Seafloor scatter induced angle of arrival errors in swath bathymetry sidescan sonar

Swath bathymetry sidescan sonar obtains bathymetry information from seafloor returns by measuring the phase difference as a function of time between two closely-spaced, vertically separated sidescan transducers. In general, over a slowly varying seafloor, results compare favourably with depth measurements taken from larger more costly multibeam sounders and therefore the popularity of swath bathymetry has been increasing. However, susceptibility to spurious and nonstationary differential phase errors, known as `glint´, has slowed overall acceptance and prevented the development of robust bathymetric processing algorithms. The purpose of this paper is to investigate, in a deterministic sense, the mechanism by which glint is produced. The authors begin by introducing a z transform method for deterministic analysis of discrete scattering problems and then apply it to the differential phase measurements of swath bathymetry sidescan systems. A simple two point scattering model is then used to demonstrate the potential for significant angle of arrival errors in a typical swath bathymetry sidescan system