INTRUSION DETECTION APPARATUS

摘要

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 selectabl e. Each is respectively responsive to sensed movement in cluding vibrations within the associated selected passband. An output affirmative si gnal is generated if the amplitude of the input signal c onstituent within the associated frequency range exceeds a threshold level for a predet ermined period of time. A logic circuit receives the ou tputs of all of the signal processors and provides an output alarm signal when a p redetermined combination of affirmative signals is recei ved from the signal processors. Such logic circuit preferably works with digita l signals obtained by analog-to-digital conversion. A t hreshold bias adjustment may be provided for adjusting the threshold amplitude of at least one input signal so that ambient noise may be take n into consideration by the logic circuit.