Micro-steered multilooking in synthetic aperture sonar imaging

Inhalt:
The presence of speckle noise degrades synthetic aperture sonar (SAS) images. In this work we study despeckling based on incoherent averaging of several acquisitions of the same imaged area in combination with an adaptive micro-steering of the effective aperture and frequency response. The different acquisitions are formed by weighting the wavenumber spectrum of the image. The adaptive steering mitigate structural changes in the image like filling of shadow areas and smearing of point-like targets. The approach is demonstrated on real data from the HISAS interferometric SAS collected by a HUGIN autonomous underwater vehicle.