Performance of angle estimation methods applied to multibeam swath bathymetry

The performance is assessed of standard angle estimation methods applied to the evaluation of the direction of arrival of the seafloor returns, in the context of multibeam swath bathymetry. It is shown to be limited not only by the electronic or ambient noise on the hydrophones, but also by two noise contributions which result from the angular extent of the resolution cell on the seafloor and the frequency spread of the transmitted signal. This performance is computed for the phase interferometry, amplitude comparison and maximum amplitude direction estimators, from Monte-Carlo simulations in which the sea-bottom is modelled as a collection of independent, Rayleigh-fluctuating scatterers