Accession Number : ADD017828

Title :   Sonar and Calibration Utilizing Non-Linear Acoustic Reradiation.

Descriptive Note : Patent, Filed 14 Mar 94, patented 5 Dec 95,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Konrad, William L

Report Date : 05 Dec 1995

Pagination or Media Count : 6

Abstract : An acoustic beam having at least one preset frequency is generated and directed towards a preselected non-linear acoustic reradiator. The reradiator returns acoustic waves having a different frequency. These reradiated waves are monitored, and a preselected parameter is detected in response to the returned reradiated acoustic waves. In a first embodiment, the preset frequency acoustic beam is generated at one or more frequencies and radiated by at least one projector. Upon incidence of the preset frequency acoustic beam, a preselected reradiator generates acoustic waves having a different frequency. The reradiated acoustic waves are used to calibrate a hydrophone. The reradiated acoustic waves can be controlled by the acoustic projector without a wire link. In another embodiment, the non-linear reradiation is caused by the action of a projected beam on cavitation generated by a vessel remote from the projector. The action of the acoustic beam upon cavitation at the propeller or other structure generates acoustic waves having a different frequency. Undesfrable reverberation is largely avoided since the receiver is adjusted to receive only the new frequencies generated by the cavitation. (MM)

Descriptors :   *ACOUSTIC WAVES, *HYDROPHONES, *SONAR, *PATENTS, *ACOUSTIC BEAMS, FREQUENCY, NONLINEAR SYSTEMS, CALIBRATION, REVERBERATION, MARINE PROPELLERS, SONAR PROJECTORS, CAVITATION

Subject Categories : Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE