A short history of synthetic aperture sonar

The fundamental theory that underpins any synthetic aperture sonar (SAS) is the same as that developed for synthetic aperture radar (SAR). However, the slow speed of propagation and higher attenuation of acoustic waves in water provides for some significant practical differences. The most important of these differences is that the aperture is often undersampled giving rise to grating-lobe artifacts in the image. Also since the aperture takes some time to traverse, motion compensation and medium turbulence have a significant effect. This paper highlights some key advances in SAS