Research On Interference Suppression Of Non-cooperative Radar Transmitter Based Passive Radar

Using non-cooperative radar as illuminator to detect,localization and tracking target,the passive radar system has the advantage of long detection range,good RF stealth,great anti-stealth and high altitude coverage,therefore it is gradually become the focus of research.However,due to the large transmit power of non-cooperative radar signal and complex beam scanning pattern,traditional interference cancellation algorithm cannot effectively suppress direct-path and multipath interferences,which seriously affects the subsequent target detection.Therefore,the effective interference suppression technology has become a key problem to be solved in the study of non-cooperative radar illuminator passive radar.Firstly,this thesis analyzed the non-cooperative radar emitter and established the passive radar signal model.Then,discussed the various types of passive radar interference in the real environment and analyzed its influence of the existing interference suppression algorithm.Finally,this thesis improved current interference suppression algorithm,proposed a set of interference suppression technology which will suitable noncooperative radar illuminator passive radar.The main contents of this thesis are as follows:1.Analyzed the non-cooperative radar emitter and established the passive radar signal model according to its characteristic.Based on the analysis of the possible interference types in the main channel of the passive radar system in real environment,the spatial and temporal signal processing models are established.2.Studied using time domain adaptive interference suppression algorithm to suppress direct-path and multipath interference in main channel of passive radar.Proposed an improved cancellation algorithm(FDB-ECA algorithm on the condition of poor correlation between main channel and reference channel which caused by fractional delay interference and channel frequency characteristic inconsistent,target signal modulation and large interference suppression residual which cause by extend batch cancellation algorithm uniform segmentation.The FDB-ECA algorithm can keep the Clutter Attenuation ratio(CA larger than 40 dB on the environment of fractional delay interference and channel frequency characteristic inconsistent and the CA can up to 95.69% of the theoretical boundary.The improved algorithm can also solve target modulation and large interference suppression residual and has a relatively low computational complexity.3.This thesis proposed an improved space-time joint interference suppression algorithm as the result of purely use temporal method have distance blind and purely use space domain processing have range blind.The proposed algorithm not only reduces the detection blind area,but also effectively solves the problem that interference angle of the distributed source is wide.4.The effects of distributed source interference,array phase error and other factors on the space domain processing are analyzed and corrected by using the wide nulling method and the single auxiliary source algorithm.Analyzed and designed the passive radar simulation system,and use MATLAB GUI to achieve it.At last,the effectiveness of the interference suppression algorithm is verified from the perspective of target detection.