Passive intrusion detection system

摘要

An intrusion detection system. An RF energy source transmits energy into a transmission cable that has a characteristic impedance subject to change by deformation of the cable. The cable is buried along a path that corresponds to a perimeter to be monitored. When an intruder places weight in the vicinity of the cable, the cable deforms and changes its characteristic impedance. Consequently a portion of energy transmitted into the cable reflects back where time-domain or frequency-domain reflectometry apparatus uses the reflected energy to identify the location of the intrusion along the cable and provide other characteristics of the intruder.