Fast Fourier techniques for SAS imagery

Fast block-processing Fourier techniques were originally developed for satellite-borne synthetic aperture radars (SAR) employing a colocated single transmitter/single receiver geometry. In contrast, almost all synthetic aperture sonars (SAS) now have a single transmitter/multiple receiver geometry and so some preprocessing is required to coerce the data into a single receiver format. If this is not done carefully, much of the inherent efficiencies of the Fourier-based block-processing is lost. Additionally there is the preprocessing required to achieve motion compensation as well as the phase center approximations required to correct for the underlying bistatic nature of the collected data.