Progress in engineering 

10 April 2023 tbs.pm/76973

 

Cover of Television & Radio 1979

From ‘Television & Radio 1979’, published by the Independent Broadcasting Authority in December 1978

A major development in the IBA transmitter network has been the completion and bringing into operational service of the first of four new Regional Operations Centres at Croydon, London. From a single control console, an IBA engineer can supervise the television transmitters serving almost 20-million viewers in an area that extends from The Wash to Dorset and reaches down as far as the Channel Islands.

More than four years of planning, designing and development work have gone into this ‘ROC’ which replaces five of the original Colour Control Centres set up in 1969 when ITV’s colour service began.

Many entirely novel forms of transmitter ‘status’ and information retrieval displays keep the controller in touch with what is happening throughout his large area. Receiving aerials mounted high on the Croydon tower bring in high-quality signals from transmitters 50-70 miles away to allow quality monitoring of the programmes transmitted in the various regions.

Within the area served are eleven uhf high-power ‘main’ transmitting stations, five ‘main’ vhf stations for the now little-used 405-line black-and-white service, and sixteen of the larger uhf relay stations. All of these unattended stations, in addition to automatic operation, can be remotely controlled and the ‘status’ of their equipment monitored. In addition there are many small local stations for which Croydon now acts as the Operations Centre.

ORACLE teletext

It was on 9th April 1973 that 1BA engineers demonstrated to distinguished visitors a brand new system for broadcasting the written word – ORACLE. This was the first such demonstration, anywhere in the world, of the system that has since been further developed and is now often known as ‘teletext’. Since 1975 the ORACLE service has been the responsibility of the ITV programme companies with editorial units at London Weekend Television and ITN and technical facilities also at Thames Television.

 

ORACLE front page

One of the index ‘pages’ displayed in ITV’s ORACLE Teletext broadcasting service which has been developed by IBA and ITCA engineers. The line of information at the top of the screen includes the selected page number, date and time to the nearest second.

 

The teething problems of this fascinating and rapid service of continuous news and information are, hopefully, now over. Any ITV viewer in any ITV region can, between 9.30 a.m. and 10.30 p.m., select up to 200-300 ‘pages’ of crisply presented news – international news, home news, financial news, sports news, weather forecasts – and information: what’s on in television, radio, theatres etc. Later on it is expected that local news will be inserted into the service by editorial units located within the regions. In effect, teletext turns a television receiver into a visual display unit linked with a computer, providing the viewer with a useful service at no cost.

Space experiments

A man stands beside a large satellite dish

The compact satellite Earth station in the grounds of the IBA’s engineering centre at Crawley Court, near Winchester.

Watching World Cup football from Argentina or news stories from Washington DC or Southern Africa, we tend to forget the days when it was an adventure to see even hazy television pictures from across the Channel. It was the space satellites – Telstar, Early Bird and the Intelsat system – that really opened the television windows on the world.

Now it is almost routine, though still fearsomely expensive, to bring in pictures via Intelsat – but is this to be the limit of the contribution of satellite technology to our screens? Many engineers believe that one day

it will do much more. Quite soon they see the Eurovision network, linking the broadcasters in Europe and North Africa, carried on a dedicated satellite, with the possibility of injecting pictures directly into the network from compact and even mobile earth stations, giving a further impetus to ‘live’ electronic news gathering. Beyond that they believe that one day viewers will receive their pictures and sound directly from broadcasting satellites stationed thousands of miles away 22,300 miles above the Equator.

This will not happen tomorrow, although the technical feasibility is virtually already established. In Europe plans are well advanced for experiments and further studies into the advantages (and disadvantages) of such a radical change. It would mean for instance that viewers would need a new type of electronic aerial unit working at frequencies more than a dozen times as high as any now in use for television broadcasting. It would have to be carefully installed – and nobody is sure yet whether a suitable receiving system could be mass produced at sufficiently low cost. But it would mean that virtually 99.9 per cent coverage of the country could be achieved from just one satellite transmitter. But then what about regional television?

 

Posterised image of a huge satellite dish

Listening to the stars. Will the giant radiotelescopes of Jodrell Bank pave the way for satellite broadcasting to small dish aerials less than a meter in diameter?

 

There are thus many problems – technical, financial, administrative – still to be solved. Meanwhile IBA engineers are studying the technical problems. A special compact earth station is being used at Crawley Court to study the way in which, for example, heavy rain or ice particles might affect reception (not very much unless the weather was to be really exceptional!). This knowledge is essential if the Eurovision network is to transfer to satellite distribution in the early 1980s.

The ‘all-digital’ studio

For the engineer, present-day television is a mixture of the sad and the stimulating. Sad because much of the system is so far from being ‘state-of-the-art’. Pictures are transmitted essentially in the same way as the pioneers of the 1930s. Stimulating because the engineer knows how real improvements could be made and what still needs to be developed in order to do this. Of course there is more to changing a large existing system than technological development.

Would viewers want a better system if they had to buy new and possibly more expensive receivers? Would industry be willing to make the necessary investment? Would the broadcasters welcome new technology if it might lead to industrial problems?

The impact of microcircuits is already considerable but the broadcasters are only on the threshold of bringing computer technology into the studios and transmitting stations. Equipment that will be smaller, lighter, more sensitive, consume less power and above all have the greater ruggedness made possible by computer-like digital signals: these are all considerations for the near future.

 

A man sits at a very large telecine machine

Highly developed equipment, like this flying spot telecine machine installed in ITV’s Manchester studios, ensures that programme material shot on film can be converted into top quality television pictures. granada

 

IBA and ITV engineers have pioneered digital systems with the high-speed computer called DICE, that instantly converts American pictures into European ones and vice versa. More recently I BA has been working on the basic elements for an ‘all-digital’ studio, including the key requirement: an all-digital recording machine that uses only as much tape as the existing ‘analogue’ machines. Engineers from many parts of the world have beaten a path to Crawley Court to see the results. Still experimental, still more work needed – but clearly in advance of any comparable work announced anywhere else in the world.

The ‘silicon revolution’ of microcircuits is here to stay; television research engineers have powerful new technologies at their disposal. But this does not mean that the results will arrive dramatically on our screens overnight. It takes time: often advances come gradually and so pass almost unnoticed. But to the engineers each advance brings nearer the day when all our pictures are perfect and television can go anywhere, see anything and at last we can begin to ask ‘how good is good enough?’.

Frequency allocations

For the immediate future there are still many practical questions awaiting solution. During 1979 an important conference of the International Telecommunications Union is to be held in Geneva, Switzerland concerned with the allocation of radio frequencies for all the many services that depend on them, not only in Europe but throughout the world: radio and television broadcasting, of course, but also radio communications of all types and the complex radionavigation and radar aids on which aircraft and ships and defence depend.

 

A man sits in front of two monitors displaying computer graphics

By lightly touching a proximity switch an engineer at the new IBA Regional Operations Centre at Croydon can call up clear visual displays on a television screen of the equipment at a remote unattended station, complete with indication of any fault and even its likely location.

 

It is possible that more frequencies will be provided to allow an important extension in Europe of Band II (vhf/fm sound radio) and so help to make possible a rapid extension of local radio. On the other hand, the Band I and III vhf television bands are likely to be under pressure from users of mobile radio communications. This could mean that when the 405-line television services close in a few years time, these frequencies may be lost altogether to broadcasting in the United Kingdom. The Geneva meetings will help set the pattern of broadcasting for years to come – and it will be incredibly difficult to arrive at a table of frequency allocations that will satisfy everyone. The radio spectrum is universally recognised as a vitally important but limited natural resource.

 

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