Abstract: A system is provided for detecting the presence of two or more acoustic sources or targets such as vehicles that are traveling between an array of unattended passive ground sensors, in which the sensors each include a phased-array microphone and processing to determine the bearing to the acoustic target. The bearings from pairs of these sensors are subtracted one from the other to provide a bearing line difference “delta” which is the indicator of the presence of an acoustic target close to the line between the two sensors of the pair. A tripwire threshold indicating the presence of a target is set when the absolute value of this bearing line difference “delta” is greater than, for instance, 150°, with the “delta” being 180° when the target is on the line between the two sensors.

Abstract: A system is provided for detecting the presence of two or more acoustic sources or targets such as vehicles that are traveling between an array of unattended passive ground sensors, in which the sensors each include a phased-array microphone and processing to determine the bearing to the acoustic target. The bearings from pairs of these sensors are subtracted one from the other to provide a bearing line difference “delta” which is the indicator of the presence of an acoustic target close to the line between the two sensors of the pair. A tripwire threshold indicating the presence of a target is set when the absolute value of this bearing line difference “delta” is greater than, for instance, 150°, with the “delta” being 180° when the target is on the line between the two sensors.