Patent ID: 8195409
Filing Date: 2012-06-05
Classification: G01S,G01V

Abstract:
1. An intruder detection apparatus, comprising: a plurality of acoustic emission sensors arranged in a cluster beneath the surface of a body of water, the cluster defining a first pair and a second pair of acoustic emission sensors within the cluster; and a computing device configured to: receive a first signal produced by one acoustic emission sensor within the first pair, the first signal being produced in response to said one acoustic emission sensor detecting a first acoustic emission generated by and emanating from a source, receive a second signal produced by another acoustic emission sensor within the first pair, the second signal being produced in response to said another acoustic emission sensor detecting the first acoustic emission generated by and emanating from the source, and receive at least a third signal produced by one acoustic emission sensor within the second pair, the third signal being produced in response to said one acoustic emission sensor within the second pair detecting a second acoustic emission generated by and emanating from the source; determine a first cross-correlation factor between the first signal and the second signal, based on a time difference between the detection of the first acoustic emission by the acoustic emission detectors in the first pair; determine a second cross-correlation factor relating to at least the third signal and another signal from another acoustic emission sensor of the second pair, based on a time difference between the detection of the second acoustic emission by the acoustic emission sensors of the second pair; determine a bearing to the source based on at least one of the first cross correlation factor and the second cross correlation factor; and determine a range to the source based on at least one of the first correlation factor and the second correlation factor.