WIRELESS WONDERS

Hokitika Guardian, 13 March 1925, Page 4

WIRELESS WONDERS

empire broadcasting

LONDON, December 18.

Australia is likely to he so closely concerned in the development of wireless telegraphy and telephony in the near future that no apology is needed for supplementing the cabled, summary already published ill Australia, of the revelations made by Signor Marconi in the paper he rend before the Royal Society of Arts last week. There is the more reason for returning to the subject hv mail when one rememljors the conservatism of the scientist which

-••arconi has always shown. Throughout his career Signor Marconi has never once lent his name ti'i exaggerated claims. In this way he has never let the public down with announcements of possibilities which, experimentally, had not already been achieved. For these reasons his most recent announcement of the marvellous strides recently made with the beam wireless system will he read with the greatest interest. Signor Marconi in his paper showed in the first place that the use of shortwave beam transmission is not a new discovery. He recalled the fact that during his earliest experiments carried out in England over 28 years ago he was able to show to the late Sir William Precce, then engineer-in-chief of the Post-office, the transmission and reception of intelligible signals over a distance of I:,‘ miles by means of an elementary beam system employing very short .waves and reflectors, whilst, curiously enough, by means of the antenna or elevated wire system, utilising much longer waves, he could only at that time get results over a distance of half a mile. The progress subsequently made with the non-diree-tional long-wave system was, however, so rapid and the results so immediately applicable to practical purposes, that it very soon became and still remained what might he called a standard system. SECRECY AND ECONOMY. Most people now agreed with him that wireless waves were lar too valuable to. he always broadcasted in all directions. Though he could well understand the utility of the non-direc-jtional s'tations for many naval and marine purposes and for broadcasting for ordinary efficient communication between fixed places, or between one country and another, the right and logical thing to do, if possible both from the point of view of secrecy and economy, was to concentrate all the radiated energy into a bean. l , directed towards the country or place with which it was desired to communicate.

Signor Marconi went on to describe the series of investigations commenced last August between Pohlhu, 'Cornwall, and the yacht Electra. with the object ol discovering means of overcoming the limitation of working hours brought about by daylight, and whether the reflectors used in the “ beam ” fystem would give the expected increase of signal strength over long distances. The yacht proceeded to Spain, .Madeira, Italy, Messina. Crete, and lieyroul, in Syria, returning to Naples, via Athens. At Madeira it was ascertained that a reflector at the transmitting station increased the strength of the received signals in accordance with the calculations, hut when a 92metre wave-length was used the daylight range was still only slightly augmented. Later, in the Atlantic and Mediterranean, comoarative tests wore carefully made with shorter wavelengths of 92. tit). 17. and 32 metres respectively. The lest- at once showed that the daylight range of practical communication over long distances ini ceased very rapidly as the wave-length was reduced. ’ The tests were continued over two months, in different places, and all observations confirmed that the daylight absorption decreased very rapidly as the wave-lengths were shortened progressively from 100 metres to 3"

AUSTRALIAN KX PER I M ENTS. In October last transmission experi- . ments were carried out on a 32-metre, wave from I’oldhu to specially-installed receivers at .Montreal, New York, Rio de Janierio, Buenos Ayres, anil Sydney. Although the power utilised at Pohlhu was only 12 kilowatts, it was at once found possible to transmit, signals and mesages to New York, Buenos Ayres, and Rio, even whim the whole of the great circle trade separating these places from Pohlhu was exposed to daylight. During a complete day, j transmission at fixed intervals to Sydney revealed that that station was able) to receive the Pohlhu -signals for 33% hours of the 2-1. During November I signals transmitted on a 51-metre wave length from a low-power station in Australia were successfully received in England. During (he past ten days trials had continued from Pohlhu with Canada, the United States, Brazil, Argentine, Australia and, for the first time, with Bombay and Karachi in India, and Cape Town in South Africa. The power used was to kilowatts. “’I he results have fully confirmed my expectations in regard to the behaviour of the various wave lengths over such great distances,” Signor .Marconi added, "and I have no doubt that the information gained will render possible the installation of comparatively low-power stations capable of establishing and maintaining commercial services by day and by night between England and the most distant parts of the globe. The low cost, of this system both in capital and running expenses, compared with that of the ex-

isting type of stations, must prove to lie very great, and should bring about the possibility of a reduction in telegraph rates for all long-distance communications, besides making direct communication with some of the smaller outposts of the Empire commercialIv remunerative.

“ 1 am now firmly convinced that the beam stations employing only a small fraction of this .power and much lower and fewer masts, will lie aide to communicate at practically any time with any' part of the Empire, and I cannot refrain from expressing my strong personal opinion that these powerful long-wave stations will soon he found to lie uneconomical and comparatively inefficient in so far as longdistance commercial communications are concerned. What remains now J n

be done is to complete the systematicstudy of these waves, especially in regard to their transit or propagation through space. They open up what I believe will prove to be a most fertile field for the investigator, and an entirely new horizon to our view.

‘T do not propose at this time to attempt to suggest any theories or scien-

i tifie explanation of the results of the results obtained. For some time the technical side of the art lias been well ahead of theory. Although we have, or believe we have, all the necessary data for the generation, radiation, and reception of electrical waves, as at present utilised for long-distance communications, we are still far from possessing anything approaching an exact knowledge of the conditions governing the propagation of these waves through space. If we had, we might, perhaps have known before this that a wave about 30 metres long, utilising only 9 kilowatts in an aerial, could successfully travel to Australia and South America during daylight, and there reproduce easily decipherable telegraphic signals. AMATEURS’ SERVICE. “ All the civilised world is now in-: c terested in what is called broadcasting. The results obtained bv amateurs have 1

often been of great value in helping us to come to somewhat 'better understanding of the phenomena involved, and 1 might remind you that amateurs have recently been able to carry out two way communication with Australia and New Zealand for brief periods. ‘'lt is jilso quite reasonable to expect that it will soon be possible for an important spteecli to be broadcasted even to the most distant parts of the Empire, irrespective ns to whether it is made during daytime or darkness. The wireless transmission of pictures has already been effectively realised bewteen New York and London. One would have to very bold indeed to forecast ivliat may be the future limitations of radio transmission.”

In conclusion Signor Marconi thanked the numerous engineers and experts in Canada, the United States, Brazil, the Argentine llepublie, the Cape, .India, and last, but not least, Australia, for their most valuable co-

operation in designing and working receivers. and in keeping long watches for the purpose of measuring the strength of the signals received from j’oldliu in their resuective countries.