Research On Passive Radar Target Detection Methods Based On TBD

Passive radar has the unique advantage of four resistance in electronic warfare.Common sources of radiation include ground sources,satellite sources,airborne and shipborne sources,etc.The synchronous orbit communication satellite radiation source has unique advantages compared with other types of radiation sources,because this kind of radiation source is stationary relative to the ground,the bistatic radar geometry is stable,the beam coverage of the radiation source is large,and the target echo is less affected by the near earth/sea clutter.However,the long distance of bistatic line makes the target detection face the following severe challenges.Firstly,the target echo SNR is very low,so it is difficult to detect the target.Because the satellite radiation source is far from the ground receiving station,the echo signal reflected by the target is drowned by noise,so it is difficult to achieve robust target detection.Secondly,the echo of moving target is difficult to integrate coherently for a long time.Because the target echo SNR is very low,it is necessary to improve the target SNR through long-term coherent integration.However,the time-frequency variation of moving target echo is complex in the long-term observation.After integration,the related peak of the target diffuses in both distance and Doppler frequency dimension,resulting in the loss of integration gain and affecting target detection.Finally,it is difficult to synthesize signals from multiple radiation sources.Considering the limitation of radiation source power,rational use of multi-source in synchronous orbit is an effective way to improve target SNR.However,due to the different location of radiation sources,the echo reflected by different sources has different time-frequency parameters,so it is difficult to synthesize signal directly for a long time.Based on the above problems,this thesis studies the target detection method of passive radar.The specific research contents are as follows:1.The basic principle of target detection for passive radar with satellite source is studied.Firstly,the spatial geometry of a single satellite passive radar system is analyzed.The signal structure of Digital Video Broadcast-Satellite system is studied and the self-ambiguous function of DVB-S signal is analyzed.Secondly,the passive radar signal model is established and two kinds of signal coherent integration methods are studied.Then,two compensation methods for the first order range motion are studied.And then the theory of two-dimensional constant false alarm rate detection under the background of complex Gaussian noise is derived.Finally,DVB-S signals generated by simulation are used to compare the integration gains of the two coherent integration methods.The compensation effects of two first-order distance walking compensation methods are also compared.And the two-dimensional CFAR detector is used to detect the results before and after the compensation respectively.2.A weak target detection method for passive radar with single radiation source is studied and designed.Firstly,the measurement function of the passive radar system is analyzed.The result after first order Radon Fourier transform range compensation of maneuvering target echo is derived.And the approximate expression of likelihood function under complex Gaussian white noise is analyzed.Then the principle of Bayesian filtering and the particle filter track-before-detect method are studied in detail.Then the dynamic equation of weak target detection is established and its solution algorithm is given.Finally,simulation experiments are carried out to verify the effectiveness of the designed method.3.A multi-source fusion target detection method is proposed.Firstly,the mechanism of target detection and location by multi-source passive radar system is explored.Then the principle of binary accumulation is studied,and a method of TBD detection based on multi-satellite source fusion is proposed.Finally,the effectiveness of the proposed multi-source fusion detection method is verified by simulation experiments.