Acoustic Presence Detection Method and Apparatus.
DEPARTMENT OF THE NAVY WASHINGTON D C
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This patent describes a method and means for passively detecting presence of noise radiating devices in a noise environment by determining the number of times per time sample that a received noise signal upwardly crosses a preselected threshold level, comparing this number with the number of upward crossings caused by a standard noise signal or background noise signal, and applying a predetermined ratio criteria. The noise sensors in the detection system may comprise a directional acoustic transducer in combination with an omnidirectional acoustic transducer, and acoustic transducer in combination with an artificially generated noise signal, or a single acoustic transducer. Author
- Acoustic Detection and Detectors