Study On Reconnaissance And Jamming Methods Against SAR/InSAR

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the rapiddevelopments of both new SAR systems and SAR Electronic Counter-CounterMeasures (ECCM) may obsolesce the out-of-date SAR ECM technologies who arepreviousely designed only to counter the old version SAR systems.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.