Showing papers on "Intrusion detection system published in 1984"

Passive infrared intrusion detection system

Abstract: A passive infrared intrusion detector has: a multi-faceted parabolic reflector for dividing a target controlled area into a plurality of optically divided detection zones, for collecting infrared rays emitted from an object within the controlled area; a passive infrared intrusion sensor combined with the reflector to detect the collected infrared rays; a first means for generating a pulse when an absolute value of an output of the passive intrusion sensor exceeds a reference value; and a second means for generating an alarm signal when predetermined pulses are received from the first means within a predetermined period. A pulse width discriminator is used to eliminate narrow noise pulses.

Intrusion detection system

Abstract: There is disclosed an intrusion detection system employing vibration sensors which are arranged in a series loop consisting of first and second wires and which loop is terminated by a terminating impedance. Coupled to the wires is a processing circuit which supplies a square wave biasing waveform for the loop and a DC voltage determined by the terminating impedance. By detecting the magnitude of the DC level, the processor can determine if the loop has been opened or shorted or if any one of the sensors in the loop has been activated due to an intrusion. Thus the system described employs two wires for supplying both power and sensing of output signals from the loop being monitored.