Synthetic aperture sonar

Principle of synthetic aperture sonar

The principle of synthetic aperture sonar (SAS) is to combine successive pings coherently along a known track, in order to increase the azimuth (along-track) resolution. Ideally, the synthetic array length increases with range, such that the along-track resolution becomes independent of frequency and range. SAS technology has potential to image the seafloor with centimetre resolution up to hundreds of meters range.

Relevant links:  SAS at FFI, SAS at Kongsberg Maritime

See also the excellent Wikipedia on Sonar and SAR.