Patent ID: 6370083
Filing Date: 2002-04-09
Classification: G01V

Abstract:
An acoustic signal detection apparatus comprising:a plurality of acoustic signal detection channels, each of which having an input for receiving acoustic signals from a corresponding acoustic signal sensor and processing circuitry to provide a processed acoustic signal when an acoustic signal is detected, the processing circuitry including a filter circuit for removing from the received acoustic signal all frequencies above a predetermined frequency, the filter circuit having an output for outputting a filtered acoustic signal and a circuit for inverting the filtered acoustic signal, each acoustic signal detection channel further including a circuit for outputting a signal that represents the sum of then filtered acoustic signal and the inverted acoustic signal and which defines the processed acoustic signal; and a circuit for summing the processed acoustic signals outputted by the acoustic signal detection channels to form a single acoustic output signal and outputting the single acoustic output signal if at least one of the acoustic signal detection channels outputs a processed acoustic signal.