A NEW "5.0.5."

Dominion, Volume 13, Issue 139, 8 March 1920, Page 7

A NEW "5.0.5."

NOVEL WIRELESS EMERGENCY CALLING DEVICE. Tho Marconi Wireless Telegraph Company have invented a new wireless emergency calling device, whorebv a ship in distress can ring alarm bells on other ships within wireless range. Experts who examined it declared that it held the promise of great success, and was likely to bo tho medium of immense benefit to those who go down to the sea in ships, especially in the poorer class of ships, as we shall show. One of the characteristics of wireless communication has been that, in order to ensure that the signals shall bo heard from any station which may be "calling un," an operator must be on duty wearing the usual telephone headpiece. Tho reason is that the sound produced in tho telephone by wireless signals/ received under normal conditions, is inaudible at a very short distance from the apparatus. Tho new emergency calling device, it is claimed, gets over that difficulty, and enables a .station, or ship, equipped with a special automatic transmitter key to call up any station within range which is fitted with a corresponding selective receiver • Tolay, even if the operator is not on duty "at that station. The ship in distress, say, wishes to send out tho special signal, which, it has been arranged, shall consist of n scries of Morse dots, on a six-hundred metre wave, sent at the rate or 180 dots per minute. Tho rate must be absolutely uniform, therefore the automatic transmitter has been invented.

The "calling up" is affected by a powerful bell, wheh starts ringing on tho ships that mnv bo called a few seconds after the key at the willing is pressed. Once the operator's attention is attracted, communication proceeds by wireless in the ordinary coune. One of the iimiortant uses of the device wilt, it is hoped, be to ensure general and immediate attention to emergency calls, such ns the "5.0.5."