Abstract:
A system for remote sensing of ocean bathymetry using a forward-looking sonar is being developed. The system combines a wide-angle transmit beam (for full volume coverage) with multiple, steered, narrow receive beams for object localization. Sample bathymetry data were collected in Narragansett Bay, RI using a 10-ms-duration, 3-kHz bandwidth, linear stepped FM transmit sonar pulse, centered at 87 kHz. Bathymetry results compare favorably with a sidescan of the test area [M. R. Medeiros and R. N. Carpenter, Proc. IEEE AUV-96, pp. 185--191]. In addition to bathymetry the system returns an echo level map which can, after correcting for system gains, transmission loss, and grazing angle, provide a measure of bottom backscatter. The system is currently under investigation at the Naval Undersea Warfare Center, Division Newport, for use as a bottom detection and collision avoidance forward-looking sonar for unmanned underwater vehicles.