The Process of Broadcasting

THE PROCESS OF BROADCASTING The actual process of broadcasting, though complicated in detail by the variety of the items broadcast and by their volume (which amounts for instance to about 74,00o transmission hours annually for the British broadcasting system), is simple enough in outline. Most of the performances take place in a studio, which is carefully arranged so as to give, for the necessarily small room, an acoustical condition that is pleasing to a musical judgment as applied to the receiver. This requires a certain amount of echo elimination, by drapery and otherwise (in British practice a fixed amount of natural echo with partial superposition of a control lable "artificial echo"). Speakers, singers and players address themselves to the microphone, and an expert operator in a control room, following closely the speech or music, continuously makes fine adjustments of the amount of electrical impulse modulating the transmitter to allow for changes of original sound volume, an operation necessitated by the fact that the transmitter is of fixed and limited power. The transmitting gear proper is usually sepa rate from the studio, and may be as far away as 70 or 8o miles, connected with the studio by a special line. Another class of broadcast which is of growing importance is the picking-up at the place of origin of public concerts, operas, plays and public speeches, as well as of ceremonies, crowd noises, sporting events, etc. This is done by a portable microphone gear connected, not necessarily by wire, to the control-room; the special in terest of these broadcasts to the listener is that they enable him to feel himself as a participant or member of the audience. In the case of music, large-scale performances are often, for psychologi cal as well as acoustic reasons, more successful as "outside" than as studio broadcasts; but, of course, public halls, churches, theatres, and opera stages, open spaces and so on, all present spe cial acoustic problems which have to be solved according to the special circumstances.

Of outstanding importance in the organization of broadcasting is the simultaneous broadcast, or "S.B." This involves a system of interconnected telephone lines by which a studio or other place of performance can be connected to as many transmitters as may be desirable or possible. Thus the London microphone may be connected to all stations of the British system for a news bulletin, and immediately afterwards all, or some, stations (London in cluded) may be similarly connected to a microphone installed in a Manchester concert hall ; or, again, the sound of the sea taken up by microphone on the shore at Plymouth may provide a back ground for a drama performed before the London microphone and broadcast by Plymouth, London and all other transmitters.

Needless to say, S.B. requires the closest timing and co-ordina tion over the whole system, and it is carried out most completely and successfully when all the stations of a country are under one management, as in Great Britain. In the United States and Canada the method is practised wherever a distributed network of stations happens to be controlled by a large corporation. In Ger many, until the unifying policy of the National-Socialist regime made itself felt, simultaneous broadcast was usually practised only between a main station and its relay stations considered as a group. The "wireless link" (i.e., the substitution of the telephone wire by a wireless telephone system) is sometimes employed in broadcasting where land line facilities are either unavailable or unsuitable.

Listening Problems.

The listener's end of the transmission system presents problems of its own. Private receiving sets are divided, conventionally rather than scientifically, into "crystal" and "valve" (vacuum tube) sets. The sounds that they generate in response to the excitation of their aerials are heard from either headphones or loud-speakers, the latter varying in power from small drawing-room instruments to large-scale installations capa ble of reaching crowds assembled in halls and open spaces. The receiving sets themselves vary in sensitiveness, selectivity and other qualities, according to design, workmanship, nature of aerial and earth employed. The crucial distinction in the nature of sets, though roughly coinciding with that between "crystal" and "valve," really turns upon the distance at which a station can be heard without extraneous interferences. The crystal set may now be regarded as obsolete.

There are two distinct conceptions of "listening," from the listener's point of view. On the one hand, there is the desire— which may arise from technical interest or from dissatisfaction with the local programme—to listen to far-away stations. This has produced the long-distance set, which is so sensitive as to be able to pick up r.5kw. stations as much as i,000 or 2,000 miles away, but which, from the very fact of this sensitivity, is more or less open both to local and remote electrical disturbances, such as those caused by "oscillation" (re-radiation from a nearby re ceiving set which, when mishandled, acts as a small transmitter), by heterodyning between stations, by "atmospherics," by har monics emitted by powerful W.T. stations, by the spark trans mitters still largely used by ships, and by industrial and domestic electrical appliances.

On the other hand, there are the listeners who are content with the programmes of the nearest station (which, as we have seen, do not in the least depend on that station's own artistic resources) either because they have little or no interest in the technical side of wireless telephony, or because the local programmes are artisti cally and otherwise satisfying. The interest of such listeners is concentrated upon the programme. The receiving apparatus that they need is simple, easily manageable, and owing to the nearness of the station and the consequent strength of its signals free from extraneous interference (other than purely local troubles, such as are apt to affect "all mains" receivers).

International Relay.

Public interest in the broadcast move ment tends to centre itself more and more on the programmes rather than on the means of receiving them. This brings forward new problems and prospects of extending, by co-operation between national, as well as by co-ordination of local and regional, broad casting stations, the field whence material for alternative pro grammes can be taken and locally re-broadcast. So far as Europe is concerned, this has been rendered possible by the rapid exten sion of modern long-distance telephony cables; and, given certain technical conditions and pre-arrangements, there has been ample proof that it is not difficult to carry out multiple relays involving a number of countries. Such relays have, in fact, become a habitual feature in the broadcasting programmes of many Euro pean transmitting stations.

World-wide broadcasting, on the contrary, involves either an enormous development of telephony lines of the highest grade over regions where maintenance is difficult if not impossible, or the use of the wireless link. Now the waves used in ordinary regional broadcasting, none too reliable even over continental distances, are useless over world-distances, but fortunately, another line of attack on the problem, namely the use of "short" waves (lengths 50-1om., frequencies 6000-30000kc/s) has proved increasingly successful. Most civilized countries have now set up world broadcasting services, and though these cannot as yet claim the certainty and the high quality of transmission of local services, the extension of the field of broadcast over the whole globe is bound to have important social, political and economic consequences. A further technical development, as yet em bryonic, is the use of `ultra-short' waves (lengths below io m., frequencies above 30000kc/s) with precisely the opposite object, namely, to increase the possibilities of very localized service and in particular, television.

Communal

Listening.—Although in civilized countries of the European type the great majority of listeners are individuals and families grouped round their own hearths, this is not the only form in which the broadcaster's output reaches the public. Another is the so-called `wireless exchange,' which in essence consists of a central receiving set connected by wire to sub scribers in their houses, inmates of hospitals and institutions, etc., who listen on their telephones or loudspeakers, as the case may be. A variant of the same scheme—which is, in fact, older than radio broadcasting—is the direct connection of such sub scribers, institutions, etc., to the source of performance with out the intervention of wireless transmission at all. Yet another form of collective listening is the loud-speaker in hotels, cafés, cinema theatres, open squares etc. ; here the audience is prac tically a public assembly, and hence this practice of "re-diffusion," if carried on without permission, has been held in many countries, Great Britain included, to constitute an infringement of perform ing right.

Organized communal listening promoted and controlled by the broadcasters or by local or national administrations is likely to have a considerable future, especially for populations of predom inantly rural type. In Russia, for example, it may be said to be the most important branch of broadcasting as practised, the in dividual listener being of much less account. The loud-speaker may operate in or in front of churches, mairies, schools or the like. A special type of communal listening is the religious service in which the sermon, or sometimes the service itself, is received and diffused in the smaller and scattered places of worship, many of which have only visiting clergy. Loud-speakers as such are frequently used to convey the voice of the officiating clergy.