Precision analysis of bathymetry measurements using phase difference

Many bathymetric sonar systems use nowadays the phase difference principle. Possible causes of degradation of these phase measurements are analysed. It is shown that under current conditions the effects of additive noise and baseline decorrelation are surpassed by the sliding footprint effect, bound to the geometrical configuration and the receiver spacing. This effect may be described analytically or checked from numerical simulations. It is shown to be specially prevalent for side-scan sonars with a vertical interferometer