Swath bathymetry and SAS autofocus using a Chirp source

Abstract

Swath bathymetry and SAS autofocus can both be treated as problems in correlating echoes from a scatterer distribution on the seabed. Using a chirp source, the phase derived from quadrature match-filtering can replace the narrowband phase in complex correlation operations. Pulse compression then enables bathymetry to be estimated more easily and accurately than with the corresponding narrowband processing. Using similar processing, the SAS auto-focus method gives direct estimates of unknown cross-track plafform displacement. Field experimental equipment for the Swedish project is briefly described.