Research On Radar Anti-DRFM Jamming Technology Based On Waveform Design

In military electronic countermeasures,the active deception jamming signal based on digital radio frequency memory(DRFM)technology have strong coherence with the radar transmitting signal,which makes it difficult for the receiver to distinguish the real target.Therefore,the research on radar anti-DRFM interference method is of great significance.The DRFM jammer modulates the intercepted transmitted pulse signal by additional delay,frequency or amplitude to generate an interference signal similar to the target echo,and forms strong deception interference at the receiving end.According to the formation mechanism of the DRFM interference signal,the model and interference characteristics of the false target signal are analyzed.Based on the linear frequency modulation(LFM)transmit signal,the orthogonal frequency division LFM signal and the frequency agility LFM signal are studied.Aiming at the problem that the orthogonal frequency division LFM signal has a great influence on the bandwidth of the radar system,an improved anti-interference waveform design method is proposed.The transmitting waveform agility is realized by changing the frequency modulation slope of the orthogonal frequency division LFM signal,and the orthogonal frequency division joint frequency modulation slope agility LFM signal is designed.The correlation and anti-interference performance of the design waveform are analyzed based on the transmitted and received signal models.Based on the phase-encoded transmit signal,an orthogonal discrete phase-encoded signal is studied.Aiming at the complexity of the waveform design algorithm,the chaotic phase-encoded signal is studied,and an improved anti-interference method for waveform design is proposed.The frequency agitation of the transmitted pulse is realized by chaotic coding modulation of the center frequency of the chaotic phase-encoded signal.The transmitting and receiving signal model of chaotic phase-frequency coded radar are designed,and the correlation and anti-interference performance of the waveform are analyzed.The simulation results show that the designed waveform can effectively suppress DRFM interference.The orthogonal frequency division joint frequency modulation slope agile LFM signal effectively solves the problem of wider bandwidth of the radar system of orthogonal frequency division LFM signal,and improves the anti-jamming performance by 7dB under the same frequency difference;the anti-jamming performance of chaotic phase-frequency coded signal is improved by 8dB compared with chaotic phase coded signal,and the complex problem of the design algorithm of orthogonal discrete phase coded signal is effectively solved The improved waveform effectively improves the anti-jamming performance of radar system,which provides a reference for the anti-jamming research of radar waveform design.