Research On Anti-jamming Waveform Design Of Missile-borne Radar

With the increasingly complex electromagnetic environment,the electronic countermeasures are also complicated and diversified.The traditional anti-jamming technology can not meet the current operational needs,and effective anti-jamming technology needs to be studied.Under this background,this paper studies the countermeasures of narrow-band suppression interference,repeater jamming and smart jamming.The main work is as follows:For the narrow-band suppression interference,it can be effectively countered by the frequency agility technology,but the frequency agile signal has the problem of poor side-lobe performance.Therefore,this paper focuses on the optimization design of the low-sidelobe frequency agile signal.By analyzing the fuzzy function of the frequency agile signal,the sidelob level of range ambiguity function is determined by the frequency group and the signal intrapulse modulation,while the Doppler sidelobe level is determined by the frequency group.Therefore,an optimal design method for intrapulse phase-encoding inter-pulse frequency agile signals is presented.The optimization design of this signal is mainly divided into two steps.The first step is to optimize the signal frequency group to improve the Doppler sidelobe level.But only by optimizing the frequency combination,the optimization of the Doppler sidelobe optimization is limited.For this reason,a joint optimization design method of frequency combination and mismatch filter is proposed in this paper.Since this joint optimization problem is non-convex,this paper solves it by alternating iterative algorithm.In the second step,the intrapulse phase code is optimized to improve the sidelobe level of the range ambiguity function.The minimum of peak sidelobe level served as the optimization criterion,which is solved by the adaptive gradient algorithm.The simulation results show that the proposed method is effective.For the repeater jamming and using the characteristics that the interference has a certain pulse period delay,this paper combines the inter-pulse diversity technique to achieve the effective confrontation of this interference.The most direct and effective countermeasure is to orthogonalize several signals transmitted by adjacent ones.Therefore,this paper first studies the optimization design of quadrature phase encoded signals.For this signal,the orthogonality between signals and the autocorrelation performance of the signal itself should be considered simultaneously.Therefore,the minimum of weighted sum of the autocorrelation peak sidelobe and cross-correlation peak of the signal is served as the optimization problem.This problem is solved by genetic algorithm,and the relationship between waveform parameters and waveform optimization results is further analyzed through simulation experiments.Aiming at the problem that the orthogonal performance of phase-encoding waveform is limited,this paper further gives a design method of adaptive inter-pulse phase-encoding signal.By adaptively optimization design of the interpulse phase codes,the interference energy can be distributed outside the target detection area.The simulation results show that the proposed method can effectively suppress the repeater jamming.For smart interference,it has both briquettability and deception,and it is not ideal or even invalid through the inter-pulse agile technique.This paper proposes an adaptive space-time phase coding optimization design method based on MIMO technology.The interference energy can be distributed outside the target airspace detection area,thereby achieving anti-interference.However,since this method will gradually fail in the presence of smart interference with different pulse delay periods,this paper further proposes an interference cancellation processing method based on space-time phase-encoded signal.The “clean” interference samples can be obtained by canceling the echoes of the space-time phase-encoded signal and coherent MIMO signal,which is used for interference cancellation processing,thereby achieving interference suppression.The simulation results show that the proposed method can effectively suppress the smart interference.