WHAT IS F.M,, AND DO LISTENERS WANT IT?

Press, Volume LXXXI, Issue 24749, 14 December 1945, Page 6

WHAT IS F.M,, AND DO LISTENERS WANT IT?

RADIO

[By a Staff Correspondent of tire “Sy«jpey Morning Herald.*’] (Published by Arrangement.)

Does any scientific discovery live up to the early reputation claimed for it? That question is asked to-day of what is called by radio men frequency modulation, or F.M., a broadcasting method new to Australia, f: ■ The answer seems.to-be that in this case the discovery does livd up to most of its claims! - But F.M. does not make your present -receiving set obsolete, nor does it - directly affect existing methods of broadcasting.It will allow more stations to operate without interference, because it has been given a different wave band. It is as distinct from other wave bands as the present short-wave band is from the broadcast one. To receive short wave you need a special kind of set, usually incorporated by special fittings in the ordinary one. To receive F.M. broadcasts, you would need other special fittings, including two or possibly three speakers. The fittings can be built in, as they are in combination sets now sold in the United States. Use in America There are now about 50 F.M. transmitters in America, and the comparatively small number of 500,000 receivers, most of them also receiving broadcast programmes, has been sold. So "at the'moment, owning an F.M. receiver is rather exclusive. Chief advantages which those owners enjoy are that the F.M. programmes eliminate the usual sources of interference and are extremely natural to hear. The strongest F.M. station on any one channel always predominates, so that a number of stations cannot be heard together, as they sometimes can with the ordinary receiver. Because F.M. operates on a'different principle from the present system it ignores electrical interference, static, and the welter of man-made noises which so often ruin broadcast reception in cities. The noises made by lilts, trams, and the like are a kind of broadcast of the same character as a station programme. For naturalness, F.M. again scores for its wide range. Sounds that can be heard are measured for their pitch in' cycles.-' The lowest sound you can hear is about 30 cycles, the highest about-17,000. Within that spread, comes the human voice range of-80 to about 850 cycles. F.M. broadcasting can cover most of the audible range of sounds, where the present system gives only about one-third of -them. F.M. transmissions would bring the speaker or orchestra right into the room. It would cover every noise from the roof-shaking organ bass to. the scrape of a fiddle bow. . '

Leopold Stokowski, noted conductor, was of the opinion that a range of 13,000 cycles . was necessary for adequate transmission of orchestral music, whereas the range, of the present-type receiver is .far narrower.

An Australian report, printed on Wednesday, showed that Mr R. J. F. Boyer chairman of the Australian Broadcasting Commission, giving evidence before the Parliamentary Committee on Broadcasting, said that if frequency modulation were introduced, receiving sets now in use’would become obsolete; but the present receiving and transmit- : ting technique known as radio modulation, might be so far improved as to avoid this disturbance. Mr Boyer’s evidence caused no little stir It provoked, for instarice, the protest of a manufacturer • against opening to the press technical evidence which had caused “tremendous damage to the radio trade.” This protest and the committee’s reception of it are reported in this issue of “The Press.” The following article describes the frequency modulation system.

-However, ability to hear very high sounds is restricted to certain animals and the very yo\mg, the range decreasing with age. Again, above a certain level the only V things reproduced are noises like key . v jingles, footsteps, and non-musical noises from instruments—resin squeaks and the air rush from flutes and bassoons. Listening to F.M. broadcasts in Australia is likely to be exclusive in quite another direction. . Unlike present transmitters, which have a day-time range of several hundred miles and a night range of perhaps thousands. F.M. transmitters do not reach farther than the horizon. High buildings or hills can blanket the broadcast or cause distortion. A ’ range of 50 to 60 miles is possible ' under favourable conditions. So, to cover country areas, it would be necessary to have, one or more relay stations in the centre of each settled area or country town, unless these are close. The cost of broadcasting would, ‘ therefore, be much increased. The 1 cost of the receiving set also would be higher. Compared with the wide sound ■ range possible under F.M.. present : broadcasting covers only about onethird of audible sounds. Neve'rthe- - less, experience and various surveys ; have shown that when the upper limit ■' of even that restricted range is approached, most listeners use the tone • control to cut out anything higher - than what is called a “mellow” tone -

N American Discovery £ F.M. is the discovery of Major E. H ■ Armstrong, American radio engineer! who began work on it in 1914 in an - attempt to find an antidote for static. ■ After he introduced it in a paper before the American Institute of Radio Engineers in 1935 it was increasingly, exploited on a commercial scale. • its * chief interest for the . United States lies in the possibility of enabling ‘ - more cofnmercial stations to operate - without interfering with one another.- • J It is clear there are some definite idisadvantages in F.M. It is a moot point whether or hot ■= the i faithfulness of FJVI. reproduction -v is so greatly desired that listeners will ' pay more for it. s Many could not tell the difference, Vl many do hot care as long as they can. for example, hear the result of the last race. Distorted or not, that kind of : news is still audible on many a set a - radio doctor would say is in the limt ' stages of decay. * Most people are concerned with : - radio for the thread of a serial, an item of news, or other entertainment - the present transmissions adequately' provide. They might or might not be . able to appreciate an'improvement v In other, words, does the listener ■ want F.M.? If he does, it will most ■ , probably develop along the lines now ■ followed in the United States, where V 1 it is provided alongside the present system of broadcasting. , -