Research Into Wireless Waves and Broadcasting

Poverty Bay Herald, Volume LX, Issue 18193, 14 September 1933, Page 10

Research Into Wireless Waves and Broadcasting

MELBOURNE, August IS. DAPEES ..uu.: ‘various subjects of re.search connected .with wireless wiivet- ami broadcasting were read yesterday by some of the visiting scientists who arc iu conference in -Melbourne. A great deal of original work or this kind is being done here, and it was confidently stated at the conference yesterday that in knowledge of the action of atmospheric disturbances Australia was the leading country in the world.

iu a paper on '‘Atmospherics in Australia,” Mr. 0. H. Munro said this subject was more important to Australia owing to its remoteness than to most other countries. In order to be able to predict atmospheric interferences'at any place on any wave length it was necessary to know the times and places of occurrence, intensity ot origin and the variation in their intensity, with the distance of their origin from the receiver. These tasks, which were being undertaken by the Kadio Research Board, had met with gratifying success, and the information oil the subject was now more complete than for any other country in the world. By means ol a wundc.iful instrument known as the cathode ray direction tinder each atmospheric disturbance was registered automatically as a luminous line oil a circular scale, showing both the direction and intensity of the disturbance. The work in Australia had shown for the lirst time 1 hat by this means the distance away of the source of the atmospherics could be estimated, this was done by plotting the records of two observing points, namely, Laverton and Alt. Stroiulo (Canberra). Places could be accurately located up to 1(11)0 miles. Investigation had shown that, all atmospherics were due to lightning, or fulgur, the Latin name for lightning. An instrument at JVlt. Stromlo kept a continuous .record ot the direction of till fulgur sources over a wide region. The. most important application of this data was in the prediction of interference with broadcasting so as to enable the best choice to be made of sites, wave lengths and power for broadcasting transmitters. " The frequency of atmospherics was greater towards the equator, and increased in summer with decrease in latitude. The average duration of a source was much greater over sea than over land, and the daily variation of occurrence and activity was much less pronounced for sea sources. Land .sources nearly all occurred between Ufa.in. and 10 p.tu. local time.

A paper' by Dr. D. F. M.artyn on “Giouml and JSkv Waves un Broadcasting Frequencies” showed that reception of signals on broadcasting frequencies was caused by an earth wave and tin upper atmosphere wave. It was possible to forecast the intensity of u wireless wave for various frequencies. In discussing broadcast stations Air. W. .T. Wark said that in a well-de-signed station the distances tit which fading and interference became intolerable should coincide. Mr. Walk assumed a certain strength ol signal as being satisfactory and then discussed at what distance from the transmitting station this strength would be obtained for difi'ereut wave lengths, ground conductivities and geographical locations. In discussion, Mr A. L. Gree.n showed that the propagation of a wireless wave depended not so much on the conductivity of the ground as on the general topography. Wireless waves did not travel so well over mountainous or wooded country.

Mr. 11. Boswell described how the progress of low-pressure areas . across the. Tasman Sea had been followed by observation of atmospherics recorded in Canberra mid Xew Zealand. The detection of low-pressure areas from the observations of atmospherics could supplement the weather information generally supplied by steamers.