【作者】 刘庆富；

【导师】 王雪松；

【作者基本信息】 国防科学技术大学 ， 信息与通信工程， 2013， 博士

【摘要】 以扰乱和破坏合成孔径雷达（SAR）成像为目的的干扰技术是当前电子对抗领域的一个研究热点和难点。现有SAR干扰技术虽已初具规模体系，但在应对新体制SAR成像和SAR抗干扰方面仍存在诸多不足，发展新的SAR干扰技术任务紧迫且意义重大。本文以现阶段SAR干扰所面临的挑战为着眼点，以提高地面目标的电子防护能力为目的，深入研究SAR干扰的新方法和新技术，主要工作包括：一、SAR信号截获与参数估计方面（1）针对低信噪比条件下单比特FFT难以检测线性调频（LFM）信号的问题，提出了基于单比特相位差计数的检测方法。该方法通过正交单比特相位差计数器估计单个时段的中心频率，再根据多个时段的频率估计结果检测LFM信号。分析表明：单个时段频率估计的均方差与信噪比成正比，与积累时间的均方根成反比；该方法检测概率和虚警率均可通过改变积累时间和时段个数来灵活控制。（2）针对传统脉冲重复间隔（PRI）估计方法只利用信号上升/下降沿信息的缺点，提出了基于循环互相关的PRI精确估计方法。该方法通过检测相邻两个脉冲互相关的峰值点位置来间接地估计PRI。理论和实验均表明：该方法的估计精度随着信号时宽带宽积的增大而提高，其精度要优于传统方法。（3）针对多普勒调频斜率估计的难点，提出了基于相位双差的估计方法。该方法通过提取相邻两个来波信号互相关峰值点的相位来估计瞬时多普勒频率，通过比较两个不同时刻的多普勒频率得到多普勒调频斜率的估计。分析表明：在经过互相关峰值位置检测、质心频率补偿和克服收发隔离耦合之后，该方法可以获得较好的估计性能。二、SAR二维相参调制干扰方面（1）针对低侦察依赖度相参调制干扰的需求，提出了周期调制干扰方法。该方法通过对SAR信号在快/慢时间上调制任意周期波形来形成干扰，通过改变调制波形的周期和形状来控制干扰的能量分布。轨道SAR对抗实验表明：该方法可形成由离散点构成的线/面假目标，对侦察的依赖度较低，适用于区域遮蔽和对目标成像特征的破坏。（2）针对高分辨成像条件下卷积干扰运算量大、难以实时实现的问题，提出了乘积调制干扰方法。该方法根据虚假目标的散射系数模型来确定干扰的调制波形，而后仅对SAR信号做乘积调制来形成干扰。分析和实验均表明：该方法可形成任意形状的虚假目标，与卷积干扰相比其所需实时运算量要大为降低，尤其适用于在高分辨大场景条件下的欺骗假目标生成。（3）针对SAR成像处理的薄弱环节，提出了误导PGA自聚焦的干扰方法。该方法通过在不同的距离分辨单元形成虚假特显点来误导PGA的相位误差估计，通过改变误导相位来控制干扰之后图像的散焦效果。分析表明：该方法是一种既区别于欺骗干扰又区别于压制干扰的新型干扰方法，其所需的干扰发射功率较低，对侦察的依赖度也很低。三、InSAR干扰方法研究方面（1）针对二维干扰的InSAR成像特性分析需求，研究了单天线干扰的“斜坡”效应。对比单天线干扰的InSAR主/辅通道成像结果得到了干扰的干涉相位，通过分析数字高程反演得到了“斜坡”效应的形成机理。分析表明：采用单天线的任意波形相参调制干扰均存在“斜坡”效应，并且“斜坡”坡度仅取决于干扰机真实位置相对于InSAR的几何位置关系，而与干扰自身的波形调制无关，也与InSAR的基线长度、基线倾角以及发射信号参数无关。（2）针对单天线干扰难以控制InSAR高程反演的问题，提出了基于双天线幅相控制的干扰方法。该方法通过改变双天线干扰的幅度比和相位差来控制虚假目标的合成干涉相位，通过限定幅度比变化范围和设定相位差选取点来实现对合成干涉相位的最优控制。分析表明：该方法可形成逼真度较高的虚假目标，且还可干扰InSAR的图像配准。更多还原

【Abstract】 With the purpose of jamming and obstructing the hostile imaging, SyntheticaAperture Radar (SAR) Electronic Counter Measures (ECM), which has been developeddecades ago, is still a hot and challenging topic in the area of ECM. However, the rapiddevelopments of both new SAR systems and SAR Electronic Counter-CounterMeasures (ECCM) may obsolesce the out-of-date SAR ECM technologies who arepreviousely designed only to counter the old version SAR systems. So the need todevelp new SAR ECM technologies is indubitable and of great significance. With thepurpose to improve the ECM ability of ground targets and also to face the challengesbringed by both new SAR systems and SAR ECCM, this dissertation is dedicated to thedevelopment of new theries and new thechnologies of SAR ECM. The main work ofthis dissertation is presented as follows.Ⅰ.The intercept and parameter estimations of SAR signal(1) Linear Frequency Modulation (LFM) signal detection based on monobitquantification technology. The carrier frequency of LFM signal is estimated byutilizing monobit phase-gradient counters. And the performance of this method is alsoanalyzed to demonstrate that, the standard deviation of the frequency estimation error isproportional to Signal-to-Noise Ratio (SNR), and is reversely proportional to the squareroot of cumulate time. To support the signal detection method, the frequency estimationresults of Gaussian white noise is also researched and demonstrated that, its frequencyestimation result follows a uniform distribution with a width equal to the channelbandwidth in volume. The LFM signal detection based on multiple time segments isproposed, and the relationship between the Probability of Detection (PD) and theProbability of False Alarm (PFA) is analyzed with respect to the number of timesegments.(2) Precise Pulse Repetition Interval (PRI) estimation based on Circular Crosscorrelation Function (CCCF). The probability of CCCF peak detection is deducedwith respect to different SNRs, LFM pulse widths, and the channel bandwidths. Thevalidity of CCCF method is further proved by the Instant Polarization Radar (IPR)experiment to demonstrate that, although the SNR is worsened, the informationincluded by the whole LFM pulse can be sufficiently utilized by CCCF method, whichpromises a higher estimation precision than that of regular PRI estimation methods.(3) Doppler chirp rate estimation based on double-difference method. Thedouble difference method is proposed to solve the problem of Doppler chirp rateestimation. A thorough description of this method is also given by this dissertation. Theperformances of CCCF method influenced by CCCF peak position estimation error, thecentroid frequency estimation error, and the no ideal transmit-receive isolation are all analyzed in detail, and the methods to solve the problems above are also proposed inthis dissertation.Ⅱ. Two-dimensional coherent modulated jamming against SAR(1) Periodic modulated jamming. The SAR imaging results of this jammingmethod with arbitrary periodic modulated waveforms are proved in theory to be discretepoints. The imaging results of the jamming are analyzed under four different cases(namely, the periodic jamming in slant-range direction, the periodic jamming in azimuthdirection, the two-dimensional periodic jamming, and the periodic jamming caused byrange-azimuth coupling), and their dependence on SAR parameter estimation precisionare also given in detail. A new inner-field test method of the jamming is proposed tofacilitate the debugging procedures of the jammer. And a rail-way SAR ECMexperiment is designed to test the performances of the jamming. It has been proved theECM experiment that, periodic modulated jamming can be utilized to shield or toobstruct the real targets being imaged by SAR.(2) Multiplication modulated jamming. The mathematical model ofmultiplication modulated jamming is given. By controlling the multiplication modulatedwaveform of this jamming method, the false targets can then be generated with arbitraryshape in SAR image. More analyses are also given to the performances of this jammingmethod, e.g., the jamming’s energy efficiency, the real-time computational burden, andits dependence on SAR parameter estimation precisions. Both the theoretical analysisand the experiment result have demonstrated that, the multiplication modulatedjamming has the ability to forge decoys which look like the real targets. Thecomputational burden of this method is not sensitive to either the decoy size or SARresolution. Therefore, multiplication modulated jamming is especially suitable to workin the circumstance of large imaging field and high imaging resolution.(3) PGA-misleading jamming. The jamming model in phase history domain isgiven, and the method to generate the false prominent points is also given in detail. Therelationship between the PGA error phase estimation result and the amplitude of falsedominant point is analyzed to calculate the needed transmit power of the jammer. Boththeoretic analysis and the simulation result have demonstrate that, PGA-misleadingjamming is new kind of jamming method which is different from both the oppressivejamming and the deceptive jamming. The advantages of this jamming method comefrom the fact that, the needed transmit power of this jamming method is relatively lowand its performances is not sensitive to the parameter estimation precisions of SARsignals.ⅢThe jamming methods against InSAR(1) The “slope” effect of jamming with single transmit antenna. The frequencyspectrum of the jamming with arbitrary waveform modulation is given, and the imaging result of the jamming in both master and slave channels are derived. The interferometricphase of the jamming can be obtained by comparing the phase difference between theimaging results of master and slave channels. Digital Elevation Model (DEM) of thejamming is researched, and the mechanism of “slope” effect is then derived. Thetheoretical anlaysis shows that, the gradient of the “slope” only depends on the relativegeometric relationship between the InSAR and the jammer, but is independent of thewaveform modulation of the jamming, InSAR baseline length, InSAR baseline inclindangle, and the parameters of InSAR transmit signals.(2) Three-dimension jamming based on amplitude and phase control of twojammer antennas. The analytical expression of the combined interferometric phasegenerated by two jammer antennas is deduced as a function of the jamming’s amplituderatio and phase difference. The control of combined interferometric phase by utilizingboth the amplitude ratio transformation method and the equivalent phase differencemethod is researched, and their detailed procedures are also given. It has been shownthat, this method has the ability to control the combined interferometric phase, togenerate the three-dimensional decoy, and at the same time to influence the imageregistration of InSAR.更多还原