宽波束多子阵合成孔径声呐非线性CS算法

摘要

现有的多子阵合成孔径声呐成像算法大都是基于等效相位中心近似思想,在成像中通常忽略非"停-走-停"和方位向空变的影响,这在宽波束条件下会导致图像散焦.提出了一种兼顾成像精度和实现效率的宽波束多子阵合成孔径声呐非线性CS成像算法.利用泰勒展开的方法推导了回波信号相位的高阶项,进一步提高了相位补偿精度,并在高阶相位补偿中提出将调频率近似为随时延差量一阶线性变化和二阶非线性变化关系式的方法,充分考虑了PCA方位向的空变性对图像聚焦的影响.仿真实验结果表明,新算法比传统算法具有更好的成像聚焦质量,可以很好满足宽波束多子阵合成孔径声呐成像的需求.%The imaging algorithms of multiple-receiver SAS are almost based on the displace phase center approximation, and the method had always ignored the influence of nonstop-hop-stop and azimuth spatial variation approximation, it would result in the blurred image under the condition of wide-beam.An improved nonlinear Chirp Scaling algorithm (NCS) that has imaging accuracy and high efficiency is proposed in this paper.The high order terms of echo signal phase are derived by taylor expansion method, and the approach could improve the phase compensation accuracy.The modulation frequency is approximated by the first order linear variation and the second order nonlinear variation of the time delay difference in consideration of the influence of the azimuth spatial variation of PCA on imaging focus.The simulation conclusion showed that the new algorithm had better imaging quality as compared with the traditional algorithm, and it could satisfy the need of the wide-beam multiple-receiver SAS imaging.