New television standards: effect on British television 

19 February 2021 tbs.pm/72148

A Discussion on this subject was held on Thursday, October 22, 1959, the chair being taken by Mr. C. A. Marshall (Member of Council). The opening remarks by Mr. D. C. Birkinshaw (B.B.C. Television) are given below.

 

 

Journal of the Television Society cover

From the Journal of the Television Society, issue 4, volume 9, October-December 1959

This is a particularly appropriate time for this Society to stage a discussion upon new television standards and their effect on British television. The matter has been in the minds of us all for many years — indeed, from the time immediately after the war when it was debatable whether we should resume on 405-lines or wait and start on a higher standard. However, with Europe largely on 625-lines, and with an inevitable trend to U.H.F. broadcasting in sight, it is more than ever important that we should take a look at our own system and standards and the Television Advisory Committee — a body appointed for the purpose — is doing so, aided by its Technical Sub-Committee. It has not yet made a recommendation to the Postmaster-General and, indeed, this could hardly be expected in view of the magnitude of the subject and for various political reasons which are generally known.

Tonight I am speaking not as the Superintendent Engineer of Television of the B.B.C. but as a Fellow of this Society trying to suggest what are the problems confronting all of those who, in this country, have the responsibility for originating and transmitting television.

The brief is quite a formidable one because, before one can do this, one must know how it would be proposed to put the plan into effect and at present we do not know this, or even if there is to be any action at all. The final decision will be compounded not only of engineering but from political, commercial, national and international ingredients, and is a long way off yet. Tonight, therefore, we must resort to some preliminary guesswork.

It seems prudent to start from the standpoint that all non-industrial television exists because the public is prepared to pay to be entertained at home. At present that public is buying receivers in quantities which suggest that, for the time being at any rate, it is satisfied programmatically and technically with what it is getting.

 

Map of Europe

European and neighbouring areas line standards of the 1950s for the First Television Service in each area. Political borders are deliberately vague.

Key:
████ 405 lines, 5 Mhz channels
████ 625 lines, 7 Mhz channels
████ 819 lines, 13.15 Mhz channels
████ 625 lines, 8 Mhz channels
████ 525 lines, 6 Mhz channels
████ 625 lines and 819 lines, 7 Mhz channels
████ 819 lines, 7 Mhz channels
████ No television service or no data

 

This, of course, may not and I think will not always be the case, but we must assume that in launching a new standard we must ask ourselves the question “What are the conditions under which the public will support a new standard?” To what extent is this situation comparable with Sound Broadcasting where there has been an inducement to accept the new standard of frequency modulation on V.H.F. because the 150-1500 kc/s band (the Band I of Sound Broadcasting) has become so full of interference? To what extent also is the situation comparable with the recorded programme field where the many nuisances attendant upon the playing of 78 r.p.m. discs, such as scratch, short playing time and quality of reproduction, produced conditions favourable to the launching of long-playing records?

It is doubtful whether at present one could say to the lay public: “Look, your television picture could be better than it is; we propose to launch a new system, and if you will be kind enough to buy a new receiver, which is likely to cost you more than your present one, we can launch the system with confidence.” The public would reply that the system is all right as it is, why not leave it alone?

 

Courtesy of digitalmetadata

 

Extra Programmes

It follows, therefore, that if we are to launch a new standard, there must be some other inducement to the public to take it up, and that inducement is presumably an extra programme. Some say that even this would not be enough, and that there would have to be two extra programmes. Others still, say that new programmes are not enough, and that it, or they, would have to be launched on the new standard in colour.

Having considered the possible views of the man who ultimately pays the bill, the Broadcasting Authority must now consider those who are going to make the sets, and with this of course is bound up the means by which the new standard is transmitted. I suppose we may take it that if a new standard were launched, it would be on 625-lines.

In saying this I am of course guessing, because no decision has yet been taken about the specification of any new standard. I am simply assuming that if we were to change, we would be likely to come into line with Europe.

This new standard would require greater video bandwidth than at present, and this may well be 5 Mc/s. This bandwidth in turn would require a greater frequency separation between stations. These two factors are not the same, the station separation being greater than the video bandwidth. You can decide that you want a certain video bandwidth which may be 𝑥 Mc/s, and you can then decide what additional bandwidth it would be prudent to allow in order to accommodate the needs of vestigial side band transmission and the sound. Allowing also certain guard bands, one then has the required separation of 𝑦 Mc/s, 𝑦 being of course greater than 𝑥. In addition the vision carriers should be synchronized so that with the aid of offset, or precision offset, interference may be cut to a minimum.

 

BBC1 405 lines test card D

 

Many authorities in Europe use a 7 Mc/s station frequency separation, but a proposal that all the countries in Europe should use 8 Mc/s was made at the Moscow Conference in May 1958, and a tentative agreement was reached at the Los Angeles Conference in April 1959.

The total ether space for television broadcasting in the U.H.F. bands, (Bands IV and V) is not quite certain. Neither has the number of channels required to distribute one television programme over the United Kingdom in Bands IV and V been accurately determined.

However, certain studies have been made, and it does seem that, on a basis of a station separation of 8 Mc/s, there will be enough ether space to radiate three programmes. Moreover, each programme would need 50 or 60 transmitters of varying power for a largely complete coverage.

If, therefore, the inducement to the public to support the new standard were to take the form of one new programme, the authority responsible would need at least 50 transmitters. If two programmes, then at least 100 transmitters, and if a third programme were to find its way into Bands IV and V, as might be the case if we abandoned Band I, then the authority would need at least 150 new transmitters. These would vary in effective radiated power between 1 megawatt and 1 kilowatt, and the cost of such an array of transmitters, for one programme, might be about £10 million [£250m today, allowing for inflation], or for three programmes £20 million [£500m], at current prices. These are large figures for a broadcasting authority, and the manner of finding the money would form a major problem in itself.

 

 

Transmitter Power

These transmitter powers raise some interesting problems. In Bands IV and V I have given 1,000 kW E.R.P. as being desirable for the higher powered stations, but it might be that this would not be enough — 2,000 kW or more might be required. On these frequencies, one can get an aerial gain of 20 with an economic structure so that for an E.R.P. of 2,000 kW the transmitter output would be 100 kW. Using two transmitters in parallel, the output of each transmitter would be 50 kW. There is, however, no such thing as a 50 kW klystron, and it would be most beneficial to the transmitting authority if one could be developed.

It is interesting to compare these powers with those prevalent on Band III where a high-power station will have an E.R.P. of 200 kW, which is very much less than that required in Bands IV and V. On the other hand, the aerial gain which can be realized in an economic structure is also less at 10, so that the transmitter output power has to be 20 kW. This can be provided by two 10 kW transmitters in parallel.

 

 

These transmitters would require a new network to connect them to the programme distribution centre. This network would consist of cables and radio links with a bandwidth of, say, 5 Mc/s per programme. This might cost several million pounds more.

Since the programme to be provided by this network will be an additional one, the question of whether existing cameras and other originating equipment can be adapted to work on 625-lines does not arise, since the broadcasting authority will have to set up a new originating system anyhow. The nature of this system will depend upon the proposed content of the new programme, and it may not be constituted in the same way as the existing originating system. By this I mean that it might contain a greater or lesser proportion of studio, telecine and O.B. equipment. However, I shall need to return later to this question of convertability of existing originating equipment.

 

Courtesy of Vintage 405 line Televison

 

Receivers

We must now concern ourselves with the type of receivers. The easiest course for the broadcasting authority would be if the manufacturers could make receivers which could be switched between the radio frequencies and between the standards. Such receivers are in use in Europe to receive 625- or 819-lines and even positive or negative modulation. Moreover, a recent paper by C. J. Hall entitled “The Design of Dual-Standard Television Receivers for the French and CCIR Television Systems” concludes that the realization of dual-standard receivers does not present excessive difficulties, and that they need be neither unduly expensive nor complex as compared with normal television receivers.

In these circumstances, the broadcasting authority would set up the necessary new transmission system on 625-lines in Bands IV and V from London outwards, as happened in the case of the two existing systems.

 

 

The new service would be terribly uneconomic at first, but one would hope that either out of interest in the additional programme or programmes, or because of obsolescence of the existing Bands I and III receivers, the public would gradually buy the new receivers.

This state of affairs would go on for many years, and I do not know how much further into the future we are expected to carry our speculations here tonight.

One can imagine one or both of the existing Bands I and III services transferring to Bands IV and V either permanently or being gradually rearranged with the aid, both temporary and permanent, of channels in Bands IV and V, so as to enable us to distribute 625-line television on 8 Mc/s channels in Bands I and III. These Bands would jointly provide eight 8-Mc/s channels. Eight channels are more than enough to distribute one programme with almost complete coverage, but not sufficient to distribute two programmes at more than 85% coverage. So Bands I, III, IV and V, using 8 Mc/s channels could distribute four programmes well, or three well and two imperfectly.

 

 

But what if the receiver industry says that it cannot make receivers switchable between standards, and there is a body of opinion to that effect? This would provide a very serious problem for the broadcasting authority, which we must now examine.

Although the new receivers could only be constructed to work on 625-lines, the public would expect them to display, in addition to the new programme in Bands IV and V, the existing two programmes now originated on 405-lines. These would have to be originated therefore on 625-lines, and the broadcasting authority would be committed to the full programme of at least 150 transmitters, together with an appropriate distribution network. Since Bands IV and V will only accommodate three programmes, only one new programme could be launched as an inducement for the viewer to buy the new receivers and, as these would cost more in any case than a 405-line Bands I and III receiver, the progress under this plan would be slow.

For the broadcasting authority this would be a formidable and expensive task, relieved only by the fact that very little of the programme originating equipment now used for the existing programmes would need to be renewed. Existing television cameras have been designed for 625-lines and would only need a certain amount of modification. The same situation obtains in the telecine field, where the modern types of equipment, both continuous motion or vidicon projector, can readily be converted to work on 625-lines. Moreover, it is not impossible to adapt the older types of continuous motion equipment, should it be desired to retain these in service. Similar considerations apply to telerecording equipment.

However, the broadcasting authority has a further responsibility.

It will of course be necessary for several years to maintain the radiation of the present two programmes at the 405-line standard on Bands I and III, for the benefit of the millions of owners of existing receivers, and this despite the fact that the programmes would then be originated on 625-lines. The broadcasting authority would be saddled with the running costs of the existing networks and transmitters and, in addition, these programmes, in their 625-line form, would have to be applied to standard changers yielding 405-lines for application to these networks.

The difficulty is that the receiver with both standards and waveband switching is bound to cost more than one with just waveband switching. However, the situation presented to the broadcasting authority in the absence of standards-switchable receivers is, I think, beyond all reason, and in my view we must have the switchable receivers. It will be interesting to hear Mr. Wethey on this aspect of the matter.

 

Courtesy of ITV News

 

Introduction of Colour

In the foregoing it has been assumed that the new standard would be 625-line black and white, but it was suggested earlier in this paper that it might be important to introduce colour, by way of encouraging the audience to support the new standard. Apart from that, it might well be that by the time we come to set up a new standard, colour television would be thought by all concerned to be sufficiently satisfactory and economic to be worth launching.

Assuming then that the many problems still unsolved in colour television engineering have been sufficiently surmounted as to permit a start, it may be argued that no authority would dream of attempting to transmit the whole of its programmes in colour. Only those suitable would be so treated.

From this it follows that a certain proportion of the originating equipment would have to be built for 625-line colour and this would still further increase the financial burden on the broadcasting authority.

 

 

In addition, on the studio side, there would have to be a considerable increase in lighting power. Modern black and white cameras require a lighting power of 30W per square foot of floor area, while colour cameras may require as much as 150W per square foot. The implications would depend upon how far the broadcasting authority had foreseen an eventual change to colour, and therefore appropriately equipped its more modern premises. Clearly, if this had not been done then it is likely that a proportion of its studios would require a completely new lighting installation at heavy cost.

As regards running costs, such a studio would not necessarily consume five times the energy of a previous installation, because it is likely that there would be economy in production costs, such as lighting the minimum possible area at any one time.

 

 

Conclusion

I think I have said enough to indicate that the introduction of a new standard would be no easy matter for the transmitting authority. It would involve heavy capital expenditure and a major piece of planning to avoid dislocating the service to the public. No responsible broadcasting authority should ever do this. In this case, any trouble caused to the public would obviously have bad effects on our ability to sell the new standard.

I do not, however, want to appear pessimistic, or to suggest that the introduction of a new standard is so difficult that it can never be done. Although the purpose of our meeting tonight is to discuss what would happen if we endeavoured to introduce a new standard, and not the alternative subject “should we introduce a new standard”, I would like to spend a final minute or so on this latter aspect.

We have, on paper, the lowest standard in the world. We have it because we were the pioneers, and we are still hanging on to our first model. It is a very good model indeed, and if it really is satisfactory and, further, if it is going to be lastingly satisfactory, then we do not need to face the difficulties which I have outlined. Indeed, some of my technical colleagues say that at the present time it is impossible to devise a television system on any standard which will actually put on to the viewers’ screens a picture carrying more detail than the present system. They say that the only real effect of increasing the number of lines is to decrease the visibility of the line structure. It would be sheer economic folly to set up a higher line standard for the primary purpose of decreasing the line structure; that can be achieved by far simpler means. The true benefit of a higher line standard would be the display of more detail in the same size picture and a more satisfactory display of the larger pictures which will surely come.

I feel, however, that those who think in this way must surely have their attention too much on current technology. In the history of Applied Science one observes that apparatus and equipment for fulfilling a given purpose are constantly getting better over the years and, if it is not possible to make apparatus which justifies a higher standard now, then surely it will be in a few years’ time. The standards fixer should have his eyes on the distant horizon. I would say, therefore, that improvements in technology will enable us to utilize the higher standard; by the time that happens it will be important, in the interests of prestige, to get on to that standard. By that time I would suggest that the finances of the television services will have been set on a basis which would permit of the planning and execution of even the large scale operation which I have described tonight.

 

A COLOUR TEST TRANSMISSION - BBCtv

 

A Dick Branch presentation

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1 response to this article

Chad Henshaw 19 February 2021 at 12:24 pm

Oddly still relevant today. HD benefitted from having the digital switchover more or less at the same time so upselling a little to HD was no hard task. UHD/4K doesn’t really have that and hasn’t gotten far.

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