Determination of the Time of Energy Return from Beamformed Data
NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
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Multibeam bathymetric sonar systems such as the Sonar Array Survey System SASS, the Sea Beam, and the Sea Beam 2000, are capable of collecting data which, after proper processing, may be used to map the bottom of the ocean. The sonar energy from the projector array impinges the ocean bottom as a narrow swath perpendicular to the ships heading. The echo from this swath is received by an array of hydrophones mounted athwartships. Beanforming permits good reception of energy propagating in a certain direction while attenuating energy propagating in other directions, and may be performed in hardware or software. Beamformed data gives a time history of the energy received from each look direction phi sub k. This data must be further processed to determine the time corresponding to the center of the beam, t sub c. The peak of the envelope corresponds to the intersection of the Maximum Response Axis MRA of the beam and the area ensonified. Once the time t sub c, has been determined, the bathymetry of the area surveyed can be obtained.
- Physical and Dynamic Oceanography
- Acoustic Detection and Detectors