Radio network emergency caller identification - uses random time staggering to prevent mutual blotting out of simultaneous emergency calls

摘要

A radio transmitter/receiver is for a network with a number of stations working with a central station on a common channel. an emergency cally device provides for the transmission of an emergency call from any station on pressing an emergency button, which ensures identification of the callers at the central station if more than one station radiates an emergency call at the same time. Each station automatically calls an emergency signal interrupted at intervals by its call sign. to facilitate identification of received call signs at the centre the time between call-signs identification signals is made variable to prevent permanent overlap. this may be effected by a random signal generator in the form of a shift register with feedback, which is automatically switched in on pressing the emergency button.