| Passive bistatic radar attracted the attention of researchers over the past decade because of its many advantages such as no electromagnetic pollution, anti-stealth mis-sile, hard to and low cost. Accompanied by the research carried by domestic and foreign research institutes focus on the passive bistatic radar, there has been a lot of break-throughs in theoretic research and technology implementation. Meanwhile, emerging new application scene brought a great many of new task, needs to be addressed. Around specific scenarios such as how to achieve optimization of array configu-ration, how to suppress the direct wave interference and how to implement real-time signal processing, based on several key techniques of array signal processing, this thesis research and in particular are as follows.1. Based on the poor performance of conventional arrays in specific scenarios, A di-rectivity optimality criteria suit for max distant detecting and peak sidelobe ratio (PSLR) guidelines suit for omni-directional coverage Is presented. The relationships of directivity and array coordinate, one-dimensional array spacing small perturba-tions and the corresponding sidelobe level, was discussed. Two typical scenarios of passive radar array configuration optimization problem in case of limited number of array elements were solved.2. Based on the characteristics of the Digital Radio Mondiale (DRM), a new method of array calibration for high-frequency passive radar (HFPBR) by using frequency reference signal of direct wave is proposed. Firstly the signal structure of DRM is introduced, while the feasibility of take frequency reference signal as the calibration source is demonstrated. Secondly, taking into account the electromagnetic envi-ronment and time-varying non-stationary propagation characteristics, a method of choosing high quality direct wave period by the shift-invariant antenna pairs is proposed. Finally, assist by the known DRM transmitter position, we utilized this method deal with measured direct wave data which propagate in surface wave mod- e and sky wave mode, compared the result of array calibration value with known single frequency signal source. The results showed that the amplitude and phase compensation method in DRM-based HFPBR is effective.3. Conventional adaptive beam-forming technology has poor proformance in the rigid-ity of direct-path interference. Null direct-path interference beamforming schemes based on linearly constrained minimum variance (LCMV) beam-forming was pro-posed. Robust Adaptive Null direct-path interference beamforming schemes based on using the covariance matrix of cone (CMT) technology was proposed. This the-sis implements direct-path interference effective suppression, clutter power reduced, improved target detection performance of the system in passive radar.4. FM based passive radar faces some issues such as time varying bandwidth and RCS glint, a multiple FM joint detection scheme is proposed, and the corresponding experiments with passive radar system developed by Wuhan University are car-ried out. First, the process flow of multi-FM based Passive Radar is introduced. Then, the signal characteristics of multi-FM for radar application are analyzed, meanwhile, the necessity and advantages of multi-FM scheme are demonstrated. Finally, the relationships between target detection probability and the number of FM broadcast used are derived, moreover, the practical processing results are p-resented. Experiment result proves that multiple frequency detection scheme can substantially improve target detection performance, enhanceing the robustness of passive radar system.5. Passive radar need to face computational complexity problems with large bandwidth signal. Based on GPU parallel computing techniques, the DTMB signal real-time processing solutions was proposed. The scheme of parallel processes for signal reconstruction, clutter, matching match filtering,based on CUDA architecture was presented. Developed modular software, through the testing of many continuous data at different times to achieve 8 MHz bandwidth signal real-time processing. |
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