A study of enhanced signal processing on multibeam bathymetric data

Due to budget constraints, many multibeam sonar customers are being required to operate smaller ocean survey vessels, equipped with less-expensive oceanographic tools. At the same time, ocean survey mission requirements are becoming more and more demanding. In response to this dilemma, L-3 SeaBeam Instruments, Inc. of East Walpole, MA has developed an innovative method for mathematically extending the performance of smaller, low-cost multibeam systems. This enhanced signal processing technique uses array extrapolation (AE) to provide: narrower receive beam dimensions; better separation of closely spaced targets; improved signal-to-noise performance. This paper studies the effectiveness of this technique as employed in an actual SEA BEAM 2112 multibeam sonar system by comparing several bathymetric data sets, acquired during survey, with and without AE being implemented. After processing the data, an examination is made of the beampatterns, the standard deviations obtained after detrending the data, and the maps produced from the bathymetric data. In conclusion, it is found that the AE technique does improve the results in most situations encountered in practice, and does not degrade sonar performance in the remaining situations