Sonar imaging with the synthetic aperture technique

It is well known that the coherency content of acoustic signals propagated in the ocean has been exploited in signal processing schemes to enhance the signal-to-noise performance of sonar systems. Currently, acoustic imaging techniques which rely on coherency are being developed. Recently, some of these techniques have passed from laboratory curiosities to hardware systems. Two such applications are acoustic holography and synthetic aperture sonar (SAS). This paper reviews the basic principles of the SAS technique. The characteristics which are useful for some present day problems will be discussed. Limitations of the SAS method caused by the ocean environment will be noted in general terms.