Intrusion detectors, and related systems and methods

Abstract

In at least one embodiment, a fence disturbance sensor is disclosed wherein a sensor cable having a signal processor on each end of the cable correlates the response data as seen from both ends of the cable to detect and locate intruders attempting to breach the fence. The processors at each end of the cable time multiplex the transmission of a phase coherent coded pulse sequence along the coaxial line creating both co-directional and contra-directional signals to propagate along the shielded moving-wire transmission line. When the cable is disturbed, the impedance of the shielded moving-wire transmission line, causing a change in the coupled signals which are used to detect and locate the disturbance. Hence when the cable is disturbed time multiplexed contra-directionally coupled responses are detected in complementary range bins where the amplitude and phase of the two responses are correlated by taking the complex product of the complementary range bin responses, thereby detecting the audio signal creating a magnitude and phase response in the array of complementary range bins. Hence to create an Event, a disturbance must be detected at the same time at the same location and with the same audio. When a prescribed number of Events occur at the same location within a prescribed time window an Alarm is declared.