Accession Number : ADD016008

Title :   Preprocessor and Adaptive Beamformer for Linear-Frequency Modulation Active Signals.

Descriptive Note : Patent, Filed 6 Oct 92, patented 5 Oct 93,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Lockwood, James C

Report Date : 05 Oct 1993

Pagination or Media Count : 25

Abstract : A device is provided for processing an echo received by an array of N receiving elements from a target at range R ensonified by an LFM signal of bandwidth B transmitted for a duration T. The device receives each elements output f sub n(t) over the elements total receiving time and selects time window element outputs f sub n(t), which are discrete portions of f sub n(t), each time window extending from an arbitrary initial time T sub o to time T sub f and is spaced from. T sub o no more than T and, if there is a target within the window, an echo is received at time T sub n. Further the device produces element frequency difference outputs g sub n(t) from the frequency difference between a replica of at least a portion of the transmitted LFM signal and the time window, element outputs f sub n(t), the outputs g sub n(t) being tones with frequencies directly proportional to the time T sub n of the target from the time To so that the target range R=(c/2)(T sub o + T sub n)+delta R sub n, where c is the speed of sound, and delta R, is the distance by which R exceeds each element's range to the target.

Descriptors :   *ECHOES, *HYDROPHONES, *PATENTS, *BEAM FORMING, ARRAYS, BANDWIDTH, FREQUENCY, ACOUSTIC SIGNALS, SOUND, TARGETS, VELOCITY, SIGNAL PROCESSING, SIGNALS, ACOUSTIC ARRAYS, ACOUSTIC SCATTERING

Subject Categories : Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE