Measurements of acoustic backscatter at shallow grazing angles at low kHz frequencies

Abstract

The acoustic backscattering strength of the seabed has been demonstrated to be one of the key inputs required in sonar performance prediction models. Yet, direct measurement of acoustic scattering from the seabed at shallow grazing angles presents a considerable challenge in littoral waters. The DRDC Atlantic (formerly DREA) Wide Band Sonar system, which consists of a parametric transmitter and a superdirective receiver, is ideally suited to make this measurement. The system was used to measure backscatter as a function of grazing angle and azimuth on the Scotian Shelf off the coast of Nova Scotia and on the Strataform site off the coast of New Jersey. Interpretation of the data set is enhanced with swath bathymetry measurements made at one of the experimental sites. In this paper the experimental geometry is described and the backscatter measurements are presented and discussed in light of the swath bathymetry results.