Short Wave Broadcasting will Link the World

Radio Record, Volume II, Issue 7, 31 August 1928, Page 32

Short Wave Broadcasting will Link the World

ALTHOUGH still in the experimental stages, transoceanic broadcasting is a definite development of the future,.and the time is not far away when Antipodean listeners will be able to tune in to London, New York, Paris, or any of the great cities of the world (states "Popular Radio" (Aus.). For the past few months the British Broadcasting Corporation has been conducting a series of experiments in order to explore channels which might possibly lead to a system of regular programmes overseas. Up. to the present, according to H. Jeffree Cooper, chief engineer of the British Broadcasting Corporation, it is apparent that the future of a service of this nature must depend upon a solution of the problem of good reception

rather than upon changes at the transmitting end; for such service, to be of real benefit, must be ultimately received sufliciently free from atmospherics, fading, and other interruptions to enable .it to be rebroadcast with 2» quality comparable with that of the local station’s output. N addition to Brituin’s dream of broadeasting the programmes from the Home Country to the far-flung British colonies, the 55W experiments are also aimed ut establishing an exchange of programmes with the United States. OR several months past the 5SW short-wave signals have been received and monitored in New York and Schenectady, for the purpose of studying the signal strength, the intelligibility, the fading and other character-

istic of the transoceanic broadcasting relay service. EW York and Schenectady are 200 kilometres apart. The results at both these receiving points have been about the same. The 5SW signals have been intercepted by various professional and amateur radio men, and rebroadcast on several occasions when conditions have been most favourable. WHILE the short-wave signuls froin Chelmsford are being intercepted by radio amateurs employing conveltional short-wave receivers and aerials, the results obtained are by no meuus reliable under such conditions and limitations. NDEED, the reception of the present signals calls for laboratory technique of the highest order; and even in the future when improvements are certain to be effected at the transmitting end,. it will still be necessary to employ special equipment located at favourable points. R. Goldsmith states that a decided revision of the transmitter is necessary, together with the installation of special antennae and receiving sets in the United States before reliable rebroadcasting can take place, In the way of transmitter revision, the present power is probably insufficient for spanning the ocean, although power by itself is not the predominant factor in short-wave transmission. [¥ the signal strength varies of the _ order of 1000 to 1, which is often the case in such operation, due to fading,

the signal strength comes in pounding one moment, only to fade to a whisper the next. ENCH additional power alone’ can only serve to ruise the entire range of signal level, although the wide discrepancy between high and low points may even be accentuated, resuling in further problems. It is the amelioration of fading, rather than greater signul strength, which is desired. T is necessary to employ a directional type antenna at the receiving end, in order to effect maximum interception of the desired signal, to the more or less complete exclusion of other signals and parasitic disturbances. Also, the receiving set must include some. means of neutralising such residual fading as may remain in the transmission, so as to maintain a satisfactory signal level at all times.