A Study On The Synthetic Aperture Sonar

Synthetic array sonar includes both synthetic aperture sonar (SAS) and inverse synthetic aperture sonar (ISAS). It is a novel kind of underwater imaging sonar. It is an important research field in underwater high technology and has a widely applying prospect. The very strong property of the synthetic array sonar is the ability to acquire a high azimuth resolution from a physically small array.The thesis reviews the theory that is the basis of synthetic aperture processing. Then the components of synthetic aperture sonar and parameter selecting are studied. Time-frequency analysis is introduced. After the model of maneuvering target is established, a new signal detection and estimation algorithm is introduced, which is based on the Radon-XWVD transform. The experiment validates that the performance of this new method can detect signal with very low SNR. Aimed on multi-target situation, utilizing the idea of eliminating one by one, the problem that the weak signal is covered up by robust signal cross term is resolved.The thesis also studies the theory of inverse synthetic aperture sonar imaging. Since the target moves irregularly, the Doppler effect of each scatter and the imaging projection change with time. The concept and algorithm of Range-Instantaneous Doppler imaging, based on WCWD, is presented. This algorithm is effective to the maneuvering target. At last the complexity and presupposition of the algorithm is discussed. The simulations concerned are also presented.