【作者】 刘阳；

【导师】 王国玉；

【作者基本信息】 国防科学技术大学 ， 信息与通信工程， 2012， 博士

【摘要】 合成孔径雷达（SAR）及其地面动目标检测（GMTI）日益成为战略侦察和战场监视系统的重要手段，对重要军事目标构成了严重威胁。针对SAR/GMTI的干扰技术已经成为电子对抗领域中的一个重要新课题。本文基于ISAR观测中的微多普勒现象，将其发展运用到SAR及GMTI的对抗领域中，基本形成了一套基于微动特性的新型SAR/GMTI干扰技术。论文首先指出了课题的研究背景及意义；介绍了SAR系统研究现状，归纳了SAR干扰技术和干扰效果评估技术的研究现状，重点分析了SAR干扰技术的类型、发展历程、发展趋势和存在的问题；阐述了本文的主要研究工作。论文根据微运动目标的观测矢量模型，以匀速圆周运动和简谐振动两类典型运动规律目标为研究对象，建立了这两者较以往研究更为精确的多普勒时频模型，并利用不同微运动的微多普勒差异，为SAR/ISAR目标识别提供了新的微多普勒特征。同时也根据SAR观测目标可能的几何条件，分析了微多普勒模型的简化条件，给出了其简化模型。论文从静止目标上单个微动散射点的基本模型入手，依次分析了物体整体平动、多个微动散射点以及微动幅度跨越多个距离单元等情况的成像特点。分析了由于微动目标与方位向实体目标之间多普勒历程的差异，所导致微动目标图像在距离徙动校正条件下的散焦情况，给出了良好聚焦的约束条件。利用某机载SAR的实测数据，得到了实际微动目标的成像结果，指出了利用无源微动目标进行干扰的可行性。最后以子孔径相关法自聚焦为实例，定性分析了微运动类型干扰对SAR自聚焦影响的可能。论文以3种成熟的多天线SAR/GMTI技术为实际研究对象，分析了微动目标的幅度和相位特性，指出了利用微动特性对GMTI实施干扰的可行性。论文还定性地分析了微动目标对FrFT动目标检测技术的影响。论文在以上研究成果基础上，提出了微运动类型SAR干扰方法。首先从功率上分析干扰的功率需求，总结了干扰参数的选择问题。以保护地面面目标需求出发，提出了一种基于距离向固定噪声样本的“方位相干噪声”干扰样式；并以距离向噪声调频干扰为例，分析了干扰效果。针对军事固定阵地的保护，提出了一种简化的侦察方法，通过简化单机的性能要求和少数几部侦察机组网，即可实现干扰引导的目的。在总结现有的客观评估方法基础上，提出了利用人类视觉系统（HVS）特性和对比敏感度函数（CSF）的客观评估方法，使已有的客观评估指标能够反映出人眼的主观感受。由此还提出了针对人眼视觉优化的距离像预处理方法，并提出了通过FFT快速实现的距离像调制。最后总结了论文的研究工作和主要创新点，讨论了需要进一步研究的内容。本文研究的基于微动特性SAR干扰是一种有效的和易于工程实现的压制干扰技术，具有四大突出优点：一是可获得部分方位向增益，弥补干扰信号处理增益的劣势；二是可通过优化距离向转发信号的设计，提高目标的抗检测性能和视觉干扰效果；三是对侦察系统的依赖性较低，特别是固定阵地保护应用中可采取若干简易侦察机组网工作方式，实现干扰的引导功能；四是具有对SAR/GMTI的干扰能力，可同时保护地面静止目标和运动目标。在研究干扰技术的同时，本文获得了另外的两项成果：第一是修正了现有SAR观测下微多普勒特性，给出了模型简化必须符合的若干条件，并提出可以利用不同微运动的微多普勒差异作为特征提取的研究方向；第二是提出了基于人眼视觉特性的SAR干扰评估指标，丰富了SAR干扰评估方法。本文研究的基于微动特性SAR干扰，在丰富电子对抗理论的同时，有望提高地面重要军事动目标在SAR/GMTI探测下的生存能力，在国防建设中具有重要意义。更多还原

【Abstract】 Synthetic Aperture Radar (SAR) with Ground Moving Target Indication (GMTI)capability has increasingly become an important means of strategic reconnaissance andbattlefield surveillance systems, poses a sever threat to important military targets.Therefore the jamming technology for countering SAR/GMTI has become an importantnew issue in Electronic Counter Measure (ECM) area. A method against SAR andGMTI is introduced which is based on the micro-Doppler phenomenon that takes placewhen ISAR observes a micro-motion target, and a jamming technology imitatingmicro-motion is basically formed.In the beginning, the background and significance of this research subject areillustrated, and the present status of SAR ECM techniques, including SAR system andjamming evaluation techniques are introduced. The types, development history,development trend and existing problems of SAR jamming techniques are especiallyanalyzed. The present status of SAR/GMTI jamming techniques is further summarized.The major research efforts of this dissertation are also explained.Based on observation vector model, two time-frequency models in Doppler domainare separately established by investigating two typical kinds of micro-motion targetswhich are uniform rotation and vibration. The models are more accurate than preciousstudies. It is proposed that the micro-Doppler differences among various micro-motionscan provide SAR/ISAR some new features for target recognition. The simplifiedDoppler models are summarized and the simplified conditions are analyzed accordingtypical SAR observation status.Starting with the simplest situation that a stationary bulk with only onemicro-motion scatter center, other3situations are all analyzed, that are bulk translation,multiple micro-motion scatter centers and micro-motion across range cells duringimaging time. Imaging features are obtained for each circumstance. Next, consideringthe Doppler history difference between micro-motion objects and real targets thatdistribute along azimuth direction, defocusing phenomenon is analyzed which results inrange migration correction, and constrains are given to avoid defocusing. The potentialof rotating reflectors deployed as a passive jammer is demonstrated by an airborne SARexperiment. Finally, the potential of a micro-motion type jammer to interference SARautofocus is qualitative analyzed, taking an instance of Mapdrift autofocus.Three well-known GMTI technologies based on multi-antennae are taken intoaccount, micro-motion targets’ amplitude and phase characters are analyzed in eachGMTI method. Results show that micro-motion modulation has an ability to interfereGMTI. It turns out that the micro-motion modulation interference will still work onFrFT technology. The micro-motion analogy jamming technology is proposed based on upperresearch. Power demand is analyzed in the first place. The parameters adjustmentpolicies are concluded considering different jamming effects and jamming objects. Also,in order to extend the jamming energy to cover range direction, the micro-motionanalogy jamming combined with fixed noise samples is proposed, which is named“azimuth coherent noise” style. The jamming effects are shown with a example whichmodulates noise samples by frequency modulation. For military protection of fixedpositions, the article also provides a simplified method of reconnaissance, by a networkcomposed with several reconnaissance equipments with low performance requirements.This method can achieve the task to pilot a jammer.On the basis of concluding existing objective evaluation methods, some improvedobjective evaluation methods are presented. By means of implementing human visualsystem (HVS) models and contrast sensitivity function (CSF), those current objectiveevaluation methods can somehow reflect subjective feelings of human eyes. Thisadvantage is improved by some simulations presented in this paper. This paperconcludes with how to use HVS characteristics to pretreat envelope fluctuation alongrange direction, and how to use FFT-based approach to modulate pretreated profile.Simulation results indicate that the performance of azimuth coherent noise interferenceis improved.In the end, this paper summarizes the research work and main innovations, anddiscusses the future work to be researched.After all, the novel suppressing jamming based on micro-Doppler is effective andfeasible in practice, which has four prominent advantages. Firstly the micro-motionmodulation jamming signal can be processed partially coherently in azimuth, which canmake up for the jamming inferiority in processing gains. Secondly its jamming effectcan be improved both in anti-detection and visual observation by optimizing rangerepeating signal. Thirdly it has weak dependency on reconnaissance systems, especiallywhen protecting a fixed position; it can guide jammers with a network assembling byseveral simple reconnaissances. Fourthly it allows for interfere GMTI, and can protectthe stationary and moving targets simultaneously. While studying the jammingtechnique, this thesis approaches another two achievements. One is to amendmentnowadays micro-Doppler models under SAR observation, and the simplificationconditions are given. Furthermore, it implies that thoes micro-Doppler differences maybe the features to be extracted to distinguish various micro-motions. The otherachievement is the presentation of SAR jamming assessment indexies based on humanvisual system. These enriche the SAR jamming effect evaluation methods. Themicro-motion modulation jamming technique constructed in this dissertation, not onlyenriches the electronic countermeasure theory, but most promisingly improves thesurvivability of important ground military targets against SAR/GMTI, which has an important meaning in national defense.更多还原