基于FrFT与Kalman滤波的机动目标序列ISAR成像算法  

A Novel Sequential ISAR Imaging Algorithm for Maneuvering Target based on Kalman Filter Integrated with FrFT

作　　者：陈思言 张云华 杨杰芳 董晓 Siyan CHEN;Yunhua ZHANG;Jiefang YANG;Xiao DONG(The Department of Space Microwave Remote Sensing System,Aerospace Information Research Institute,Chinese Academy of Sciences,Beijing 10094,China;CAS Key Laboratory of Microwave Remote Sensing,National Space Science Center,Beijing 100190,China;School of Electronic,Electrical and Communication Engineering,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院空天信息创新研究院航天微波遥感系统部,北京100094 [2]中国科学院国家空间科学中心中国科学院微波遥感技术重点实验室,北京100190 [3]中国科学院大学电子电气与通信工程学院,北京100049

出　　处：《遥感技术与应用》2024年第5期1196-1204,共9页Remote Sensing Technology and Application

基　　金：国家自然科学基金项目(61971402)。

摘　　要：序列逆合成孔径雷达(Inverse Synthetic Aperture Radar,ISAR)指雷达对目标在较长一段时间内连续观测,近实时生成目标的ISAR图像序列。通过这些图像序列能够充分提取目标的散射信息和运动状态变化信息,对目标监测、跟踪和识别有很大帮助。研究充分利用相邻帧间目标运动的连续性,联合分数阶傅里叶变换(Fractional Fourier Transform,FrFT)和卡尔曼(Kalman)滤波技术,提出一种新的机动目标序列ISAR成像算法。该算法对方位向信号进行FrFT,通过搜索FrFT最佳能量聚集对应旋转角实现对方位向信号调频率(Azimuthal Chirp Rate,ACR)的测量,然后使用Kalman滤波技术得到ACR的最优估计值,实现对方位向信号精确的相位补偿。基于当前帧Kalman滤波得到的ACR最优估计值可以减小下一帧FrFT旋转角的搜索范围,提高计算效率。通过实测数据验证了该算法的有效性。相比常用的FrFT参数估计算法和PGA算法,该算法在成像质量和计算效率上均展现了优势。Sequential Inverse Synthetic Aperture Radar(ISAR)refers to that the radar continuously observing a non-cooperative maneuvering targets during a long period and generating a sequence of ISAR images nearly real time.According to these image sequences,the scattering information and motion state change information of the target can be fully extracted,which is very helpful for target monitoring,tracking and identification.Sequential ISAR imaging of maneuvering targets often requires fine phase compensation.Using the classical algorithm to compensate the phase for each frame individually is computationally intensive and takes a long time to process.In practice,the interval between two adjacent frames of the sequential ISAR is short and the change of the target's motion state is small.In this paper,a new algorithm for sequential ISAR imaging of maneuvering targets is proposed by making full use of the continuity of target motion between adjacent frames and combining Fractional Fourier Transform(FrFT)and Kalman filtering techniques.The algorithm performed FrFT on the azimuthal signal,and achieved the measurement of Azimuthal Chirp Rate(ACR)by searching for the best energy aggregation of FrFT corresponding to the rotation angle.The optimal estimate of the ACR is then obtained using Kalman filtering to achieve accurate phase compensation of the azimuthal signal.The optimal estimate of ACR based on the Kalman filtering of the current frame can reduce the search range of the FrFT rotation angle in the next frame and improve the computational efficiency.The effectiveness of the proposed algorithm is verified by real radar experiment.Compared with the classical FrFT parameter estimation algorithm and PGA algorithm,the proposed algorithm has excellent efficiency and can realize sequential ISAR imaging with better focusing effect.

关 键 词：逆合成孔径雷达 卡尔曼滤波 分数阶傅里叶变换 

分 类 号：TN957.52[电子电信—信号与信息处理]