RADIO NOTES.

Pahiatua Herald, Volume XLI, Issue 12454, 21 September 1933, Page 3

RADIO NOTES.

RECEPTION IN U.S.A. Official investigation in the U.S.A. reveals that roughly 90 per cent, of the total number of listeners are able to receive broadcasts from numerous local stations without any sign of interference. These favourable conditions are achieved largely by not allowing more than 352 out of 600 stations to operate at the same time. Previously 565 transmitters Were on the air together, thus causing mutual hetero-dyning. COMPOSERS v. BROADCASTERS: The war between broadcasters and composers in the United States is responsible for the production of some, startling figures. The fact is quoted that '‘Ramona/' a popular song- 'hit of 192.7, ran into 1.750,000 copies,, while to-day, clue to the influence of broadcasting, a song is accredited a real hit if it runs to 100,000 copies. 11l 1932 the sale of gramophone records dropped .to onefortieth of what it was in 1927. The •microphone must share the responsibility for this phenomenal drop, but surely it cannot he blamed for all of it. What of the effects of the depression upon luxury purchases in U.S.A. ? AUSTRALIA’S LICENSE RANKING. Australia- claims to have a larger percentage of listeners than anv other Dominion. and: considers it ranks sixth m the world for proportion of licenses to population. MOONLIGHT AND STATIC. Does moonlight cause static? We do not know but reception on one or two bright moonlight nights lately certainly lends colour to tile statement. Even 2>YA could oniv be heard intermittently above a barrage ot noise. BROADCASTS FROM, DAVENTRY. During recent weeks the British Broadcasting Company has been carly ing out. extensive tests in c-onnec-U/n with the transmissions intended for the Australasian zone. Numerous reports on reception m Aus- . have been reaching London, affording reliable data for the engineers at Davenh-y. Following the receipt of. these reports, it would appear that some re-arrangement of the aerial systems at the transmitters has been made. In fact, it would appear that tests are being still made. Whether the changes made are directly responsible, or whether seasonal conditions are doing their part, it, is not known, but a. rather pleasing improvement has been noticeable so far as the direct transmission for the Australian zone 1/ concerned. Signals are very weak, if audible, at 4.45 p.m., the present opening time, but have been up to R, by 6 p.m. The hour is not convenient for regular listening, but the above reception was noted re-c-ently. The time of transmissions will be changed to 5.30 p.m. till < .30 p.m. in a .few days for the month of September. GSD is well received most mornings between « a. ill. and 111 a.m. GSB at the same time is seldom more than R 4. Neither of the other frequencies of the Empire stations has been heard recently. H E A'VISIDE LAYER. EFFECT ON BROADCASTING. At the beginning of the present century scientists reached the conclusion that there must be a region m the upper part of the earth's atmosphere which acts as a fairly good conductor of electricity, writes , Baker in the “Wireless Weekly-. This suggestion was made bv Oliver Heaviside in 1902. to explain certain phenomena nqt connected with radio, such as variations of the earths magnetic field. Later work has' shown that all these phenomena do have important influences on radio. In 1912 it was suggested by Eccles that this conducting layer, called the Heaviside layer, would act as a guide to confine the energy of radio transmission, causing it to bend around the earth instead of passing out into space to be lost. The layer might be regarded as a mirror which reflected the radio waves back to the earth. It has since appeared that sharp reflections will only occur for long waves • shorter waves penetrate fur” ther into the layer and are bent around and bac-k to earth gradually- The effect at the ground is as if the mirror were higher for shorter wave-lengths. For long waves, the height is at the lower .boundary of Ibe layer, for very short waves it will be at the most intensely conducting part of the layer. If the waves are short enough, rays starting out at a large inclination to the ground will not he turned back at all, while those more nearly horizontal will be brought down at a considerable distance, mere will then be a region in which practically no signal is obtained. I be distance to the point where the signal reappears is called the skip distance. In the- case of such wavelengths as are used for Beam services, this skip distance amounts to some thousands of miles. The Heaviside layer appears to be produced mostly by the absorption ol ultra-voilet light from the sun. tiertain gases in the atmosphere are split up into electrons and positive ions The ions and electrons have a tendency to recombine, and the layer. will be in a steady state when *ls many recombine as are formed in a- given time. After sunset the formation of ions ceases, so that tile amount of ionisation p resell l gradually, decreases. As the recombination is greater at lower heights, the effect is as if the lower boundary ot the layer rose. At sunrise it rails again ; but during the davtime and during the night it will he fairs' ■ S J-/ iK J v • b"t having a different height by day from that by night.