WIRELESS TELEPHONY.

Taranaki Daily News, 24 April 1920, Page 11

WIRELESS TELEPHONY.

ITS POSSIBILITIES FOR NEW' ZEALAND. A MINISTERIAL STATEMENT. The T , oshTmter-Orr 3r 'il (Mr. Coaies) offered some remarks ;,, 1 the possibility of establishing telephonic communication between i -.he North and South Islands. Tips Minister saM Hint ho hud boon conferring with officers of the Post and Telegraph Department to see whether it would ho possible for an experiment in wireless telephony to be made between Wellington and Christchurch, and he had a report before him from the chief telegraph engineer (Mr. E. A. Shrimpton). "Though considerable advancement has been made in the development of wireloss telephony," said Mr. Coa*-v "it seems that most of the practical ,rork done has teen confined to communications over short'distances, and to the transmission of only one telephone message at a time between the two wireless stations involved. Telephone communication between the North and South Islands of New Zealand could not be met by such means, as such a service would soon demand the simultaneous transmission of several tele-' phone communications. Reports show that there are, however, other developments of wireless telephony which give promise of meeting the, problem mentioned. One of these developments is known ns multiplex telephony. It involves one ordinary wire telephone circuit, over which, by the use of wireless apparatus, and the application of wireless principles, several simultaneous telephone conversations may be carried on. The second development may be called multiplex wireloss telephony." It achieves the same result without the use of wires Like multiplex telephony, it has given practical results, but cannot yet be said to be a practical proposition.' It is the result of a special application of wireless receiving valves used with what arc known as heterodyne circuits. By utilising the effects of resonance and periodic interference, the receiving station is able to ingeniously discriminate between electric waves of varying frequency each carrying, super-imposed upon it, the delicate modulations whichconstitute sound waves. These developments cannot be introduced into practical telephony until much greater reliability, freedom from changes in adjustment, and variations in volume are assured. Unfortunately, this stage has not yet been reached, and, for these reasons, the field of wireless telegraphy and telephony is largely confined to telegraph communication between isolated points, for the connection of which wireless is peculiarly suited."