基于改进DPC近似的多子阵SAS距离多普勒算法

Effective range Doppler algorithm for focusing the multiple-receiver SAS data based on the modified DPC approximation

传统修正的偏置相位中心近似方法往往忽略距离历程近似误差的方位空变性,使得基于该方法的成像算法重建的图像出现近距离散焦和方位向偏移现象。为解决该问题,该文对修正的偏置相位中心近似方法进行改进,将双根号形式距离历程表示为类收发合置项、距离空变项和方位空变项之和的形式,有效提高了距离历程的近似精度;在利用驻定相位原理求取方位向驻定相位点的过程中,通过充分考虑距离历程方位空变性的影响,推导了更为精确的方位向驻定相位点,有效提高了点目标响应二维谱的准确性。在此基础上,提出一种适用于高分辨多子阵合成孔径声呐成像的距离多普勒算法,仿真试验和实测数据成像结果验证了该算法的有效性。

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 monosta- tic term, a range-variant term and an azimuth-variant term. By considering the azimuth-variant terra in deriving the azimuth phase stationary point using the principle d 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 syn- thetic aperture sonar （SAS）. The results of simulation and real data imaging show the effectiveness of the pro- posed algorithm.