Radar Anti-jamming Methods Based On Waveform Design With Optimization Theory

Interrupted sampling repeater jamming is an active forwarding jamming which can deceive coherent radar effectively.It is generated by the jammer intercepting and sampling and forwarding radar transmitted signals.After pulse compression,a series of false targets can be generated.In this thesis,based on the analysis of interference characteristics and cognition of interference,waveform design methods based on optimization theory against interrupted sampling repeater jamming are studied.Firstly,the mechanism and characteristics of different types of active forwarding jamming are analyzed.The effect of interrupted sampling repeater jamming under LFM(Linear Frequency Modulation)signal,the relationship between peak amplitude,number and distribution of false targets and jamming parameters are studied emphatically.Finally,the basic flow of radar echo processing and the theoretical basis of anti-jamming waveform design and modeling are introduced.To solve the cognitive problem of interrupted sampling repeater jamming,two methods are studied in this thesis.The first one is based on the correlation of signal envelope for the interference type identification and parameter estimation,which has a wider applicability.Based on the special time-frequency characteristics of LFM,a second scheme for interference cognition is put forward,consisting of time-frequency analysis as well as the processing of deconvolution.This method is easy to implement,and the impulse pairs of the deconvolution results can achieve more accurate estimation of the width of interference slices.The feasibility of the two schemes is verified by analysis in theory and simulation results.To suppress interrupted sampling repeater jamming,different methods are proposed in this thesis from two aspects of signal processing and waveform design.The two methods based on signal processing can effectively suppress the interference of the three forwarding modes under certain conditions,but their performance is limited by the power and ratio of interference respectively.The two methods based on waveform design establish models based on the criteria of minimizing ISL(Integrated Sidelobes Level)and maximizing the matched-degree of ambiguity function template respectively,and the algorithm framework such as MM-Minimization)(Majorization is applied to solve the waveform iteratively.Finally,the anti-interference performance of the waveform,the good convergence and robustness of the algorithm under non-ideal conditions are verified.In this thesis,the receiving and transmitting joint processing method is adopted,avoiding their respective defects while integrating the advantages of the two,effectively realizing interference suppression,and the iterative algorithm with good convergence performance is adopted to solve the waveform.