WIRELESS NEWS

Press, Volume LXIII, Issue 19144, 29 October 1927, Page 10

WIRELESS NEWS

(By Listener.)

At the end of August the final link of the chain of Imperial radio communication was forged •with the opening of the beam service between England and India. The chain now includes special transmitting and receiving stations at each end between Brilaiu and Australia. Canada, South Africa, and India, so that the whole of the Empire is linked up with the Home Country, and individual parts of the Empire are linked closer together. * * Over 1900 schools in Davcntry and London are equipped with radio receiving apparatus, according to a recent report. Twenty-eight .schools in Glasgow and 100 in Manchester participate in radio. Pupils in schools equipped with radio receiving apparatus are provided with special manuals at reduced cost, which enable them to ftudy foreign languages through the aid of the radio courses. It is also made known that the British Broadcasting Company maintains thirtv technical radio experts to keep the radio equipment in the schools in operating order. * * The Department of Agriculture in the United States has brought forward an extensive service for the American farmer, and this is the result, of special study on the Department's behalf. The programme includes housekeeping information, such as marketing, cooking, gardening, etc. A radio farm school gives practical information on poultry, dairying, livestock, crops and soils, farm economics and much other useful information. A special feature is the manner of offering this information. Much is done in the form of a dialogue between two people, one asking questions and the other giving the information in reply -to the questions, and in this way the interest is sustained. BIG PUBLICITY CAMPAIGN. RADIO IN CARNIVAL WEEK. A big effort will be made throughout Canterbury during Carnival Week' to incrca.se the popularity of radio, particularly among farmers. The Broadcasting Company is arranging for an extensive advertising campaign drawing attention to the advantages of radio, and will also have 3YA "on the air'' practically from breakfast time till midnight each day. It is intended to open each day's programme with a breakfast-time session, when information will he broadcast as to the weather in Christchurch, the day's fixtures, the race' card for the day, and news items of general interest. The broadcasting or the races will include as additional features all the band items and a review of the fashions on the lawn, this latter broadcast being by a lady "editor" specially engaged for this purpose. In the evening there will he a dinner-hour session, when the day's racing will be reviewed by Mr Allardyce and a talk given on prospective form for the following day s racing. This session will also include musical ■items. Special artists are being engaged for the evening sessions proper, and from 9.30 - onwards till 11.30 or midnight there will be a broadcast of dance musio for the benefit of those who will bo giving private dances in their homes. There will be 'a relay' of the Jockey Club's ball, and a description will be given of the frocks worn by those attending this popular fixture. The radio traders are co-operating with the broadcasting Company with a view to making the week a big "boost" for radio, and it is hoped that as a result of the publicity which radio will receive that there will be a substantia] increase in the licenses for November.

EXPERTS CONFER.

THE WASHINGTON CONFERENCE A world conference is sitting at Washington discussing radio legislation problems. Representatives of 51 countries have assembled under the presidency of the well-known Mr Hoover, head of the Department of Commerce. The conference is a very important one, and the discussions are expected to last six or eight weeks. One may wonder what can occupy the delegates for such a long time, and it is interesting 'to see how we are likely to be affected by the. conference decisions. Regulating Radio Traffic. The object of the conference is to draw up a code of laws for the regulation of all kinds of radio activities in every country. That is so far as all countries are concerned. The domestic problems of individual countries will not be legislated for at "Washington. Those problems will be left for the local Legislatures. But there are many phases of radio that are international .in character. The use of radio by ships and the conditions under which the S.O.S. signal should be used and obeyed, for instance, must have a common and well-known basis in all countries. Thus the eaptain of a ship of any country in any ocean near any territory knows that the approved means of calling for assistance in time of distress or danger will meet with a ready response. This S.O.S. call procedure was the cause of the first international radio conference which was held in London in 1913. That, conference dealt with radio in all its phases then known. But there was no broadcasting in those days. Thus the laws agreed to in 1913 arc either obsolete or incomplete for pres-ent-day practice. Wave Lengths Will be Agreed To. The important aspect will be the apportioning of wave lengths for broadcasting and for other purposes. Different services such as ship transmission, aircraft transmission, broadcasting service, etc., must' have certain wave-lengths set aside, so that interference will not result. For instance, the wave length of 600 metres is reserved for the use of ships—it cannot be used for broadcasting. The necessity is manifest, therefore, for a common international understanding on the points. There has been no understanding hitherto on the cjuestion of broadcasting wave lengths. Hence there is nothing to prevent adjacent countries using the same wave lengths, to the confusion and disadvantage of the services in the respective countries. Such an undesirable state of affairs has actually occurred already between Canada and the United States and in Europe. There are many more subjects concerning commercial and experimental wireless on which the decisions of the conference will affect New Zealand, but probably the question of wave lengths for broadcasting is the most interesting.

Notes From Far and Near.

WAR ON STATIC. SOME PREVENTION DEVICES. The chief reason that it is so difficult, to eliminate static is that it comes from so many different sources of disturbance. It is as though Nature were sending from thousands of radio stations of her own, tuned to all possible wave lengths and frequently of great power. So the result is, since static is coming in on all wave lengths, that no matter where we tunc our receiving apparatus it is impossible to avoid it. The only difference between the static waves, and the waves from radio stations is that the static is highly damped; that is, very broadly tuned, as compared with the usual ether waves. This enables sharply tuned receivers to discriminate to a certain extent in favour of the' radio signals, since the sharper the receiver tuning the narrower the baud of static which is being received. But even at best this affords very little help. Perhaps h. -vord or two as to the cause of static may not be amiss. It is, we believe, in general, caused by electrical, discharges in the atmosphere; much of it undoubtedly comes from lightning and non-luminous discharges in the thunder clouds. But it may also probably originate where any two bodies of air at different electrical potentials come together. In regard to non-luminous discharges from thunder clouds, it has been suggested in England that the cloud may discharge quite as readily to the upper conducting atmospheric layers as to the earth. Even though the distance may be so much greater, the diminution of air pressure with the height would render the discharge so easy that it is extremely likely that such discharges may take place even without luminous effects. Watson Watt, in analysing the records of European radio stations in order to determine the causes of static, has concluded that in only about 35 per cent, of the cases given could thunderstorms be identified "as the sources of these disturbances, but that in 75 per cent, the sources were rain areas of some kind. Hundreds, and perhaps thousands, of devices have been produced by various people which, it was hoped, would overcome static. When these have been thoroughly tested, however, while some have been slightly useful, nono have proved cure-alls. . The fact is, it is rather easy to imagine that static has been eliminated when experiments are being made with weak static and rather strong signals, for it is only necessary to cut down both equally in order to make static disappear. If a record had been kept of the time of year in these inventions it would usually be found that they were developed during the Autumn and Winter 1 and finally came to grief under the high static of the following Summer. Most of these antistatic devices may be divided into the following classes: Directional reception devices, audio frequency tuning devices, signal limiting devices and balanced circuits. Directional reception, at least), .as faras long-wave radio-telegraphy is concerned, is certainly the most effective means of combating static which we have at present. It is particularly useful where the reception is from overseas, since most of the static comes from the.land side and roughly from the opposite direction of the signal. This principle is employed in the Beverage antenna, as used by the Radio Corporation of America and others, for longwave transoceanic reception, and in the unidirectional combination of loop and antenna. Some of these antennae are often many miles long. Audio frequency tuning is somewhat useful in the reception of code, on account of the difference in tone of the signals and the static, but obviously cannot be.used in broadcasting reception where all the musical tones must be equally received. In limiting devices, by means of vacuum tubes or by other means, the maximum strength of signal which can pass through the receiver is limited. This is an idea which has formed the basis for a very large number of static-re-ducing inventions, and it does indeed bring the static down to the strength of the signal. But the unfortunate fact is that when the strong static is coming in, the receiver is practically dead, so that at that moment no signal is received, and in the case of code, dots drop out and holes are left in the dashes. A number of years ago a rather complicated form of static and interference eliminator was devised which worked 6omewhat on the principle of the combination lock, in which only the impulses which tame in a definite combination could get through the receiver. But in this ease, like the limiting devices, static also destroyed the clearness of the signal. None of the arrangements thus far mentioned offers any hope for a real cure of static, and unless some brandnew idea is developed we cannot see any definite prospect of getting rid of it entirely. At present, the best .way of avoiding trouble is to make the signal stronger than the static. Strong signals may be obtained either by using great power or by getting close to the sending station. So the simplest means of avoiding static interference is to make as much use as possible of the local stations. For except in rare instances, reception over a distance of but a few miles offers the only possibility of perfect enjoyment of a fine musical programme.

The conquering of static by high power at the sending station is evidently limited by economic considerations, for doubling the power of a sending station only increases the amplitude of its waves by about one and one-half times, since the amplitude increases as the square root of the power. Therefore, at a distance of several hundred miles, any probable increase in station power will not be able to drown out static, when it is verv severe.

It. must be concluded, therefore, that static seems to have the best of us, except when we are close to the transmitting station, because with all the powers of Nature behind it, it will always at times be able to drown out our human efforts.