High-resolution interferometry for multibeam echosounders

Two main approaches are met today in swath bathymetry sonar systems. Interferometric sidescan sonars use the phase difference between two (or more) close receivers to estimate the arrival angle of instant signal. Multibeam echosounders (MBES) use beamforming methods (prior to amplitude or phase detection) in order to obtain an intrinsic spatial resolution and to improve the received signal to noise ratio (SNR). Here we present a comparison between the interferometry method and high-resolution techniques. Experimental results obtained from data recorded with a Simrad EM300 30-kHz multibeam echosounder are presented, showing that both methods provide a similar DOA estimation.