Abstract: An intrusion detection system for a space secured in part by a deflectable physical barrier includes a cable sensor mounted on the barrier in such manner that it stretches and flexes in response to deflection of the barrier, thereby to produce an output signal representing such movement. A signal processor receives the signal from the coaxial cable and provides an output affirmative signal if the amplitude of the cable signal, within a predetermined frequency range lying below about 30 Hz, exceeds a predetermined level for a predetermined time interval.

Abstract: Intrusion detection apparatus for use in perimeter security systems and the like is provided with multiple channel signal processing. Each signal processor includes a bandpass filter whose passband is selectable. Each is respectively responsive to sensed movement including vibrations within the associated selected passband. An output affirmative signal is generated if the amplitude of the input signal constituent within the associated frequency range exceeds a threshold level for a predetermined period of time. A logic circuit receives the outputs of all of the signal processors and provides an output alarm signal when a predetermined combination of affirmative signals is received from the signal processors. Such logic circuit preferably works with digital signals obtained by analog-to-digital conversion.

Abstract: A sensor post has a hollow interior and a semi-rigid surface which flexes in response to an applied force. Sensor bars are mounted to the semi-rigid surface in a cantilevered fashion, and include an intermediate electrically insulated section located inside the interior of the sensor post. The sensor element mounting means is rigidly mounted to a portion of the sensor post which remains essentially stationary during an intrusive event. Sensing elements are made of a flexible semi-conductive sensing material, whose resistance increases when the material is stretched, and are mounted so as to straddle an electrically insulated section of the sensor bars. A signal analysis means detects an increase in the resistance of the sensing elements and generates an alarm.

Abstract: In a taut wire type intrusion detection system, each parallel wire defining a section of security fence is tensioned between a pair of wire-supporting vertical anchor posts. Intermediate the anchor posts there is provided a row of regularly spaced vertical detector posts each presenting a plurality of individual sensors, each associated with one of the taut wires and operable to produce a sensor signal when the tension of the wires changes. With each detector post there is associated sensor signal processing means, operable to analyze the sensor signals produced by the sensors of the detector post in response to changes in tension of the taut wires, and to generate output signals correlatable with the sensor signals. Each sensor preferably includes a pressure transducer comprising a partially conductive compressible elastic sensing element whose resistance changes with applied pressure.