release one of the six suites on the first floor for staff training. Amongst the novel equipment that has gone into the studio are some modern voltage controlled amplifiers from the new Designs Department 'Maxicon' system and an all solid-state monitoring system that does away with the need for relays. T.O., John Morgan, and Jeff Bottom, S.C.P.D. with installation team in B8. 'Eng. Inf. ' Summer 1980 . Page 5 More Legs for PCM The BBCbegan stereo broadcasting but with only two services. using the Zenith - G.E. system in the This year extra legsare being added mid-sixties on the Third Programme. to the PCM distribution system. One leg Using analogue links the service was goes via Peterborough to Tacolneston carried by Wrotham, Sutton Coldfield and will make the temporary and Holme Moss. In 1972 the analogue Tacolneston feed redundant. Another links were replaced by links carrying the goes down to Rowridge. The Scottish signal in PCM. Again Wrotham, Sutton route is being extended to Meldrum this Coldfield and Holme Moss were the first autumn and will reach Rosemarkie early to be reached, but this time with three next year. stereo channels. The PCM link system Londonderry, the only vhf station carries 13 separate sound channels six in Northern Ireland not radiating stereo of which supply the three stereo services. will receive its feed next year, but the The extension of the PCM system western and northern parts of Scotland to Kirk o'Shotts, Wenvoe and Divis left and the west and sound of England will holes in the coverage in East Anglia, have to wait until 1984/5. North and West Wales, South and South- The PCM distribution system was West England, Northern Scotland and extended to Peterborough onll th July Londonderry. Some of these were filled bringing another 125,000 people in the by using analogue links: one link went city of Peterborough within the reach of from Wrotham to Tacolneston, another high-quality stereo radio. _ The BBC received Wenvoe and fed North Hessary PCM network, now some 8 years old, Tor. In each one only two of the three is still unequalled anywhere else in the services could be carried. Rowridge world. operated by direct pickup of Wrotham, PCM coder in London Control Room. Digits Catch On In Local Radio Energy - nearing Energy savers ETD have bought a Local Radio engineers are putting studio, 3G, follow a similar pattern each second-hand milk float to cut the petrol digital techniques to work for themselves day so the appropriate code-groups are bills for carrying goods around the and saving time and money as a result. simply sent up the line from a conven- grounds. It won't help sleepy students Des Richards, was with LR head- tional recording on a cartridge. though; there will be less now to quarters when he developed an David Cox has solved a similar wake them up in the mornings. automatic system for directing taped problem for Radio Solent. They have reports from London to specific local an unattended studio at the Portsmouth Radio Newcastle radio stations. Guildhall which also acts as a common The taped reports are sent along the f~d point for Post Office lines from the Radio Newcastle is extending its permanent Local Radio Distribution Anglican Cathedral, the NavalDockyard, coverage to offset the effects of the cut System and all reports are received at all three OB local ends and the Chichester in Radio 4 local news bulletins later this stations, but not necessarily recorded. unattended studio. The lines feed into year. Northern Northumberland and an Previously, it was necessary to warn the the Guildhall studio and from there area as far north as Berwick-on-Twe individual stations that they would have they are switched, as need be, to a would have lost all trace of local ne ~ to record specific items and they would common music circuit between when the VHF Radio 4 opt-outs were have to start the recorder manually and Portsmouth and the Radio Solent ended but now Radio Newcastle is going listen out for the finish. operations room. All the necessary to cover the area when a new vhf The digital system makes the process switching at Portsmouth can now be channel 94.5MHz at the Chatton trans- automatic. It sends a M-bit signal along done automatically from Southampton mitting station goes into service in the the music circuit at the start and finish thanks to a digital sig!1allingsystem. Autumn of 1981. of each item. The signal can convey up The digital signalsare sent along the to 16 commands but at the moment it is two-wire control-line between simply used to switch-on and switch-off Portsmouth and Southampton. The Radio Leicester a tape machine at each station. equipment at Southampton sends an The signal is made up from an 8-bit ll-bit digital FSK code to Portsmouth Radio Leicester is being allowed framing code, followed by an 8-bit which can repFesent up to 35 different to change its mf frequency from 1584kHz 'order' or command code followed by commands. The data receiver at the (189 metres) to 837kHz (358 metres). 48-bits which represent individual Portsmouth end constantly monitors As about 25% of the receivers on the stations. the line but is immune to the market are not able to tune to 1584kHz Each station is identified by a single programme cueing and talk-back signals and as daytime propagation of this pair of bits in a specific location in the that share the same circuit. frequency meant that certain highly 48-bit group. The state of each bit-pair populated parts of the county, between indicates whether the station should Local Radio Goes Stereo Loughborough and Coalville, did not get obey the command or ignore it. an adequate service.,the lower frequency Code transmission units have been Radio Lincolnshire and Radio Norfolk, should help them get a much bigger installed in Studio 3D and in the which come into service later this year, audience. However, because of the Parliamentary Unit in Bridge Street. will be the first two BBC local radio higher level of interference on 837kHz, Regular contributions from another stations to,go stereo. coverage after dusk will be worse. Page 6 - 'Eng. Inf .Summer 1980 RDAhead in Satellite Broadcasting The urgent need to clarify the UK 2.4 metre strategy on direct satellite broadcasting Multi-polarization . has increased the importance of some Receiving Dis~ at R.D key experiments recently carried out by the BBC. for OTS Research Department has been investigating the separate technologies of and satellite broad- casting for several years. In addition to playing a leading part in the preparatory studies for the 1977Geneva Broadcasting Conference (through Home Office and EBU study and planning groups) Research engineers conducted the first experiments in PAL television trans- mission by digital methods through an I' Intelsat satellite. In May 1976, in collaboration with the British Post tests with the Post Office used the OTS 'with two digitally-encoded sound signals, Office they sent sound and television satellite to transmit two independent thus proving that either stereo sound or signals from Designs Department in television signals and six high-quality . two separate sound channels could .ondon to the Post Office GoonhiIly audio signals. The two television accompany the television signal in Jowns earth station. There they were channels were transmitted with satellite broadcasting. digitally encoded as a 60 Mbitfs package different polarisations but a common Work on satellite technology is still to include a television signal, six high- frequency. The test showed that the continuing at Research Department and quality sound signals and error separation between the two channels now that our proposals for programming protection, and sent to the Indian Ocean was perfectly satisfactory for digital satellite tests have been announced by satellite and back. In spite of the television transmissions. In collaboration Robin Scott, D.M.D.Tel., the discussion elevation of this satellite being low from with the French ground station at on satellite broadcasting is gaining Goonhilly, causing a poor signal-to-noise Bercany it was possible to trap about momentum. We have proposed that we ratio and relatively high error rates due half a second of television signal in an should take up two of the five channels to atmospheric absorption, the system earth satellite loop to demonstrate that that are allocated for satellite broadcast- operated with complete success. The the digital signal could be re-transmitted ing in Britain, one for Pay Television satellite transponder normally handles many times with no loss of quality. and the other for a service to provide frequency-modulated analogue signals More recent development work the best programmes from BBC 1 and and it was possible to compare analogue has used the OTS and an earth terminal BBC 2. Satellite broadcasting would and digital formats: the digital signal at Research Department. We designed instantly provid~ a national service. gave better overall results. It was the and built a solid-state preamplifier and Unlike a terrestrial network, a suitably- first time that the Post Office digital receiver to operate with a 2.4 metre dish stationed satellite can 'see' almost every terminal equipment had handled actual aerial. Experiments using this equipment part of Britain and, therefore, signals rather than laboratory have shown that it is possible to broad- television could be made available to test number sequences. cast a frequency-modulated signal which the whole population of Britain over- Then in February 1979 further comprises a PAL vision signal together night.

New HETD to Review Courses Dr. Alun Owen the new HETD Every BBC engineer and technical operator spends some time at Wood Swansea. In 1969 he became an Norton and if the new Head, Dr. Alun Automation Development Engineer with Owen, has his way we could be paying the British Steel Corporation. Then more visits there. He believes that train- from 1970 to 1974 he worked in the ing is a vital element in the BBC'soverall Ministry of Defence and roseto the Rank technical strategy and should be continu- of Lieutenant Commander R.N. From ous throughout an individual's career. 1975 until he took up his newappoint- With this in mind he hopes to provide ment he was Staff Tutor in Technology more courses for staff at all levels. in the South West region of the Open Dr. Owen, who took over from University. Harry Henderson as Head of Engineering Dr. Owen says, 'I want to review Training Department on 21st April this the current statutary courses to make year, has experience of other areas of the sure they are in line with today's needs BBC. He joined the BBC in 1963 after in the output directorates and I would getting adegree in ElectronicEngineering like to get recognition by the Technical at University College Bangor. He first Education Council for our A, Band C went to Television Recording at TVC courses. ETD will certainly be facing up CH1.d later became an Education to the challenge of the new and changing Engineer. Broadcast Technology and will continue He left the BBC in 1965 to read to produce broadcasting staff that for his doctorate at University College command respect the world over':

'Eng. In/. ' Summer 1980 - Page 7 We Deserve Reflected Glory-DE accorded in this country and overseas. been converted at all, and the lead we are kind of high quality sound reproduction And much of that respect is reflected on taking in in radio has that they cannot obtain from anywhere to everyone of us in BBC engineering. prompted at least one journalist to else. Wherever we work, we all contribute to suggest that the record industry needs The excellence of BBC engineers that engineering excellence and we to look to its laurels because the BBC has contributed considerably to the deserve the reflected glory." are yet again giving hi-fi enthusiasts the respect that BBC programmes are Bryce McCrirrick UK Beats World Rivals Speaking at the IEEE's Chicago Conference on Consumer Electronics on Wednesday 18th June, John Chambers, Head of Special Projects Section at Research Department, described how the British Teletext system can be extended through to broadcasting full-colour high- definition still-pictures as and when the cost of memory has fallen enough to let viewersafford the decoders of the future. Chambers described enhancements to the present teletext transmission U.K. Stand at Chicago. (Inset) Enhanced CEEFAX system including being able to underline words and change the colour of every pages and it would also receive pages decoder's memory. letter in a word. This shows that British which use the new characters and One other refinement described is display features not available in the a page-check word. A very short digital Teletext can handle 'parallel attributes' message enables the decoder to check just as well as any other proposed text earlier decoders'. broadcasting systems. Chambers also introduced some positively and automatically whether a He also described a way that allows very new ideas in teletext broadcasting. page has been correctly received. This teletext to specify codes for about 220 Foreseeing a decoder with one megabyte would have applications to business display characters as opposed to the of memory, he described how teletext computer systems and the like whr.re existing 96. Then a common core could broadcast full-colour still pictures. perhaps several hundred pictures are to alphabet of 200 characters, currently The same memory could accommodate be stored automatically. being discussed by the European around one thousand teletext pages and Most of the potential develop- Broadcasting Union, would be possible, a technique called 'Linked Pages' would ments of teletext rely on the reduction The common core alphabet would allow give the viewer instant access to these in cost of digital storage. At the Latin-alphabet based languages to be pages at the touch of one button on a moment the teletext system offers a used with a common decoder. keypad. Once the viewerhas chosen any proven way to start teletext broadcasting Languages could even be mixed within particular page the decoder would auto- as adoption in Australia, Austria, a page. Other alphabets could be matically me away a set of related pages , West Germany, Netherlanoo described using separate data lines to tell by obeying commands hidden in the and would suggest. Chamb. the decoder how to draw characters that transmission of the first page. When the foresees a hierarchy of developments are not stored in its character-generator. viewer was ready to read one of the that can be introduced stage by stage as Chambers says, 'These proposals related or 'linked' pages there need be the market allows. for enhancing British Teletext retain all no waiting time because the page would Chamber's ideas are published in the advantages of the fixed-format already be stored in another part of the BBC Research Report number 1980/4. Components To Lead Digital Future have a digital standard that will make it In April some 100 EBU engineers Technical Committee. Howard Jones of possible to do 'downstream' CSO as from 25 countries, met at the BBC in Research Department is Chairman of 2ffectively as it can be done at the RGB London. One of their main aims was to the VI-VID group. source. There was a suspicion that some discuss future digital television technical The demonstrations used a system fundamental limitation associated with standards. The initial recommendation known as '12:4:4', referring to the 4MHz sampling was being exposed and to the CCIR, is that the digital video 12MHz sampling for the luminance further work will be necessary. standard be based on coding the lumin- signal (756 samples per TV line) and Other demonstrations showed ance and colour-difference components 4MHz sampling for the colour digital mixing and recording from digital of the video signal separately rather difference components, B-Y and R-Y. 12:4:4 inputs were within the capabilities than the composite signal. Further The demonstrations showed that of present day signal processing and work will be needed on sampling rates the 12:4:4 standard preserved the recording technology. before the standard can be finalised. original RGB quality very well. The meeting in London demon- Operation with Colour Separation One significan t aspect to the strated one proposal of EBU specialist Ove,day (CSO or chroma-key) were less meeting was a visit by a party from the group VI-VID to the main EBU successful. Broadcasters could like to S.M.P.T.E.

Page 8 - 'Eng. In/. ' Summer 1980