Study On Design Method Of Radar Anti-jamming Waveform

The increasingly complicated electromagnetic environment has brought severe challenges and threats to radar.On the one hand,dim targets such as stealth aircraft may be submerged in the sidelobe of strong echo targets;On the other hand,the deception jamming formed by the DRFM jammer is strongly correlated with the radar transmission waveform,resulting in the decline of the discrimination and suppression ability of the radar receiver,The above factors will seriously affect the target detection ability of the radar.Because the performance of low sidelobe and deception jamming suppression depend on the design of transmitting waveform,and with the continuous improvement of waveform optimization theory,the traditional waveform design gradually develops towards the cognitive waveform with environmental perception ability.Therefore,this thesis mainly focuses on the design of radar cognitive low sidelobe waveform and the analysis of its anti-deceptive jamming performance.This thesis focuses on the design of radar transmitting waveform from the two aspects of low sidelobe and anti-deception jamming.In this thesis,the gradient algorithm is used to design the orthogonal waveform set,and the fuzzy function is used to analyze the frequency stepping signal and give its signal processing method.The main research contents are as follows:1.Aiming at the problem that it is difficult to further reduce the autocorrelation sidelobe level and cross-correlation level of orthogonal waveform designed based on PSL and ISL criteria under the constraint of waveform optimization degree of freedom,this paper proposes a modified radar anti-jamming waveform design method based on gradient descent,This method combines the actual working scenes of radar and electronic interference,and designs a new anti-jamming waveform optimization criterion,so as to improve the freedom in waveform optimization under the same conditions and further reduce the waveform sidelobe level to a certain extent.The simulation analysis shows that the orthogonal waveform set obtained by the waveform optimization method proposed in this paper has greater advantages in anti-intermittent sampling and forwarding interference than the traditional design method.2.Aiming at the problem that the high sidelobe of one-dimensional range profile of linear step frequency signal makes it difficult to detect dim targets in complex background,this thesis proposes an optimization method the jump rule of carrier frequency between waveform pulses based on window function,which makes the signal energy unevenly distributed in the spectrum,so as to effectively suppress the high range sidelobe level of onedimensional range profile.The simulation results show that the nonlinear frequency stepping technology between pulses has obvious advantages over the linear frequency stepping technology in weak and small target detection in complex environment.3.Aiming at the problem of radar anti-jamming waveform design in the presence of multiple deceptive jamming at the same time,this thesis finally proposes a composite modulation waveform,which combines the orthogonal phase coding waveform optimized in this thesis with the frequency stepping signal.The simulation results show that the orthogonal phase coding waveform is modulated in a single pulse of the linear stepping frequency signal.The simulation results show that the composite modulation waveform obtained by modulating the orthogonal phase coded waveform in a single pulse of the linear step frequency signal can effectively suppress the intermittent sampling forwarding jamming and the full pulse sampling false target jamming with one pulse delay.When the nonlinear step frequency technology is used between pulses,the composite modulation waveform not only has the advantage of anti-interference under the linear frequency technology,but also can improve the detection performance of the near main lobe dim targets.