Accession Number : ADD012695

Title :   Seismic-Acoustic Low-Flying Aircraft Detector.

Descriptive Note : Patent,

Corporate Author : DEPARTMENT OF THE AIR FORCE WASHINGTON DC

Personal Author(s) : Fogler,Robert J

Report Date : 16 Dec 1986

Pagination or Media Count : 10

Abstract : The detection of low-flying aircraft is accomplished using both a microphone and geophone as sensors and signal system for measuring the correlation between the seismic ad acoustic signals. The signal processing system contains two amplication and band-limiting circuits, a delay circuit, an adaptive noise cancelling circuit, two signal smoothing circuits and a comparison circuit. The two amplification and bandlimiting circuits enhance a selected portion of the seismic and acoustic signals received by the sensors. The optional delay circuit is applied to the input acoustic signal, allowing the user the option of sensing or rejecting the detection of jet aircraft. The adaptive noise cancelling circuit generates an error signal by subtracting the signal components which are correlated between the seismic and acoustic signals from the input seismic signal.

Descriptors :   *PATENTS, *ACOUSTIC SIGNALS, *ADAPTIVE SYSTEMS, *DETECTORS, *ADAPTIVE SYSTEMS, *JET AIRCRAFT, *SIGNAL PROCESSING, CANCELLATION, CIRCUITS, NOISE, DELAY CIRCUITS, AIRCRAFT, DETECTION, LOW ALTITUDE, ACOUSTIC SIGNALS, INPUT, SIGNALS, COMPARISON, ERRORS, MICROPHONES, AMPLIFICATION

Subject Categories : Acoustic Detection and Detectors
      Seismic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE