Buried target detection with a synthetic aperture sonar

Abstract

Synthetic aperture sonar (SAS) systems can provide the high resolution and high signal-to-noise ratios that are important in detecting buried targets. Previous experiments with the Coastal Systems Station SAS have shown good results for above critical grazing angle targets and mixed results for below critical angle targets. Interest in characterizing the environmental conditions, which can allow detection at sub-critical angles, has prompted additional SAS testing. This paper describes a buried target experiment that included two 1.5-meter by 0.5-meter cylindrical targets, one 35-cm silicon-fluid-filled sphere, and two 58-cm air-filled spheres. These targets were buried under sandy sediment in 17 meters of water approximately 1 mile offshore from Panama City Beach, Florida. Above critical angle and below critical angle runs were made during November 2001 and June 2002. Environmental conditions and the seafloor ripple structure were reported by divers and, during the 2002 experiment, measured by the Applied Physics Laboratory/University of Washington with their second-generation in situ measurement of porosity (IMP2) instrumentation.