Research On Anti-repeater Interference Based On Waveform Design And Signal Processing

In today’s complex electromagnetic environment,as a new type of active deception jamming,repeater jamming has received extensive attention due to its strong deception and good jamming effect.The forwarding methods can be mainly divided into inter-pulse forwarding and intra-pulse forwarding.In recent years,researches on the two types of forwarding interference have emerged in an endless stream,but there are relatively few researches on the waveform design for simultaneously resisting inter-pulse forwarding interference and intra-pulse forwarding interference.Therefore,this paper aims to study the signal waveform that can effectively suppress the inter-pulse and intra-pulse repeating interference through the waveform design method,and achieve the suppression of the intra-pulse repeating interference when the dry signal ratio is high through signal processing,and further enhance the anti-interference performance.This paper focuses on the above two aspects,and the main contents are as follows:(1)Aiming at the problem of strong inter-pulse forwarding interference and intra-pulse forwarding interference and good deception effect,this paper proposes a frequency-coded composite modulation signal based on piecewise chirp phase coding.Orthogonality,effectively suppressing two types of interference at the same time.When the signal has a fixed bandwidth,the sub-pulse adopts the composite modulation of piecewise linear frequency modulation and phase encoding,and the frequency encoding is adopted between the sub-pulses,which increases the degree of freedom in the design of the waveform pulse.It not only has the advantages of strong phase-encoded signal flexibility and good quadrature performance,but also has the advantages of large frequency-encoded signal bandwidth and difficult to complete interception by jammers.The simulation results show that the waveform proposed in this paper has a good effect of anti-repeater interference.(2)Aiming at the situation that the signal designed in this paper has uneven performance due to the strong randomness of the coding sequence,this paper designs a waveform design method based on an improved adaptive genetic algorithm.The weighted sum of the crosscorrelation levels is the optimization goal,and the three coding sequences of frequency,bandwidth and phase are jointly searched.At the same level,the effectiveness of the algorithm is proved.(3)Aiming at the problem that the signal designed in this paper has insufficient ability to suppress the interference of intra-pulse forwarding in the case of relatively large dry signals,the segmental pulse pressure based on the Otsu algorithm is studied,and a segmental mismatch filtering algorithm based on the Otsu algorithm is proposed.After simulation analysis,the results obtained by the segment mismatch filtering algorithm are better than the segment matched filtering,which further improves the anti-interference effect.