Waveform Design Of Anti-active Deception Jamming And Signal Coherent Processing Method

Increasingly complicated electromagnetic jamming exists in the working environment of modern radar,especially the active deception jamming,its high similarity with the radar signal poses a great threat to the target detection and tracking of the radar.In order to ensure the working effect of radar,various methods for anti-jamming have emerged.However,traditional anti-jamming techniques based on signal processing are prone to problems such as distortion of echo signals and incomplete jamming suppression.In recent years,with the maturity of waveform generation technology,modern anti-jamming methods have gradually shifted from "passive" signal processing to "active" waveform design.Based on the in-depth understanding of various types of typical repeater deception jamming,this thesis designs a variety of anti-jamming coding waveforms for different jamming scenarios,Especially in the face of compound repeater deception jamming in the environment,an anti-jamming waveform with interpulse-intrapulse joint frequency coding is proposed,which can simultaneously counteract cross-pulse repeater deception jamming and interrupted sampling repeater jamming.However,complex modulated waveform may cause the originally coherent signal to become noncoherent due to the agility of parameters even if it has excellent anti-jamming performance.In order to solve the problem of coherent accumulation of anti-jamming waveforms,this thesis proposes corresponding signal coherent processing methods for the proposed waveforms.The central research contents of the thesis are as follows:1.The anti-jamming waveform design and signal processing method for cross-pulse repeater deception jamming are studied.Three anti-jamming waveforms are introduced for cross-pulse repeater deception jamming,including orthogonal binary phase-coded signal,Costas frequency coded signal and frequency agile joint PRF-jittering signal;the signal model construction and anti-jamming characteristic analysis of the three waveforms are carried out,and a signal processing method based on grouped coherent accumulation is proposed for frequency coded signal,which solves the problem of coherent accumulation of signals due to parameter agility.The anti-jamming performance of the three coded waveforms is verified through simulation and measured data.It can be verified by the coherent accumulation simulation result of frequency coded signal that the algorithm of grouped coherent accumulation can effectively realize the coherent accumulation of frequency coded waveform.2.The anti-jamming coding waveform design and coherent processing method for compound repeater deception jamming are studied.An interpulse-intrapulse joint frequency coded signal is proposed for the compound repeater deception jamming composed of cross-pulse repeater deception jamming and interrupted sampling repeater jamming in the environment,and then the signal model is established and the ambiguity function characteristics are analyzed.The anti-jamming process of the coded signal is described in detail,and a design method of intra-pulse frequency code based on jamming perception is designed,which reduces the influence of the transition band jamming on the target subsegments.Then,two coherent accumulation methods of intrapulse-interpulse joint frequency coded signals are proposed for different coding methods,namely: the coherent accumulation algorithm based on subpulse sorting and different frequency rearrangement,and the NDFT-based coherent accumulation algorithm,then the effectiveness of the two algorithms is verified by simulation.Finally,the anti-jamming performance of the proposed coded signal in different environments is verified by simulation experiments.The results show: the intra-pulse frequency code based on jamming perception can effectively reduce the influence of residual interference from the transition band on the target subsegments,the two proposed coherent accumulation algorithms can effectively realize the coherent accumulation of interpulse-intrapulse joint frequency coded waveform,the interpulse-intrapulse joint frequency coded signal can suppress the compound repeater deception jamming effectively in the environment.