一种稳健的频率步进SAR距离向栅瓣抑制方法  

A Robust Method for Range Grating Lobe Suppression in Stepped Frequency SAR

作　　者：高文斌 GAO Wenbin(Department of Electronic and Communication Engineering,Beijing Electronic Science&Technology Institute,Beijing100070,China)

机构地区：[1]北京电子科技学院电子与通信工程系,北京100070

出　　处：《计算机科学》2024年第8期209-216,共8页Computer Science

基　　金：中央高校基本科研业务费课题(328202207)。

摘　　要：频率步进合成孔径雷达(Synthetic Aperture Radar,SAR)的系统传递函数中存在幅度和相位误差(Magnitude Error and Phase Error,MEPE),通过宽带合成操作在距离宽带信号中引入了周期性MEPE,从而导致宽带合成后的高分辨率距离像(HRRP)中出现周期性栅瓣。经过后续SAR成像处理,这些周期性栅瓣在图像中表现为虚假目标,严重影响SAR图像目标的检测与识别。为此,基于SAR图像的栅瓣抑制(Grating Lobe Suppression,GLS)算法被提出,其基于点状目标假设,利用SAR图像中的强点目标实现图像栅瓣的有效抑制。然而,对于非点状目标场景,已有基于SAR图像的GLS算法的性能显著下降,而且会引起图像散焦。因此,文中提出了一种基于目标信息差异的GLS算法,取名为目标信息差异法。该算法不基于点状目标假设,通过估计宽带合成后的理想HRRP与实际HRRP之间的信息差异,稳健地估计出合成宽带信号中的周期性MEPE。通过补偿该周期性MEPE,该算法可以将频率步进SAR距离向栅瓣抑制到图像的背景水平。通过对不同GLS算法进行性能对比发现,所提GLS算法受图像信杂比影响小,且同时适用于非点状目标和点状目标场景,相比已有GLS算法具有明显的优势。实测数据处理结果证明了所提方法的有效性和相对已有GLS算法的优越性。The magnitude error and phase error(MEPE)in the system transfer function of the stepped-frequency synthetic aperture radar(SAR)introduces periodic MEPE in the synthesized wideband signal,resulting in periodic grating lobes in the high-re-solution range profile(HRRP).After subsequent SAR imaging processing,these periodic grating lobes appear as false targets in the SAR image,seriously affecting SAR image target detection and recognition.Therefore,the GLS algorithm based on SAR images has been proposed,which is based on the assumption of point targets and effectively suppresses image grating lobes by utilizing strong point targets in SAR images.However,for non-point target scenes,existing GLS algorithms based on SAR images can cause image defocusing while suppressing image grating lobes.Therefore,this paper proposes a GLS algorithm based on target information differences,named the target information difference method,which is not based on the assumption of point-shaped targets.By estimating the information difference between the ideal HRRP and the actual HRRP of the target after wideband synthesis,it can robustly estimate the periodic MEPE in the synthesized wideband signal.By compensating for this periodic MEPE,the algorithm can suppress the range grating lobes to the SAR image background level.By comparing the performance of different GLS algorithms,it is found that the proposed GLS algorithmis less affected by the image signal-to-noise ratio and is suitable for both non-point target and point target scenes,thus having obvious advantages comparing to existing GLS algorithms.Experimental data processing results demonstrate the effectiveness and superiority of the proposed method compared to existing GLS algorithms.

关 键 词：栅瓣图像 频率步进合成孔径雷达 背景水平 宽带信号 图像散焦 

分 类 号：TP751[自动化与计算机技术—检测技术与自动化装置]