INTRUSION DETECTION SYSTEM

摘要

A microprocessor-based ultrasonic intrusion detection system includes an initialization mode wherein a plurality of echoes are cumulatively processed to produce a reference or signature data set representing the area to be monitored without intruding objects. Later received echoes are compared to this signature so that an intruding object will cause generation of an alarm signal. Time varying thresholds are utilized to compensate for attenuation caused by increased distance.