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Study On Methods Of Synthetic Aperture Radar Deception Jamming

Posted on:2016-01-08Degree:DoctorType:Dissertation
Country:ChinaCandidate:B ZhaoFull Text:PDF
GTID:1108330482453143Subject:Signal and Information Processing
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With advantages such as all-day, all-weather, long operating distance, high resolution imaging, synthetic aperture radar (SAR) is commonly applied in both civilian and military fields including resources remote sensing, geographical mapping, warzone surveillance, precision guidance, etc. The electromagnetic countermeasure (ECM) to SAR has attracted significant attention of the international radar community with the increasing application of SAR. As an important developing direction of SAR ECM, deception jamming possesses the advantages of low jamming power, high flexibility, high fidelity, which make it a hot spot of ECM research field. This dissertation proceeds with several key problems with which the SAR deception jamming technology is faced. It aims at enlarging the jamming area, improving the fast realization performance, increasing the applicability of the jamming algorithms, and improving the fidelity of the false target. The principle and method for implementing SAR deception jamming is deeply studied in this dissertation. The main contents of this dissertation are listed as follows:1. Based on the analysis of different SAR imaging modes, a uniform imaging geometrical model is proposed. The physical significance and the formation mechanism of SAR parameters are analyzed, and the basic principle of deception jamming is studied based on the basic principle of imaging processing. The general signal model of SAR deception jamming is established.2. The difficulty for scattered wave deception jamming to perform precise jamming modulation for each false scatterer, because of the limitation of the terrain limits the effective range of deception jamming. Therefore, we proposed a pre-modulating scattered wave deception jamming algorithm based on terrain parameters to deal with the problem of small jamming range. Firstly, the principle of scattered wave deception jamming is deeply studied, and the produce mechanism of the modulation error is analyzed. The range distortion, azimuth stretch, and azimuth chirp rate mismatch are quantitative analyzed to show the effect of the modulation error on the deception jamming result. Then, with the deep research on the uniformity of the false scene distortion, the focusing quality, the energy loss and the system realizability, we gave out the size limitation of the scattered wave deception jamming protecting area. The pre-modulating scattered wave deception jamming algorithm is proposed based on terrain parameters by precisely modulating the time delay of the envelope and the Doppler phase. By doing this, the non-linear distortion and the azimuth chirp rate mismatching are effectively reduced, and the limitation of system realization is also broken. The improved algorithm increases the protecting area of scattered wave deception jamming.3. The point-by-point deception jamming algorithm is able to avoid the distortion of false scene, but it is confronted with the defocusing problem when the jamming scene becomes larger. To solve this problem, we proposed the subsection pre-compensation deception jamming algorithm for a large scene. The existing deception jamming algorithm utilized approximated derivation to simplify the solving relationship between the modulation parameters and the reconnaissance parameters, which inevitably introduced modulation error. The large deception jamming algorithm divides the large scene into subsections and designs different pre-compensation parameters based on the analysis on focusing depth, which solves the problems caused by the range migration difference and the Doppler phase history variation in range. The parallel processing and the two-step spectrum dimensional division processing are utilized to improve the real-time performance of the algorithm. The simulation results shows that the proposed subsection pre-compensation deception jamming algorithm enlarges the protecting area and possesses high computational efficiency.4. To deal with the problems of inaccurate detected or incomplete parameters during the process of deception jamming, we proposed a deception jamming with synergy networking receivers. By constructing linear equations with the accurate time delay differences of the intercepted signals measured by multiple receivers and further solving the modulation coefficients with optimization method, the effect of error accumulation caused by inaccurate detected parameters on jamming result can be avoided. The deception jamming algorithm based on synergy networking receivers is able to solve the accurate modulation parameters under the near field condition, which ensures the accuracy of deception jamming effectively. Under the far field condition, we can use the approximate algorithm to reduce the complexity of the system. Considering the underlying measuring error, we further proposed a redundant deception jamming algorithm to perform an optimal denoising on the solved jamming coefficients. Based on the jamming range analysis, the suggestion for networking strategy under different conditions is given.5. To solve the problem of low fidelity of the false target generated with point scatter model, an accurate deception jamming modulation method based on the electromagnetic properties of the target is proposed. With the steps such as modeling the typical target in three dimensional, calculating the electromagnetic scattering properties, solving the attitude angles in real-time, and precisely modulating, the multiple scattering, shadowing, and other effects between different assemblies of the typical target can be accurately simulated and modulated to the jamming signal. This increased the fidelity of SAR deception jamming observably.6. The processing load, real-time performances, equipment complexity, and fidelity of false target are analyzed and compared among different algorithms. The applicability and synergic working relationship of different SAR deception jamming algorithms are given. Firstly, a method utilizing approximate quantizing convolution modulation is proposed for synergy networking receivers deception jamming to guarantee its fast realization performance. It is also compared with the two-step spectrum dimensional division processing method for large scene deception jamming in terms of the applicability. The complexity of equipment for realization is also presented based on the analysis of computation load. Then, we analyzed the fidelity of different deception jamming algorithms by considering the false scene distortion and the effect of the motion errors on deception jamming results. Finally, for all the proposed deception jamming algorithms, their integrated properties, as well as the cooperating relations are discussed, which provide the basis for the selection of different deception jamming algorithms in practical application.
Keywords/Search Tags:Synthetic Aperture Radar, Deception Jamming, Scattered Wave DeceptionJamming, Synergy Networking Receivers Deception Jamming, Accurate Electromagnetic Properties Modulation, Jamming Performance Analysis
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