Analysis And Test Of Active Coherent Jamming For Millimeter-Wave Missile-Borne Radar

In recent years,with the development and widespread application of digital radio frequency memory,jamming has become increasingly threatening to missile-borne radar.Active coherent jamming is one of them.Active coherent jamming is generated by modulating the intercepted radar signal.In the case of jamming,the coherent jamming can effectively degrade the detection and tracking performance of the radar with only a relatively small jamming power.At the same time,the jamming is coherent with the radar signal,which is difficult to be suppressed or eliminated by traditional anti-jamming methods.Therefore,this thesis focuses on the problem of active coherent jamming faced by millimeter-wave missile-borne radar.Firstly,the principle and characteristics of the coherent jamming are analyzed and studied.Then,based on the characteristics of coherent jamming in the time-frequency domain,anti-coherent jamming methods are studied from three aspects: jamming identification,jamming separation,and anti-jamming waveform design.Finally,a complete anti-coherent jamming signal processing process has been formed.The work arrangement of the thesis is as follows:1.Aiming at five typical types of active coherent jamming,namely,noise convolution jamming,noise product jamming,interrupted-sampling directly jamming,partial-pulse dense transmit jamming,and whole-pulse dense transmit jamming,a coherent jamming scenario and mathematical model are constructed,and the principle and characteristics of coherent jamming are analyzed in time,frequency,and timefrequency domains.According to the characteristics of coherent jamming,intelligent recognition algorithms based on LSTM and residual CNN networks and intelligent recognition algorithms based on CNN are studied.The network is used to extract timedomain-derived features to identify coherent jamming.The influence of jamming-tosignal ratio on recognition performance is analyzed through simulation.2.Aiming at the difficulty in separating five typical types of active coherent jamming,the research is carried out in spatial,time,and frequency domains.Aiming at stand-off jamming,a separation method based on spatial filtering is studied using the spatial difference between the jamming and target signal;Aiming at self-defense active coherent deception jamming,a method of jamming separation based on energy detection and dechirp is studied using the energy domain characteristics of the jamming and target signal when they are mixed;Aiming at suppressing jamming,the mixed signals are separated by blind separation.Finally,simulation analysis of various separation methods for jamming separation effects.3.The anti-coherent jamming waveform design method is studied from the perspective of waveform design.Aiming at the forwarding characteristics of inter-pulse active coherent jamming,a waveform design method based on chaotic phase coding and frequency agility is studied,and the anti-jamming performance of the designed waveform is verified by simulation;Aiming at the characteristics of in-pulse active coherentjamming,a waveform design method based on in-pulse orthogonality is studied.This method uses the obtained jamming sampling information to design an in-pulse segmented orthogonal combined waveform and uses segmented pulse compression to suppress jamming.Finally,the anti-jamming performance of the designed waveform is analyzed through simulation.