一种适用于机载/固定站构型BiSAR成像的改进相位梯度自聚焦方法  

A Modified Phase Gradient Autofocus (PGA) Algorithm for Airborne/Stationary Bistatic SAR Imaging

作　　者：周松[1] 包敏[2] 陈士超[1] 邢孟道[1] 保铮[1] 

机构地区：[1]西安电子科技大学雷达信号处理国家重点实验室,西安710071 [2]西安电子科技大学电子工程学院,西安710071

出　　处：《电子与信息学报》2013年第6期1456-1463,共8页Journal of Electronics & Information Technology

基　　金：国家自然科学基金(61201284;61001211);航空基金(20110181004)资助课题

摘　　要：在机载/固定站构型双站合成孔径雷达(Airborne/Stationary Bistatic Synthetic Aperture Radar,A/S-BiSAR)成像中,回波信号方位不变性的假设不再成立;完成距离徙动校正和距离压缩之后,同一距离单元处信号的多普勒调频率具有沿方位向变化的特性。该信号特性导致了传统的相位梯度自聚焦(Phase Gradient Autofocus,PGA)方法对相位误差的估计精度显著下降。针对该问题,该文提出了一种改进PGA方法。与传统PGA方法相比,该方法通过增加对样本信号的剩余二次相位补偿,有效减小了变化的多普勒调频率对相位误差估计的影响,从而提高了对相位误差的提取精度;此外,该方法考虑了对距离空变相位误差的估计和补偿,使之适用于宽测绘带条件下的A/S-BiSAR成像。实测数据的处理和分析验证了该文方法的有效性。In Airborne/Stationary Bistatic Synthetic Aperture Radar （A/S-BiSAR）, the assumption of translational invariance is no longer available. After the Range Cell Migration Correction （RCMC）, the range compressed signal in the same range gate exhibits azimuth-variant Doppler rates which make the phase error difficult to be estimated from the echoes by using the available Phase Gradient Autofocus （PGA） algorithms. To deal with this problem, a modified PGA algorithm is proposed. Comparing with the traditional PGA, the Residual Quadratic Phase （RQP） caused by the azimuth-variant Doppler rates is additionally estimated and compensated. As the influence of the azimuth-variant Doppler rates is greatly reduced, a phase gradient estimator is subsequently applied to accurate phase error retrieval. Furthermore, the range-variance of the phase error is also concerned in the phase error estimation and correction, thus the proposed algorithm is suitable for A/S-BiSAR with wide swath in range. Raw data experiments are presented to verify the advantages of the proposed algorithm.

关 键 词：双站合成孔径雷达(BiSAR) 机载 固定站构型 剩余二次相位 相位梯度自聚焦(PGA) 

分 类 号：TN959.73[电子电信—信号与信息处理]