Research On Novel Active Jamming Suppression Technology For Radar

Conventional active jamming,such as noise frequency modulation jamming,Range Gate Pull-Off jamming and Velocity Gate Pull-Off jamming,etc.have some problems,such as low power utilization,need more accurate frequency guidance and large forwarding delay,which affect the jamming efficiency.In order to interfere with the radar more effectively,in recent years,novel active jamming such as noise convolution jamming,noise multiplication jamming,slice forwarding jamming,full pulse dense forwarding jamming and interrupted sampling jamming have been proposed.Novel jamming has some characteristics that conventional jamming does not have,such as small forwarding delay,pulse compression gain of radar can be obtained,etc.So it will cause great harm to radar,it is necessary to study the suppression methods of novel jamming.The main work of this thesis is summarized as follows:(1)The generation mechanism of noise convolution jamming,noise multiplication jamming,slice forwarding jamming,full pulse dense forwarding jamming and interrupted sampling jamming,the characteristics of time and frequency domain and the jamming effect on radar are analyzed.The mathematical models of these novel active jamming are established.(2)In the time domain,the jamming recognition feature parameters such as the envelope fluctuation,the envelope left-right similarity and so on are extracted,and the jamming identification feature parameters such as the norm entropy,the energy similarity before and after spectrum shaping and so on are extracted in the frequency domain,and the novel active jamming types studied are effectively identified by using decision tree classifier.(3)Based on the strong autocorrelation of LFM signal and weak cross-correlation with noise convolution jamming and noise multiplication jamming,the noise convolution jamming and noise multiplication jamming suppression method based on correlation filtering is studied.(4)Based on the different characteristics of slice forwarding jamming and target echo after dechirp,the method of jamming suppression based on dechirp is studied.By analyzing the frequency domain characteristics of slice forwarding jamming superimposed target echo,the method of jamming suppression based on frequency domain attenuation is given.(5)The anti-jamming method of filtering in autocorrelation domain is improved,and the filtering is changed to pulse compression domain.A full pulse dense forwarding jamming suppression method based on pulse compression domain filtering is given.(6)Based on the analysis of the spectrum characteristics of interrupted sampling jamming,the jamming suppression method based on frequency domain amplitude replacement is studied.Through the analysis of false targets with larger amplitude and smaller amplitude formed by the pulse compression of the jamming signal,the interrupted sampling jamming suppression method based on double pulse cancellation and superposition is studied,and the method based on frequency domain attenuation is applied to the jamming suppression of interrupted sampling jamming.