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Synthetic-aperture sonar
Form of sonar using post-processing of sonar data / From Wikipedia, the free encyclopedia
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Synthetic-aperture sonar (SAS) is a form of sonar in which sophisticated post-processing of sonar data is used in ways closely analogous to synthetic-aperture radar.
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Synthetic-aperture sonars combine a number of acoustic pings to form an image with much higher along-track resolution than conventional sonars. The along-track resolution can approach half the length of one sonar element, though is downward limited by 1/4 wavelength.[1]
The principle of synthetic-aperture sonar is to move the sonar while illuminating the same spot on the sea floor with several pings. When moving along a straight line, those pings that have the image position within the beamwidth constitute the synthetic array. By coherent reorganization of the data from all the pings, a synthetic-aperture image is produced with improved along-track resolution. In contrast to conventional side-scan sonar (SSS), SAS processing provides range-independent along-track resolution. At maximum range the resolution can be magnitudes better than that of side-scan sonars.[2]
A 2013 technology review[3] with examples and future trends is also available. For academics, the IEEE Journal of Oceanic Engineering article: Synthetic Aperture Sonar, A Review of Current Status[4] gives an overview of the history and an extensive list of references for the community achievements up to 2009.
The length of the synthetic aperture is
Where R is the range, is the wavelength at center frequency and d is the along-track element size in the array.
is a programmable parameter which controls the process beamwidth - the beamwidth actually processed.[1]