Abstract:

Because of ignoring the azimuth-variance of range history approximation error, the algorithm based on the conventional displacement phase center (DPC) approximation always suffers from some serious problems of azimuth migration and closer range defocusing. In order to solve these problems, a modified DPC approximation is proposed, which expresses the double-square-root form range history by the sum of a monostatic term, a range-variant term and an azimuth-variant term. By considering the azimuth-variant term in deriving the azimuth phase stationary point using the principle of stationary phase, a more accurate azimuth time phase stationary point is derived and the point target response two-dimensional spectrum is correspondingly improved. Based on that, a high resolution range Doppler algorithm is presented for the imaging of multiple-receiver synthetic aperture sonar （SAS）. The results of simulation and real data imaging show the effectiveness of the proposed algorithm.