Broadbeam multi-aspect synthetic aperture sonar

Broadband multi-aspect processing promises to Improve the image quality and target detection/classification capabilities of imaging systems since the different aspects or 'looks' can provide additional clues about the shape and dimension of targets. To obtain high cross-range resolutions, these different 'looks' can be obtained by steering the main beam of a synthesized aperture. Synthetic aperture beam steering can be performed on data that was collected in stripmap mode. Accurate beam steering requires correct data handling by the reconstruction algorithm since the target area is in the near-field of the aperture. The limits of steering are determined primarily by the beamwidth of the system in question. The low-frequency synthetic aperture sonar system in use at the Coastal Systems Station in Panama City, Florida is well suited to this type of beam steering because of its broad beams (100degrees for the receiver and 50degrees for the transmitter) and its spatially oversampled design. Results obtained from simulated point targets as well as real data are presented.