What 1935 May Bring

Radio Record, Volume VIII, Issue 26, 4 January 1935, Page 14

What 1935 May Bring

Practical Commercial: Television Transmission Of Moving Pictures Expected Within 12 Months

OBODY can afford to neglect radio at the present time, no matter how slight may be his interest in it as a form of home .entertainment. We have come to a great turning point in radio technical matters, and very soon the or ‘dinary man in the street may be made to realise that what the scientists are planning for the forthcoming year will have a great effect, not only on his enterbut on the more vital aspect of his existence. Seated in the comfort of his local picture theatre, — a man may occasionally ponder on the progress of television and wonder how long it will be before, radio brings living pictures into the home. -He may just occasionally feel that it wouldn’t be a bad plan if he could stay at home by his own fireside and see the entertainment and the events of the world flashed on. his own television screen. On wet nights the necessity for going even round the corner may make him wish that scientists would hurry the progress of television. The technical deficiencies of his present radio receiver may sometimes makes him feel that we are still a long way off from finality in aural broadcasting, quite from any development that may be made in the broadcasting of moving pictures. The man in the street must have a vital interest in the progress of radio for the forthcoming year if he gives any thought at all to his own comforts. The greater entertainment value of broadcasting ia the home, when television supplements the at present incomplete form of transmission, will result in a revolution of the whole entertainment industry. The immense chains of picture theatres all over the country obviously, could not be shut up without having serious repercussions in many other industries, and some rearrangement of television reception would be necessary to ensure that, although millions of people all over the country could ‘be assured: of the best entertainment and news services in their own homes, there would still be sufficient inducement to go to outside sources for new forms of entertainment, doubtless also resulting from broadcasting and television. Any radio listener is justified in asking the broadcasting authorities how far we are from the time when a revolution of this kind may take place. Already we have had a.taste of the chaos which can.result from rapid radio development without sufficient forethought. Even the local broadcasting stations do not always come in free from interference, and on the best sets to-day it is sometimes impossible to get a very large number of foreign stations without others constantly. ~ jamming and heterodyning, so that there is no real pleasure in ‘distant station listening. In Europe at least this ether chaos has come about because nations, to justify national pride, have been in too much of a hurry to put new broadcasting stations on the air. There is, after all, a very definite limit to the wavelength band which can be used for ordinary broadcasting without calling for very special apparatus to receive the programmes. The wavelength bands which to-day we know as the medium and long-wave are those which can be received on a comparatively simple

type of apparatus. It is by no means so simple to receive broadcast programmes if they are transmitted on ‘short and ultra-short waves, and yet there are so many stations jammed in the medium and long-wave bands that soon we must of ‘necessity have recourse to the short and ultra-short waves in order to find positions in the ether for all the stations transmitting programmes, There is a kind of ether policeman controlling the erection and broadcasting power of wireless stations all over Europe. This is the International Broadcasting _ Union, which by bringing pressure to bear indirectly through the Governments of the various countries endeavours to keep the radio peace and prevent t¢ too much station jamming. The:result is that ordinary receivefs are not selective enough. There is now no novelty in ordinary radio sets and people are constantly complaining that’ unless sets are made more selective so as to receive a large number of programmes free from interference, the pleasure of radio reception will’ soon wear’ off. . This development must always take place when the novelty of a new invention begins to wear off. The stage has been reached when, in the motoring world, cars are regarded as a convenience rather that a novelty. Cars are sow used to- day for business pur-, poses and time-savers, and only very occasionally as a direct source’ of pleasure. Even people who motor through the countryside and to the coast frequently do so only because that form of ‘transport is more conveni-. ent and comfortable than others. The same stage has now been reached with radio broadcasting, and it is the entertainment provided rather than the wonder of the method that appeals. If the entertainment valte is seriously reduced by interférence broadcasting as a whole begins to lose its value. There is already so much jamming on the ether with broadcasting stations which are transmitting only sound that I think you will realise the problem we shal! be up against when television is on the air as a new form of entertainment provider. . When television is on the air.each programme distribution centre will need two entitely different wavelengths, one for television and the other for sound broadcasting. At the moment, if ordinary radio trans-_ mission methods are not revolutionised, the only way out seems to be by the use of short waves. Then aural broadcasting will continue more or less on the present wavelengths and the short waves will be used for the transmission of pictures. This .will mean a big development during the forthcoming year, for although short wave reception is becoming increasingly popular it can at the moment bear no comparison to ordinary broadcast reception on the medium and long wave. Special apparatus is necessary and at the moment rather more skill is needed to operate a shortwave receiver than to control a medium or long wave outfit. Certainly ‘during the next ‘twelve months we shall look forward to big changes in receiver technique. The

By

PROFESSOR |

A. M.

LOW

In The "Listener In" (Melbourne) Professor Low is a very famous scientist, author of "Wireless Possibilities," "Tendencies of Modern Science," "The Wonder Book of Inventions," etc. ge fg a a ae ~"

time has come when ‘every successful receiver must be taken to operate from the electric light. rains, and although this can be very easily done on medium and ~ long wave receivers it is by no means so easy to operate a short wave outfit from such power supplies. All the little noises, crackles and interference which are introduced into the receiver by the electric light mains (and which pass almost unnoticed by ordinary broadcasting _ Set reception) are magnified enormously in a short wave receiver. When short wave reception is confined only to aural broadcasting and where, as at,the moment, it has little entertainment value, this electric light mains trouble is not serious. When, however, we have to

rely on short and ultra-short waves for our main broadcasting entertainment and when in addition television is introduced, | then this interference. will be serious. A slight hiss or rustle in the background of an . ordinary broadcast trouble is. seldom noticed even with the high quality receivers of to-day, but in a television outfit any ee,

SUEAE AMCELELOCHCE 15 UMUCUAtCly OVVIOUS Ol tle tele vision screen. and is made manifest in the form of speckled dots and wavy lines over the image. Detailed improvements in components are bound to be made for we are a long way from finality in the design of tuning systems, coils, detection systems and even in power amplification. .We must not decry the efforts of the power amplification engineers who have done such good work during the past five years in developing ‘large amplifiers for radio and sound film systems. The talkie film engineers indeed are to be ‘congratulated on several improvements they have made, and for the introduction of new forms of low frequency couplings, and of loudspeaker systerns. Many of these developments can be applied to domestic receivers, but, of course, the ordinary type of loudspeaker as we know it to-day is far from perfect. I can predict with confidence that before scientists are really satisfied with sound reproduction over a sufficiently wide frequency range, an entirely new form of loudspeaker will be introduced in which some means of transforming electric vibrations into sound waves will be incorporated. At present this transfomation is made by. means of a vibrating diaphragm, the moving part of the diaphragm being operated either by a magnetic or an elec-tro-static system. Electrostatic loudspeakers are becoming more and more prominent. This afterall is only a reversal of the idea of the condenser microphone as used by broadcasting engineers at the transmitting end. I feel, however, that all these systems have mechanical limitations which must be overcome before we can truly be satisfied with the last link in the chain of an aural broadcasting system. When details like these have been attended to, and we are quite satisfied that our radio link is satisfactory, then other television problems witl not seem so dfficult. We may now be only a few months away from | really successful film television. It is highly probable that the transmission of films will take precedence over the television of actual moving scenes during the early stages of commercial television. We must acknowledge the fine work of Baird and his associates, and we can reflect wth pride on the fact that great pioneering work

in television has been done in. this country. We shall: be extremely foolish at this stage to let other countries get ahead with systems of film television when we ourselves know so much about film scanning and cathode ray systems. Already the B.B.C, is satisfied that the film transmission of television is a good proposition for home entertainment. . | There are factories in this country turning out the specially designed cathode ray tubes used at both the receiving and transmitting ends of such systems, and I feel sure that during the next twelve months some remarkable developments will be made in the cathode ray

tube which is, after all, the vital link of a television system. The cathode ray tube is a sort of second cousin to the radio valve, and when we realise what amazing developments have been made in‘the valves since Professor Flemming = first -conceived the idea, we can appreciate the fact that there is plenty of room for development in cathode ray tubes.

American and German television experimenters are making great progress, but there is no reason why British engineers should lag behind. I feel that in only a year we shall have no cause to feel ashamed of our own progess in television transmission and reception.’ At the moment the great problem is to get plenty of detail in pictures and. to transmit’ this detail on a radio link. without: taking up too much space in the ether. I think that even the least technical will realise that the more detail you want to transmit in a picture the more: space you must take up in the broadcasting ether. This is space we can very ill afford, in view of the wave band limit, and the present chaotic conditions. For this reason, unless some radically new method of television transmission is devised, it is almost certain that this now form of entertainment will be broadcast .on the short or even the ultra-short waves, where there is infinitely more room to spare. For example, only 96 stations can+be comfortably accommodated on the present-day broadcast band extending from 200 to 550 metres; whereas on ‘the ultra-short waves, between 2 and 5 metres, no less than 900 stations could transmit without interference. It may transpire, as I prophesied many years ago. that eventually transmission on the electric light mains, or even the water pipes of the country, may supplement ordinary radio broadcasting as a means of home entertainment.. When the whole country is connected by vast electrical. grid wiring systems, it ‘will be a comparatively simple matter to transmit programmes by electric light mains.. Very probably there will be exchanges, so that the subscribers can switch on to various programmes. For the benefit of technical enthusiasts. it must be emphasised that the transmission over the electric light wires will be made with a high frequency system similar to radio broadcastings, and not with the low frequency sound system that was used in the very early days. I feel that if during the next year we make some real progress in transmitting programmes at radio frequency over the grid system, we shall have gone a long way to ensuring interference-free broadcasting entertainment for fothcoming generations.