RADIO PROBLEMS

New Zealand Herald, Volume LXX, Issue 21552, 25 July 1933, Page 11

RADIO PROBLEMS

EMPIRE BROADCASTS ENGINEERS' DIFFICULTIES THE SIGNALS THAT STRAY [from our own correspondent] SYDNEY, July 20 Tho problems encountered by the British Broadcasting Corporation in their Empire transmission, as reported by a cablegram last week, aro not fundamentally new, according to Australian physicists, although they aro now in their application to Empire broadcasts. According to tho cablegrams, tho transmission to Australia misses New Zealand, which easily picks up tho signals designed for West Africa. Canada picks up tlio 25-nietro signal destined for Australia when she ought to bo receiving tho 19-metre broadcast. Mr. G. H. Munro, physicist attached to tho Radio Research Board of Australia, said that although those Empire transmissions were not strictly sent out oil a beam, they were broadcast from directive aerials. The problems of the 8.8.C. engineers were apparently duo to tho fact that tho signals strayed from tho paths into which they were direct. The effect of using a directional aerial was that the signals were very much stronger in tho path in which they were sent. Long-distance transmissions, however, depended on tho amount of day and night in the path of tho signals, and this varied at different times of the year. Because of thoso variations, it was difficult to predict what wave-lengths would bo most' suitable for reception in a distant land. "For some reason," said Mr. Munro, Paris broadcast signals aro stronger in Australia than thoso of London, but if you look at tho globe you will see that tho path of London signals to Australia is much further north than that of Paris, and tho ray goes nearer to tho North Polo. Tho direct line from London to New Zealand is still more northerly. That probably explains why tho programmes sent to Australia, by the British Broadcasting Commission aro not well received in New Zealand. Thoy meet different conditions on the way. "As I read the cablegram, both Canada and New Zealand aro receiving stray signals away from tho directional path". Canada receives tho Australian signal sent across Europe, and not the other one, which follows a path across Canada, Now Zealand gets tho West African signal, which is sent out in an almost southerly direction and should miss tho Dominion. The answer to that seems to be that the directional system is not 100 per cent efficient, and that conditions may happen to favour tlio stray signals." It is pointed out that the 8.8.C. engineers aro now working on 49 metres in tho hope that this wave-length will suit both Australia and Now Zealand. This channel has been very popular and effective in other parts of th 6 world, notably tho United States and Asiatic countries, whoso broadcasts have been well received in Australia.