Ultra-Short Waves Used In Radio Telephone

Poverty Bay Herald, Volume LX, Issue 18205, 28 September 1933, Page 10

Ultra-Short Waves Used In Radio Telephone

SYDNEY, Sept. 15. A MAY application of ultra-short wave telephony was demonstrated yesterday by Mr. Don 11 Knock at the offices of 1 1 lie “Australian h'acbo Nous.” Mr. Knock and several anui l cur radio experimenters have been working with an apparatus which; it is claimed, may replace the usual telephones for inter-office cominunication. The'•principle lias been applied to other purposes in oversea countries. Since the range can be limited to various distances up to 2UO miles, the principle could be of particular utility for such purposes as private communication between an aeroplane and the ground, between the leader and other pilots of a squadron, or between the flagship and other vessels of u fleet. In warlike operations secrecy could be maintained by the use of suitable wavelengths and by limiting power, for example, m a fleet at sea. so as to allow “horizon range’’ only. “The Police Department,” said Mr. Knock, “is co-operating in our experiments with the object of devising suitable equipment for patrol-ear work. Bv such means police headquarters could maintain direct voice communication with police cars.” Mr. Knock has conducted experiments in particular with the officer'-in-c.harge of the police wireless patrols, Mr. W. Salmon, and with Air. S. McGuire. The whole of the equipment can be mounted on a camera tripod, requiring a power of not more than three watts (less thau that of the average house light). An earlier radio device, the “superrogeuerativc receiver” has been revived and applied to ultra-short >va v cs (of 5-metre length). A duplex telephone circuit is produced, which obviates the necessity of switching oil the transmitter while receiving a reply. At yesterday’s demonstration Mr. Salmon, speaking at police headquarters, could be heard very distinctly from a George-stroot office, and Mr. McGuire’s voice, from Ross bay, was clearly audible.