联合等效斜距模型和自聚焦的地面动目标成像  

Joint equivalent slant range model and autofocus for ground moving target imaging

作　　者：闫莉[1] 张杰[2] 王家东[1] YAN Li;ZHANG Jie;WANG Jiadong(Academy of Advanced Interdisciplinary Research,Xidian University,Xi’an 710071,China;School of Electronic Engineering,Xidian University,Xi’an 710071,China)

机构地区：[1]西安电子科技大学前沿交叉研究院,西安710071 [2]西安电子科技大学电子工程学院,西安710071

出　　处：《航空学报》2024年第S1期75-90,共16页Acta Aeronautica et Astronautica Sinica

基　　金：国家自然科学基金(62301391,62101396,62171337,62201434)

摘　　要：针对目标的平移运动导致合成孔径雷达(SAR)成像结果散焦的问题,提出一种对散焦图像后处理的重聚焦算法。首先,针对目标斜距泰勒展开系数随目标方位空变,导致方位移不变性不再成立的问题,提出了一种系数非空变的等效斜距模型,同时,此斜距模型减小了斜视成像下时域距离走动校正引起的方位空变相位误差。其次,针对多普勒模糊导致的频域补偿函数失配、不同SAR算法结果中残余相位形式不同的问题,采用频域截取和逆匹配方法,得到了多普勒中心校正后的等效回波数据。最后,通过最小熵自聚焦方法对残余相位进行估计和补偿,从而得到聚焦图像。仿真实验验证了所提算法的有效性。A refocusing algorithm for post-processing defocused images is proposed to address the problem of defo⁃cusing in Synthetic Aperture Radar(SAR)imaging results caused by translational motion of the target.Firstly,in re⁃sponse to the problem that the spatial variation of the Taylor expansion coefficient of the target’s slant range spatially with the target’s azimuth will result in the loss of azimuth invariance,an equivalent slant range model with non spatially varying coefficients is proposed.This slant range model can weaken the phase error caused by time domain range walk correction in squint imaging.Secondly,to address the mismatch of frequency domain compensation function caused by Doppler ambiguity and the different residual phase forms in different SAR algorithm results,the frequency domain truncation and inverse matching methods are used to obtain the equivalent echo data after Doppler center cor⁃rection.Finally,the residual phase is estimated and compensated using the minimum entropy autofocus method,re⁃sulting in a focused image.The effectiveness of the proposed algorithm is verified through simulation experiments.

关 键 词：合成孔径雷达 地面运动目标成像 重聚焦 斜距模型 自聚焦 

分 类 号：TN957.52[电子电信—信号与信息处理]