Investigating layover effects in cross-correlation based interferometry for synthetic aperture sonar

For a synthetic aperture sonar (SAS) system with two receivers displaced by a vertical baseline, interferometric processing using cross-correlation can estimate the direction of arrival and thereby the topography. The cross-correlation peak position and value are utilized for time-delay and coherence estimates. In scenes with topography which causes layover, signal interference occurs. We show examples of when more information can be extracted from the crosscorrelation function in layover regions in order to detect and measure discrepancies, both in simulations and real sonar data collected by a HUGIN autonomous underwater vehicle carrying a wideband interferometric SAS.