一种适用于星载大斜视聚束SAR的改进距离徙动算法  

Improved Range Migration Algorithm for High-Squint Spaceborne Spotlight SAR

作　　者：邓钱钰 王纪平 郭淑婷 杨果 刘衍琦 毛新华 DENG Qianyu;WANG Jiping;GUO Shuting;YANG Guo;LIU Yanqi M;AO Xinhua(Key Laboratory of Radar Imaging and Microwave Photonics,Ministry of Education,College of Electronic and Information Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing,Jiangsu 211106,China)

机构地区：[1]南京航空航天大学电子信息工程学院雷达成像与微波光子技术教育部重点实验室,江苏南京211106

出　　处：《信号处理》2024年第3期569-586,共18页Journal of Signal Processing

基　　金：国家自然科学基金(62071225);江苏省自然科学基金(BK20211181);航空科学基金(2020Z017052001)。

摘　　要：星载大斜视聚束合成孔径雷达(Synthetic Aperture Radar,SAR)探测范围大、目标驻留时间长,有广泛的应用前景,但会带来较大的距离徙动,使得回波信号耦合严重。传统算法使用固定窗接收数据,为了采集完整,则需要较大的采样窗,但采得数据中存在大量的无效数据,采样效率很低。为解决时域采样效率低等问题,可使用滑窗接收模式,但该模式一般结合时域算法或极坐标格式算法使用,而在星载SAR大场景成像的情况下,时域算法计算效率低下,极坐标格式算法的聚焦半径较小,因此本文提出了一种改进的距离徙动算法来解决大斜视滑窗接收模式下的高效精确成像问题。本文建立了滑窗接收模式下的时域回波模型,利用傅里叶变换的性质推导出精确两维解析频谱,并基于上述两维解析频谱,提出雷达视线坐标系下的两维空间域解耦方法并给出对应的完整成像处理流程,最后通过仿真实验验证算法的有效性。本文提出的新方法既能解决大斜视两维频谱扭曲带来的频域采样效率低下问题,又可避免传统方法在大斜视模式下的残留距离徙动放大问题,为后续的自聚焦处理提供便利。Spaceborne high-squint spotlight synthetic aperture radar(SAR)has wide application prospects because of its large detection range and long residence time.However,large range migration is produced,causing significant echo signal coupling.The traditional algorithm uses a fixed window to receive the data.For more complete data collection,a large sampling window is needed,but a lot of invalid data are also acquired,and the sampling efficiency is very low.To solve the problem of low sampling efficiency in the time domain,the sliding window receiving mode can be used.This mode is generally used in combination with the time domain algorithm or the Polar Format Algorithm.In the case ofspaceborne SAR imaging in large scenes,the time domain algorithm has low computational efficiency and the Polar Format Algorithm has a small focusing radius.Therefore,this paper proposes an improved Range Migration Algorithm to address the problem of efficient and accurate imaging in high-squint sliding window receiving mode.Accordingly,the time-domain echo model in sliding window receiving mode is established,and the accurate two-dimensional analytic spectrum is derived via Fourier transform.Based on the two-dimensional analytic spectrum,a two-dimensional spatial domain decoupling method in the radar line-of-sight coordinate system is proposed and the corresponding complete imaging processing flow is obtained.Finally,the effectiveness of the algorithm is verified through simulation experiments.The proposed method can not only solve the problem of low sampling efficiency caused by the distortion of the twodimensional spectrum of high squint,but also avoid the problem of residual distance migration amplification in the traditional method in the high squint mode,as well as provide convenience for the subsequent self-focusing processing.

关 键 词：大斜视 星载合成孔径雷达 距离徙动算法 滑窗接收 

分 类 号：TN959.7[电子电信—信号与信息处理]