Research On Agile Waveform Against Radar Novel Active Jamming Technology

With the rapid development of digital radio frequency memory technology,modern jammers have the characteristics of stronger power,higher sensitivity,wider frequency band,and faster response speed,which pose a serious threat to the survivability of radar in the battlefield.In addition,the novel active jamming patterns that have appeared in recent years have the characteristics of flexibility and change.Through the dynamic adjustment of jamming parameters and the design of the timing relationship between sampling and repeating,the novel active jamming can display the jamming effect of suppression or deception,which brings great challenges to the detection and tracking of radar.Aiming at this problem,this paper conducts research on agile waveform anti-radar novel active jamming technology,realizes active jamming suppression and target echo identification,and improves radar anti-novel active jamming capability.The specific research work is as follows:(1)A detailed theoretical analysis and research on smart noise jamming,frequency-shifting repeater jamming,dense false target jamming and interrupted sampling repeater jamming are carried out from the four aspects of principle,mathematical model,mechanism and characteristics after pulse compression.At the same time,the theoretical analysis results are verified by simulation experiments,which lays a foundation for the subsequent jamming suppression.(2)Focusing on frequency agile radar anti-dense false target jamming research,dense false target jamming suppression algorithm based on frequency agility and waveform entropy is proposed.According to the difference between the target and the jamming trajectory in the fast-slow time two-dimensional plane under the frequency agile radar,the algorithm uses waveform entropy to identify the target and jamming.Then the jamming sidelobe in the echo data after jamming suppression is removed by local outlier factor.Finally,the twodimensional sparse reconstruction algorithm is used for the coherent integration.Simulation experiments and measured data processing results verify that the proposed algorithm can effectively suppress dense false targets jamming.In addition,compared with the same type of anti-jamming algorithm,the proposed algorithm has a great improvement in anti-jamming performance because it removes the jamming sidelobe existing in the echo data after interference suppression.(3)Focusing on frequency coding waveform anti-interrupted sampling repeater jamming research,anti-interrupted sampling repeater jamming algorithm based on frequency coding waveform and modified discrete chirp-fourier transform is proposed.According to the timedomain discontinuous sampling characteristics of the jamming,the algorithm firstly separates each sub-pulse by frequency domain filtering.Then,according to the idea of feature extraction and classification,the unjammed sub-pulse is extracted,and the jamming signals in the jammed sub-pulse are suppressed by transform domain filtering to improve the anti-jamming performance of the algorithm.Finally,for the problem of grating lobes in pulse compress results caused by spectrum discontinuity,the sub-pulse frequency domain synthesis method is proposed.The simulation results verify that the proposed algorithm can not only effectively suppress the interrupted sampling repeater jamming,but also effectively suppress the grating lobes existing around the target,realize radar detection and tracking of the real target.The performance analysis results show that the signal-to-jamming ratio improvement of the proposed algorithm is better than that of the same type of segmented pulse compress anti-jamming algorithm.