超高分辨率机载合成孔径雷达空变运动补偿技术研究

Synthetic aperture radar(SAR) is an important tool for military reconnaissance and civil remote sensing. As an imaging radar, improving the imaging resolution is meaningful to target detection,identification, feature extraction and so on. Consequently,there is a growing demand for improving the SAR's resolution to centimeter level (which is ofen referred to as ultra-high resolution) in recent couple years. Although SAR technology has matured day by day, ultra-high resolution SAR imaging remains a great challenge not only for radar system, but also for signal processing.As far as the signal processing technique is concerned, accurate motion compensation will become an important guarantee for ultra-high resolution SAR imaging.In this program, we will study motion compensation techniques in three different SAR processing stages, i.e., before image formation, during image formation and after image formation. For motion compensation before image formation, we will study the compensation of radar motion from pulse to pulse in a pulse cluster for stepped-chirp radar. While for motion compensation during image formation, we will focus on the accurate space-variant compensation techniques when radar platform undergoes an arbitrary flight path. Finally, we will study motion compensation based on radar data, i.e., autofocus, which becomes a two-dimensional problem in ultra-high resolution SAR imaging. We will exploit the analytical relationship between residual range cell migration and azimuth phase error, and then estimate and correct the residual range cell migration by recurring to the azimuth phase error estimation.Our research results will provide theoretical support for the development of ultra-high resolution airborne SAR system.

合成孔径雷达（SAR）是军事侦察和民用遥感的重要手段，当前，将成像分辨率提高到厘米量级（超高分辨率）是SAR技术发展的一个重要方向。虽然中低分辨率SAR技术已日趋成熟，但超高分辨率成像无论对于雷达系统还是成像信号处理都仍然存在相当大的挑战。就成像信号处理而言，能否实现精确的全空变运动补偿将成为制约超高分辨率SAR聚焦成像的关键。本项目空变运动补偿研究拟围绕成像算法展开，具体研究成像前、成像过程中和成像处理后三个阶段的运动补偿。对于成像前的运动补偿，重点研究步进调频信号带宽合成时雷达运动效应的空变补偿；对于成像过程中的运动补偿，拟研究能够实现距离、方位和高度全空变的精确运动补偿方法，同时特别注意运动补偿与成像算法的有机结合；而对于成像处理后的运动补偿，重点在于研究具有同时校正方位相位误差和残留距离徙动能力的两维自聚焦方法。本项目研究成果将为研制超高分辨率机载SAR系统提供理论支撑和技术储备。

本项目针对超高分辨率机载SAR成像处理中面临的空变运动误差补偿难题展开研究,研究内容主要围绕成像算法展开，具体研究了成像前、成像过程中和成像处理后三个阶段的运动补偿。对于成像前的运动补偿，重点研究了步进调频信号带宽合成时雷达运动效应的空变补偿；对于成像过程中的运动补偿，研究了能够实现距离、方位和高度全空变的精确运动补偿方法，同时特别注意运动补偿与成像算法的有机结合；而对于成像处理后的运动补偿，重点研究了具有同时校正方位相位误差和残留距离徙动能力的两维自聚焦方法。通过该项研究,我们突破了制约超高分辨率机载SAR成像信号处理的若干关键技术难题,提出了精确高效的运动误差补偿方案,该补偿方案已在国内多个雷达主机所的多种国防重点型号中获得应用,通过国防科技成果鉴定被认定达到国际领先水平。