Detection of Short-Tethered Objects with Interferometric Synthetic Aperture Sonar

This paper shows that conventional streaming processing of synthetic aperture sonar imagery and bathymetry data can cause performance limitations in the detection of tethered objects. This is particularly the case for wide-beam systems as the shadow response is markedly degraded compared to traditional side-scan sonar imagery. Also, standard unwrapping methods for correlation phase are not suited for height estimation of tethered objects. Alternative processing methods based on interferometry and multi-aspect imagery are proposed and demonstrated on sensor data from Kongsberg Maritime´s HISAS prototype processed with FFI´s FOCUS toolbox.