Although SAR systems have been in use for some time, the acoustic equivalent, SAS, is still in its infancy. The problems associated with the slow speed of propagation relative to the forward motion of the sonar platform means the aperture is usually undersampled especially if only one physical antenna is used. To increase the aperture sampling rate, multiple hydrophones are deployed in a supposedly linear array. However sway and yaw in the sonar platform are inevitable, producing errors in the reconstructed image.

There appear to be several parallels with the problem of positional errors in two dimensional radio astronomy arrays and it may be that some autofocussing techniques originally developed for radio astronomy may have some cross-over applications.