Study On Radar Technology Against Active Jamming

Since the advent of radar,its jamming and anti-jamming struggle so far.With the development of the jamming technology,the anti-jamming theory and technology of radar have also been promoted.And the continuous development of radar anti-jamming also contributes to the more advanced radar jamming.In modern war,military electronic information technology plays an increasingly weighty role.The struggle between the radar jamming and anti-jamming is also increasingly complex.Therefore,it is of great practical significance to study the anti-jamming technology of radar in complicated electromagnetic environment.Against these challenges,related anti-jamming methods of radar are proposed as below:Firstly,the basic theory of radar jamming and anti-jamming technology is introduced.Through discussing the generation and mechanism of various jamming signals,the time-domain expressions are given and the mathematical models and basic statistical characteristics are analyzed.The jamming signals are also simulated in this part.At the same time,the thesis introduces chaos theory and the common chaotic signal model,which are foundations for the research on chaotic signal anti-jamming.Secondly,to address the problem that the radar cannot recognize the target echo signal under the background of noise amplitude modulation jamming,a noise amplitude modulation jamming suppression algorithm based on fractional Fourier transform is proposed.The algorithm adopts fractional Fourier transform of different fractional order and correlation processing to deal with the received signal.The optimal fractional orders are confirmed by the theoretical analysis and simulation experiments.Eventually the target signal is detected,and the noise amplitude modulation jamming can be filtered out.Again,aiming at the problem that smart noise jamming can produce blanketing and deception jamming effects to the LFM pulse compression airborne radar,a new suppressing method for convolution modulation smart noise jamming with frequency-shift is proposed.In view of the different features of the target signal and jamming,the convolution modulation smart noise jamming with frequency-shift can be effectively separated via the stretch processing.Based on the multi-scale filter characteristic of the EMD(Empirical Mode Decomposition),a new LMS algorithm(EMD-LMS)is proposed to cancel the jamming and then the target echo can be rebuilt.Finally,a new definition of piecewise Logistic chaotic map is proposed.To analyze the anti-jamming performance of the new piecewise Logistic chaotic map,the theory of fuzzy function is used.The new piecewise Logistic chaotic map has ideal pin type ambiguity function.The theoretical analysis shows that the chaotic map anti-jamming performance is good.Using the matched filter to filter the chaotic signal mixed with three strong jammings and calculating the SIR before and after filtering.At last the strong anti-jamming performance of the new piecewise Logistic chaotic map is verified.