Research On Methons Of Anti-active Jamming In Radar

In electronic countermeasures,jammer can reduce the detection and tracking ability of radar system as much as possible by transmitting all kinds of jamming signals,while radar system needs to improve the ability of detecting and tracking targets in complex electromagnetic environment.They are like the relationship between spear and shield.The development of new radar detection technology is bound to be accompanied by the development of jamming technology.The essence of anti-jamming technology is to extract the feature difference between the jamming signal and the real target signal in different dimensions,suppress the energy of the jamming signal or enhance the energy of the real target signal.In order to improve the anti-jamming ability of radar system,this paper discusses the signal models of active suppression jamming and active deception jamming.Than,analyzes the realization of jamming perception,jamming suppression and target detection of radar system by combining frequency agility,Hough transform,OFDM modulation and other technologies.The work of this paper is as follows:(1)A typical active radar jamming signal model is established.The mathematical model of interference signal is given,and the simulation results in time domain and frequency domain are given,which lays the foundation for the interference suppression algorithm in this paper.(2)The interference suppression algorithm of frequency conversion combined with Hough transform is proposed to against the dense forwarding spoofing.The signal model of the frequency agile radar is established,and the distribution characteristics of the interference under the frequency agile system are analyzed.The interference suppression and target information extraction are realized by combining the Otsu algorithm and Hough transform technology.The target detection is realized by using the compressed sensing and the minimum waveform entropy.The effectiveness and practicability of the method are verified by the simulation experiment and the analysis of the measured data.(3)An anti active jamming algorithm of frequency agile radar based on OFDM modulation is proposed.In this method,OFDM modulation and frequency agility technology are used to avoid most of the interference.The interference sensing method is used to eliminate the subcarriers with high-power interference signals.The remaining subcarriers with only the target signal are sparse reconstructed to complete the high-resolution synthesis of the target range image,and then the average speed and initial distance of multiple targets are estimated simultaneously by EM algorithm.Simulation results show that this method can effectively achieve interference suppression and multi-target detection.