Bearing Estimation Uncertainties for the Volume Search Sonar

摘要

The Volume Search Sonar (VSS) uses a partial cylindrical array populated over a 286 deg sector to (1) transmit a stepped FM pulse over a 243 deg vertical fan beam centered on nadir and (2) receive with 27 fore-aft beam pairs steered symmetrically about a plane perpendicular to the axis of the cylinder. The bisectors of these beam pairs are spaced at 7.16 deg intervals around the cylinder. Up to 52 phasors are formed by conjugate products of adjacent beams across-track (26 phasors forward and 26 phasors aft). These phasors are further combined in groups of two phasors along-track, and two or three phasors across-track to obtain additional soundings between them. For swath bathymetry purposes, 123 of the 153 possible phasor combinations are retained to form three across-track bathymetry profiles per ping cycle in a swath angle of roughly +-73 deg about nadir. Each ping, a 3D patch of this swath is sampled and continuous bathymetry coverage is possible at survey speed of 25-30 knots. Seafloor acoustic backscatter imagery coregistered with the bathymetry is also obtained through this process, giving the VSS efficient reconnaissance seafloor mapping capabilities.