Focusing Multireceiver SAS Data Based on the Fourth-Order Legendre Expansion

Abstract

Using Legendre polynomials and the derivation method of the implicit function, this paper proposes a range-Doppler algorithm for multireceiver synthetic aperture sonar. Based on Legendre polynomials, the two-way slant range is first expanded into a power series with respect to the slow time. Then, the derivation method of the implicit function is exploited to deduce the point of stationary phase and point target reference spectrum (PTRS). Based on this PTRS, the paper presents an imaging algorithm, which uses the range-dependent sub-block processing method to cancel the space-variant coupling between the range and azimuth dimensions. Simulation results and real data processing are presented to validate the proposed method.