Research On Interference Identification And Anti-interference Algorithm Of Linear Frequency Modulation Continuous Wave Fuz

With the advantages of no distance dead zone,high distance resolution,and strong antijamming ability,LFMCW fuzes are now widely used in the military field,and electronic countermeasures against LFMCW fuzes are receiving more and more attention from researchers.The repeater jamming based on digital radio frequency memory(DRFM)technology poses a serious threat to the battlefield capability of LFMCW fuzes because of its high coherence,quick response and large instantaneous bandwidth.In this thesis,aiming at DRFM jamming,the jamming identification method and the jamming suppression method were studied.The main research contents are summarized as follows.(1)The jamming mechanism of conventional dummy target jamming,Smeared Spectrum(SMSP)jamming and Chopping and Interleaving(C&I)jamming on LFMCW fuzes was analyzed,and the jamming effect was simulated on this basis.The simulation results showed that SMSP jamming has a suppressive and deceptive double jamming effect,and has the strongest jamming capability on LFMCW fuzes.(2)Aiming at SMSP jamming,support vector machine(SVM)was applied.A power spectrum statistic for the input of SVM classification features was proposed for the disadvantage that the waveform entropy feature quantity did not have weak noise sensitivity,and then the average accuracy of the training samples was improved to 99.6364% by SVM polynomial kernel function parameter search.An FPGA implementation framework for SVM on LFMCW fuzes was designed based on the improved fixed-point SVM decision formulation,and the hardware implementation of this algorithm module was carried out on a Xilinx xc7a100tfgg484 chip via Verilog HDL language.The implementation results showed that the SVM-based jamming identification module was applicable to various modulation frequencies and reduced the resource usage of LUTs by 34% compared to the unimproved formulation.(3)Aiming at the suppression effect of SMSP jamming,a SMSP jamming suppression algorithm combining time-frequency domain transform and binary mask time-frequency domain filter was proposed,and the simulation showed that the algorithm can achieve effective jamming filtering in the case of SMSP jamming slices with n≤10 and JSR≤40dB.The hardware implementation of the jamming suppression algorithm module was carried out on the xc7a100tfgg484 chip using Verilog HDL language.In order to reduce the high resource overhead of the STFT module,a partially computed DFT module was designed in combination with the LFMCW fuze with a certain bandwidth.The implementation results showed that this module reduces the resource usage of LUTs by 47% without affecting the functionality.(4)A semi-physical simulation system of the IF anti-jamming algorithm module of the LFMCW fuze was designed for testing the IF-injected anti-jamming algorithm module.The joint hardware and software test was conducted,and the test results were consistent with the previous simulation results,which verifies the effectiveness and real-time of the jamming identification module as well as the jamming suppression module.