04462022 is referenced by 49 patents and cites 6 patents.

A wireless security system in which a sensor for detecting a security violation is provided with a radio frequency transmitter adapted to excite the receiver of a control unit at a different location, the transmitter of the sensor radiating a signal responsive to the occurrence of a security violation. The sensor also having means to periodically excite the transmitter after the lapse of a period of time to indicate that the sensor is in proper working order, that period varying randomly. The control unit is provided with a memory and stores responses to the random signals, and at intervals long with respect to the random periods, samples the memory. The control unit responds to the absense of a stored response from the transmissions of the sensor.

In a preferred construction, a plurality of sensors are employed with a single control unit, each of the sensors radiating a unique encoded signal. The control unit may thus determine by sampling which of the sensors has failed to radiate a signal received by the control unit during the sampling interval of the control unit.

Security system with radio frequency coupled remote sensors
Application Number
Publication Number
Application Date
November 12, 1981
Publication Date
July 24, 1984
Larry G Stolarczyk
Burmeister York Palmatier Hamby & Jones
A R F Products
G08B 29/00
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