AQS-20 sonar processing enhancement for bathymetry estimation

Bathymetry is used to determine optimal tactics during Mine Warfare operations. Previous work demonstrated that bathymetric data could be acquired from the Volume Search Sonar (VSS) mounted on the AQS-20 system. The VSS transmitter produces a pulse at approximately one-second intervals along the track. The returning pulse from the sea-bottom is received by a group of sensors and beamformed in hardware into two fans (one pitched slightly forward and a second pitched slightly aft). A possible way to increase the accuracy of the bathymetry data is to improve the angle of arrival estimates by processing the adjacent across-track and/or along-track beam pairs. This paper employs narrow-beams monopulse techniques in order to investigate improvements to the bathymetric data over conventional processing. A comparative analysis of the experimental results for both the new and the classical technique is presented.