November 14 th 1982 sees the 60 th anniversary of the BBC's first broadcast. Although there is only a psychological magic about round-number anniversaries, there is perhaps justification for a look back over the past decades and a look forward to those in store.
The essence of broadcasting is, of course, the programmes. But, as in any industry, production and distribution is founded on engineering; and the past 60 years have seen a very fruitful relationship between engineering and programme developments, each offering challenges and opportunities to the other.
The history of BBC engineering can fairly be called a success story. In case this sounds immodest, coming from a BBC pen, I would say that the ingredients of success were there from the beginning and that failure to exploit these would have been a surprising waste of opportunities. Let us examine what these initial ingredients were.
Broadcasting was one of the first major users of the brand new technology of electronics. It was a technology which clearly had great potential for development and it was therefore attractive to resourceful and inventive engineers.
Broadcasting in the UK was founded on public service ideals and with the philosophy of aiming for the highest achievable standards, both in programme and engineering terms. This philosophy meets with general public approval, so that engineers and others in broadcasting feel that their best efforts are appreciated and fulfill a worthwhile social need.
The product (that is the programmes) can be of such variety as to suit all tastes for much of the time and is therefore in continuing and increasing demand. Engineering developments contribute directly to more and better programmes, and hence receive general support.
The benefits of good engineering have always been recognized within the BBC and financial investment has been adequate to secure continuing expansion and improvement. The required a scale of investment, in terms of cost per head of the audience, is not very large and it has been possible, therefore, to direct engineering developments towards high quality rather than the lowest cost. So BBC engineering started healthily, has grown healthily and seems set for healthy maturity.
Wireless Before Broadcasting
Wireless communication originated in the 1880s with the experiments of Hughes and Hertz, based on the earlier theoretical studies of Clerk Maxwell. Before the close of the nineteenth century, Marconi had established himself in England and was doing imaginative work to increase the reliability and range of the new medium; he succeeded in transmitting signals across the Atlantic in 1901.
For this early work, spark transmitters were the norm and the detector usually employed was the coherer, in which metal filings were induced to 'cohere' under the influence of incoming radiation and hence provide a low-resistance current path for a bell or relay. Being an on-off device, the coherer could be used only for digital signals, such as Morse code.
In the early 1900s attention was turned to wireless transmission of telephony. For this a continuous carrier wave was required and the first systems employed modulated high-frequency alternators and electric arcs. Recognizable speech was transmitted by these means, but the quality must have fallen well short of todays standards.
Shortly before World War 1, the triode valve, developed from Lee de Forests Audion, began to be used for generation of continuous carrier waves. The relatively pure waveform produced, and the comparative ease of modulating such a source with speech signals, opened the way to wireless speech transmissions of reasonable quality. Receivers during this period employed crystal detectors, or Marconis magnetic detector, in which the changing magnetic state of an endless loop of soft-iron wire served to demodulate incoming signals. Wireless was, of course, very largely used as a means of communicating with ships at sea and the magnetic detector proved far more mechanically stable than the more sensitive crystal detectors, whose cats whiskers were easily jolted out of adjustment by the rolling and pitching of a ship.
The military necessities of the 1914-18 war gave a considerable boost to wireless development. Engineers fully appreciated the virtues of the valve and the French R valve in particular was an outstanding development in terms of performance and stability, together with the Marconi Q valve. The widespread use of valves in transmitters and receivers, and the development of tuned-circuit arrangements of reasonably good sensitivity, made usable wireless equipment available on a mass production basis.
Start of Broadcasting
After the war, a lot of military wireless equipment and components came on the general surplus market and was eagerly bought up by amateur enthusiasts keen to try the intriguing new technology for themselves. Many people built crystal or valve receivers, but of course there was not much of interest for them to receive. The regular time signals (in Morse) from the Eiffel Tower had been transmitted since 1909, and were a useful facility for checking that a receiver was actually working: but they were of limited entertainment value.
Realising that there was a gap to be filled, an enterprising Dutchman commenced in 1919 a regular schedule of Sunday evening transmissions of music and speech which became known as the 'Hague Concerts. These were much welcomed by listeners in the UK, as well as in Europe, and indeed were financed for a time by British listeners, following an appeal by Wireless World, and by contributions from the Daily Mail. The entertainment potential of broadcasting was appreciated also by UK industry: 1920 saw the Dame Nellie Melba recital from the Marconi transmitter at Chelmsford, followed in 1922 by the Marconi stations 2MT at Writtle, near Chelmsford, and 2LO in London. Also in 1922, two other industrial companies set up broadcasting facilities Metropolitan Vickers in Manchester and the Western Electric Company in Birmingham.
Marconis 2MT transmitter at Writtle in 1922.
Thus it came about by 1922 that a number of organizations had seen and acted on the potentialities of entertainment broadcasting, primarily as a necessary aid to establishing a market for receivers. Many of these were eager to jump on the band-wagon and the time had come for some co-ordination and regulation.
Formation of the BBC
To bring order out of threatening chaos, the Postmaster General, who had refused to license any more independent stations, told those manufacturers wishing to be involved to get together to form a single company for broadcasting. Agreement was reached at a meeting at the Institution of Electrical Engineers at Savoy Hill, London and the British Broadcasting Company was formed. Six large manufacturers combined in this venture, Marconis, Metrovick, Western Electric, GEC, BTH and the Radio Communication Company, with John Reith as the General Manager.
The new BBC took over existing studios and transmitters, hitherto operated by the individual manufacturers. Its first broadcast was from the 2LO station in London on 14 November, 1922, with 5IT in Birmingham and 2ZY in Manchester on the following day.
The BBC remained a commercial company until 1 January 1927 when it was reconstituted with a Royal charter as the British Broadcasting Corporation.
Apart from operating the existing studios and transmitters, the first task of the Engineering Department was to spread coverage over the country. By 1924 there were nine main stations and eleven relay stations. Public interest and demand was very buoyant, and in 1925 there were nearly a million licence payers and no doubt many unlicensed listeners.
Although the main engineering efforts after the start of broadcasting were directed to such basic necessities as providing acceptable quality from the studios and distributing programmes as widely as possible throughout the country, there was time too for more innovative work. In 1925, for example, transmitters in London and Daventry were paired for an experimental transmission of stereo sound from an operatic performance, although it was to be forty years before these efforts bore final fruit in the form of regular stereo programme transmissions.
Expansion of radio. At the beginning, the various stations in different parts of the country transmitted their own individual programmes from their own studios. This was indeed local radio, one more thing in broadcasting that is not as new as we may think today. It was not long before a 'simultaneous broadcast system of lines was established, enabling all transmitters to radiate a common programme as a network when required. Soon after this, a high-power, long-wave station, 5XX, was built at Daventry, giving coverage of much of the country and giving listeners a national alternative to the regional programmes from the existing stations.
Another important step forward was taken with the opening, in 1932, of the Empire Service, broadcasting to the world on short waves. One of the first broadcasts in this service was the Christmas message from King George V on 25th December 1932.
The higher-power main transmitters were obtained from commercial suppliers, but no manufacturer could offer low-power equipment for the relay stations. Accordingly, these were designed in the newly-formed Development Section of the BBC Engineering Department. Later, they designed high-power, 50 kW transmitters, again because none were available from commercial sources.
The first broadcasting engineers had to be resourceful men. Not only were they continually breaking fresh ground on the technical front, but those operating the transmitters and studios were often called upon to fulfill announcer duties and even to act as 'uncles in the children's programmes. What with this, and the fact that the first chief engineer Peter Eckersley had himself provided much of the entertainment on the original 2MT programmes, one wonders why it has since become necessary to have an army of producers, writers and performers to put the programmes across: perhaps they should have left it to the engineers!
The other important task for engineers in early days was to improve the quality of sound from the studios. Microphones needed much attention and a lot of cooperation between the BBC and industry was devoted to improvements over the original carbon granule types. One of the better new developments was the Magnetophone from the Marconi company. This gave a considerable improvement in quality, although requiring very skilled personal attention in that the voice coil was attached by pieces of cotton wool impregnated with Vaseline. If the studios became too warm, the Vaseline melted and more had to be applied: perhaps this was what gave rise to a skilled operator becoming known as 'dab hand.
Studio acoustic plays a vital part in determining transmitted sound quality. Virtually nothing was known of these techniques when broadcasting began, and much early research effort was devoted to the subject. Many of the fundamental principles were established at this time, and BBC Research Department maintains a strong and continuing effort in this field at the present day.
For the first eight years of the BBCs existence, all programmes were broadcast live. Although some programmes were recorded on disc by commercial recording companies for special purposes, programme production and scheduling suffered from the very severe handicap that no operational recording apparatus was available. Although the magnetic tape recording seems now to be the modern successor to disc, it was a magnetic system which was first used within the BBC. This was the Blattnerphone, using steel tape as a medium, which was introduced in 1930. It was five years later, in 1935, that disc recording was first employed, supplemented in 1936 by the Philips-Miller mechanical (not photographic) sound-on-film system.
From the early 1930s, then, all the fundamental ingredients for broadcasting were there: studio and outside broadcast origination equipment of acceptable quality; recording systems; and increasingly country-wide and world-wide transmitter networks. From then on, the story of radio up to the present day is one of improvement, expansion and sophistication. One should mention highlights such as the enormous improvements in audio quality in all parts of the chain, from studio acoustics to loudspeakers; the introduction of VHF and stereo; the expansion of programme networks at home and overseas and the start of local radio; the use of digital programme links between studio and transmitter; and the start of digital sound recording. All these things represent 'very much more and 'very much better, but all rest on the foundations completed by 1930.
The first BBC television transmissions of took place in 1926, when experimental broadcasts of pictures from Bairds 30-line apparatus were carried by the 2L0 transmitter. There were further tests in succeeding years and in 1932 the BBC set up a 30-line television studio in the newly built Broadcasting House.
A rather different form of 'television was experimentally transmitted in 1928. This was the Fultograph slow-scan, still picture system, wherein radio signals from a medium wave transmitter actuated a facsimile paper printer. Recognizable pictures could be reproduced at the rate of about one every five minutes, but the system created little public enthusiasm.
During the 1930's, Baird up-graded his system to 90, 120 and 180 lines. In 1938 the BBC set up a purpose-built television studio and transmitter at Alexandra Palace, including Baird equipment, now operating on 240 lines. Also installed at Alexandra Palace was 405-line equipment from the Marconi-EMI company. This was an entirely electronic system, as opposed to Bairds electro-mechanical devices, and side-by-side trials revealed it to be much superior. Accordingly, after a few weeks of alternate transmissions by the Baird and EMI systems, the former was abandoned and transmissions from January 1937 continued on the EMI system alone.
The engineers and the programme makers quickly learnt the potentialities and limitations of the equipment; and quickly built up a body of increasingly sophisticated production techniques. In May 1937 quite comprehensive outside broadcast coverage was given to the Coronation of King George VI, a very ambitious venture at that early stage in television history.
Testing for the 1937 Coronation television transmissions from Apsley Gate.
Expansion of television. During the 1939-45 war, the frequency requirements of radar had to override those of television, and the service was closed down for the duration. It opened again in June 1946, in time to cover the Victory Parade on 8 June: the BBC television service was the first in Europe to re-open after the war. In 1946 the television service had only the two studios at Alexandra Palace and two OB units. The one transmitter covered only the London and Home Counties area and there were little more than 20,000 viewers.
As had earlier been the case with radio, television suffered very much from the lack of any recording systems. Much research and development effort was applied to the problem and a workable system of recording television pictures on film was in use tentatively by the end of 1947, with an improved version being in regular service in 1949.
35 mm Moy-Cintel rapid-pull-down telecine equipment in 1958.
The scene was then set for the big expansion of television which the public wanted. Television transmitter coverage was extended to the major regional population centres and increasingly into more remote areas of the country. New studios were established, first at Lime Grove in West London, later in the purpose-built Television Centre and in numerous regional cities. Outside broadcast equipment and operations multiplied, taking events from anywhere in the country and eventually from overseas. Great improvements were made in the quality and sophistication of programme origination equipment, including of course the introduction of magnetic video tape recording which freed programme makers from so many shackles of location and time scheduling. Ever extending links, including satellites, gave comprehensive national and international programme distribution and exchange, with standards convertors of continually improving quality.
Particularly notable were the start of the competitive commercial television service in 1955; and the second BBC programme in 1964, coincident with the start of 625-line television in the UHF band. The introduction of colour on BBC2 in 1967, the first colour service in Europe, was perhaps the biggest single engineering change since television began.
Teletext, offering an entirely new information service riding on the back of the television signal, started in 1974 and heralded the first real public availability of the information technology which is so much in the news today.
Broadcast Engineering Today
So where are we now after 60 years of broadcast engineering? On the programme production front I would say that we have reached the point where engineering does not seriously limit the range and nature of programme making. In radio and television studios, and in outside broadcasts, producers have nearly all the technical facilities they need, with very satisfactory quality and reliability, to give their creative ideas full scope.
Programme making is now constrained more by limitation of resources. There may not be enough studios, OB units, tape recorders and the like to satisfy all programme demands, but this of course comes down to economics. In the end it is the consumer who has to pay for the equipment, plus of course the artists' fees and the non-engineering costs, and somewhere there are economic, social and political limits to the overall cost of broadcasting.
While programme-origination facilities may have reached a very acceptable state of development, the same cannot be said of programme distribution. Here there is still much engineering work to be done, even before we start to consider the new satellite and cable systems which the near future holds in store. The UHF television networks today cover 99% of the population of United Kingdom and VHF radio networks cover 97% (or 95% in stereo). MF/LF radio networks provide lower percentage coverages, dropping appreciably lower still after dark television and VHF percentage coverage in upper nineties may acceptable at first sight, but it must be remembered that every 1% of the population not covered represents half a million people.
It is a source of frustration and distress to transmitter network planning that the half million people unserved with television, for example, refuse to move together into one convenient mass. They are, of course, distributed throughout the country, often in very small communities, and it has so far taken about 600 television transmitters to achieve 99% coverage. Further relay stations are being provided for communities down to 500 people, and in the mid-l980s groups as small as 200 will be catered for. This television transmitter development programme is handled by the BBC and the IBA as a joint project and represents a major continuing effort over many years. Only eleven groups of four channels are available in the UHF broadcasting bands and very elaborate planning is needed to enable the hundreds of stations to be operated without mutual interference. BBC Research Department have built up a computer-based frequency-planning system, taking account of geographical and topographical features, which enables maximum use to be made of these scarce frequency resources.
In sound radio, the MF/LF bands are increasingly overcrowded and subject to foreign interference. The BBC is effecting marginal improvements here and there, but in general it is not possible to do anything very significant and it is to VHF radio that major development efforts are directed. Current work includes the addition of a vertically-polarized signal to the existing horizontally-polarized transmissions, offering considerable benefit to users of portable and car radios with vertical rod aerials. Another important project is the continuing spread of stereo transmission throughout the country, progress on this being determined primarily by availability of digital audio PCM links to the appropriate transmitters.
But the prime requirement for development of VHF radio is availability of more frequency channels in the VHF Band II. Without these it is not possible to provide the additional networks to avoid the current necessity for sharing of a VHF channel by Radio 1 and Radio 2, by Radio 4 and educational programmes, and to provide Radio 4 VHF coverage in the national regions of Scotland, Wales and Northern Ireland. Furthermore, we need additional frequencies to accommodate about 100 relay transmitters, which are needed to fill the gaps in existing VHF coverage.
The VHF Band II is, by international agreement, to be extended up to 108 MHz for broadcasting use, but the Home Office timetable for re-locating the emergency and mobile services using the upper part of the band at present is disappointingly slow. It appears that real progress on VHF coverage is going to have to wait until 1990 or thereabouts.
So our 60 years have brought us to a very satisfactory state of studio and OB origination quality and facilities, although improvements and refinements will, of course, continue; but availability of television and radio services to all the public is by no means complete and much work remains to be done to improve this.
The first priority of BBC engineering in 1922 was to extend coverage and, while enormous progress has been made, it remains a priority today.
It is fashionable nowadays to talk of 'the technological revolution. The term has become a cliche which all decent men now avoid, but it cannot be denied that it is in some senses a true one.
Certainly, there are technological developments now in progress which will profoundly change the broadcasting scene. There will not be dramatic technological revolution there never has been one but in the next few years we shall all become increasingly aware of major changes and new opportunities.
The first and the most publicly obvious area of development will be the provision of additional programme channels. In television, the start of the 4th channel (ITVs second programme) is upon us and this will complete the exploitation of terrestrial broadcasting in the UHF Bands IV and V. The obsolete 405-line television services in the VHFnBands I and III are in process of being closed down and it is possible, although not yet decided, for Band III to be re-engineered to provide a fifth 625-line television network, perhaps on a regional basis. No other VHF or UHF spectrum is allocated for television broadcasting, so that four television programme networks with the possibility of a fifth will be the long-term limit of terrestrial transmission. Provision of these additional channels represents 'more of the same' rather than any technological innovation.
On a different level (literally!) is the introduction of direct broadcasting by satellite (DBS). Satellite reception on a domestic basis has indeed been made feasible by recent technological advances, although these are refinements of techniques already used in the communications field rather than a current new development. With most other European countries, the UK has been allocated five DBS channels in the 12 GHz band and the first two of these will be made available for two new BBC programme services from 1986. The remaining three UK DBS channels will no doubt be allotted in future years. The year 1986 will therefore see six broadcasting television programme channels in the UK, with the possibility of the total rising to ten in future years.
The number of television programmes available could increase even further as the proposed wideband cable systems come into operation. In theory at least, a wideband cable system could carry thirty or forty television channels and to this can be added the choice of programmes available in the homes of people equipped with video-cassette or disc players. As one final tit-bit, it will be possible for some satellite receiver owners who are willing to spend a bit more money to receive programmes from foreign satellites in addition to those of the UK.
Improvement of the technical quality of vision and sound has been a continuing process since broadcasting began. But there are now more opportunities for particular advances stemming from the 'technical (r)evolution'.
Prototype dish for satellite television broadcasts.
Satellite broadcasting, for example, offers such advancement The effective video bandwidth which can be modulated onto a 27 MHz satellite channel is, at about 10 MHz, appreciably wider than the 5.5MHz offered by existing terrestrial transmissions; and this wider bandwidth can readily be exploited to remove some of the defects of the present PAL signals. Conventional PAL employs ingenious interleaving of the brightness (luminance) and the colour (chrominance) components of the signal, but exhibits some degree of mutual interference between luminance and chrominance, resulting in the flashes of false colour on finely detailed patterns (cross chrominance) and moving dot patterns on sharp edges (cross luminance). Both these cross effects are minimized by restricting the luminance bandwidth of the PAL signals in the receiver, but this results in limited picture definition and leaves some of the cross effects still apparent.
Extended Pal. Top picture shows part of Test-Card F as seen in the studio. Second frame is picture as normally seen with existing equipment-distortions in the frequency bars are evident. Third picture is picture transmitted by Extended Pal but received on conventional equipment. Final frame shows result of E. Pal transmissions and E. Pal decoder.
The wider satellite bandwidth will enable us to transmit luminance and chrominance signals separately, so that cross effects are eliminated without the need to restrict luminance bandwidth. The Research Department has evolved a system known as Extended PAL to achieve this, offering satellite pictures of full 5.5 MHz resolution with no cross colour or cross luminance distortions. With Extended PAL transmissions, existing receivers could still be used and would enjoy freedom from cross colour and cross luminance; while a new receiver, designed to exploit Extended PAL to the full and embodying a high-resolution cathode-ray tube display, would give the additional benefit of appreciably sharper pictures.
BBC satellite up-link terminal coupled to a standard radio-link van.
The IBA has also devised a system to exploit video satellite bandwidths. Known as Multiplexed Analogue Components (MAC), the IBA system also offers freedom from cross colour and cross luminance, although in the form proposed there would be no significant improvement in picture definition.
Both Extended PAL and MAC provide separate transmission and reception of luminance and chrominance components. Given this, modern digital storage and signal-processing techniques offer the possibility of standards conversion within the receiver at a cost which would be acceptable in a domestic product. The implication of this is that picture signals, although still transmitted in 625 line 50 field/s form, could be converted in the receiver and displayed on a higher standard with, say, 1250 lines or 100 field/s or both. Although there would be no more information transmitted, a display with much less visible line structure and free from flicker could be subjectively far more pleasing. Considerable research effort has gone into these possibilities, with the hope that a large, bright, high resolution display device will appear in due course to do justice to such advances.
The longer-term goal is, of course, true high-definition television (HDTV) whose picture would be actually generated and transmitted on high line and field rates and would thus genuinely carry more information. The difficulty is that real HDTV would require a bandwidth of some 30 MHz and is thus beyond the capacity of currently-planned satellite channels in the 12 GHz band, unless it could be accepted that two or three 12 GHz channels could be employed for a single HDTV signal: but this seems an uneconomically lavish use of the available spectrum.
Progress towards broadcast HDTV must be either in considerable advances in bandwidth-comparison techniques, or in the use of a higher-frequency (say 40 GHz) satellite broadcasting band where more spectrum space could be available. But such high frequencies are very susceptible to absorption by rain or snow storms, so the viability of this approach must be in doubt. The ingenuity of BBC engineers, and others, will certainly be focused on these problems in the years to come. Not only are there intriguing possibilities for improvements in picture quality, but sound signals also can be expected to show dramatic advances. A satellite broadcasting channel will accommodate, in addition to wider-bandwidth picture signals, a number of high-quality digital sound channels. BBC proposals, for which it is hoped soon to receive international agreement, envisage six such sound signals with each of the two satellite channels, of which two would form a pair for stereo sound accompanying the television picture, with the remainder affording a vehicle for high quality stereo radio programmes.
The advent of the BBC satellite broadcasting channels in 1986, therefore, will see the first direct transmission of digital sound and the first opportunity for broadcast stereo television sound in the UK.
The BBC, some years ago, conducted experiments in the terrestrial transmission of digital sound signals. These were not very successful due to digit corruption by multipath (reflected signal) effects and it is difficult to see how this problem could be overcome. Satellite signals are not, of course, subject to multipath distortion.
BBC investigations into the possibilities for stereophonic sound on terrestrially-transmitted television are accordingly based at present on analogue methods. On-air experiments with a dual sub-carrier analogue system are currently in hand, the critical factor to be assessed being the absence of interference to existing, monophonic, television receivers. The addition of stereo sound to terrestrial television will surely come, but is likely to be some years in development. Even when a satisfactory transmission system is agreed, a long and expensive programme of work will be needed to provide a stereo sound distribution system from the studio centres to the country-wide transmitter network.
Other Forms of Distribution
Distribution by wideband cable (optical fibre or co-axial) and by video disc could be free from the bandwidth restrictions which limit the capabilities of terrestrial and, to a lesser extent, satellite broadcasting. The extent and the time scale of implementation of these new media cannot at present be forecast with any certainty, but the potential is there for exploitation of many of the ideas which are being generated by engineers with broadcast applications in mind.
Development of cable systems, in particular, leads some people to forecast the eventual demise of broadcasting. But from an engineering standpoint, cable is simply another means of programme distribution and there is no fundamental reason why broadcasting (and the BBC in particular) should depend for its existence on distribution by radiated signals. BBC engineering will adapt in the future, as in the past, to whatever technological advances are appropriate to the time and will no doubt be ready to exploit the potentialities of cable or any other distribution methods. This is not to say that the BBC is now considering setting up or operating a cable system on its own account, any more than it plans to build and launch its own satellite, but it can be expected to continue to. play a significant role in the technological development of distribution systems of the future.
Extension and refinement of digital techniques will surely be the dominant theme in the development of studio origination equipment. BBC engineering research and development has been in the forefront of many advances in this area and will certainly continue to be so, both nationally in collaboration with British Industry and in the international sphere, where co-operation and standardization are so important.
The main advantages of digital signals land equipment are reliability and resistance to distortion. These virtues are of great importance to a large broadcasting organization, where breakdowns or signal impairment are expensive hindrances to the tightly-knit flow of programme production: but, like many virtues, they are perhaps a little unglamorous. More obviously exciting are the opportunities offered, not so much by digitization as such, but rather by the ease and economy with which digital signals can be stored and manipulated. Once a picture signal can be held in store and made available for manipulation, all sorts of possibilities present themselves in the way of special effects, graphics, standards conversion, noise reduction, removal of blemishes and programme editing. Digital storage is also fundamental to the development of information systems such as teletext and the radio-data system for identification of radio programme signals.
In the early 1920s, BBC engineering seized on the new technology of electronics and carried it forward in the broadcasting field with enthusiasm and innovation. In the early 1980s, we are once again in the fairly early stages of what is virtually a new technology, that of microelectronics and digital processing. Once again, a broad vista of new opportunities opens up before us and the next 60 years of BBC engineering promises to be as exciting as the first.
* pat Leggatt - Head of Engineering Information.