Title: Four wire multi-satellite intrusion alarm control system with tamper switch

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Abstract: An intrusion alarm system has a number of satellites each connected to a master by an unshielded cable having only four conductors, namely two power conductors, a drive signal conductor which supplies drive to the satellite transmitter and the satellite control circuit, and an alarm conductor. When an intrusion is detected by a satellite, its control circuit transmits a high level alarm signal on the alarm conductor to the master and also enables, but does not operate, a speaker in the satellite. The master has a rocker switch which an investigator turns off when he arrives at the supervised premises. This turns off the drive signal to the satellite. The control circuit of the satellite that caused the alarm responds by sounding its speaker, enabling determination of where the alarm occurred. The rocker switch may also be placed in a walk test position, enabling the system to be walk tested, and then may be returned to its initial supervisory position applying a reset signal to restore the satellite control circuits all to their normal supervisory condition. A tamper switch operates if a satellite is tampered with and causes transmission of a high level tamper alarm signal, different from the intrusion alarm signal, to the master.


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