Study On Suppression Of Mainlobe Deceptive Jammer With EPC-MIMO Radar Based On Polyphase Code

In the research of electronic counter-counter measures(ECCM),the suppression of mainlobe deceptive jammer is an important topic.Because the information of the jammer is similar to the echo of the real target,but the traditional phased array radar has limited degree of control freedom and less information dimension,it has limitations in suppression of mainlobe deceptive jammer.Element-Pulse Coding(EPC)MIMO radar is a new waveform diversity array radar proposed in recent years.The EPC framework carries out two-dimensional coding between different transmission channels and pulses.By combining the EPC framework with MIMO radar,a phase term related to the coding coefficient and the number of delayed pulses is added to the transmit steering vectors,so that the number of delayed pulses can be used to discriminate targets located in different range regions to achieve jammer suppression.The orthogonal waveform of MIMO radar can be obtained by a phase encoding signal.Polyphase codes has more phase combinations,more flexible selection of codewords,better self/cross correlation and improved the doppler tolerance.Therefore,this paper conducted a series of study on suppression of mainlobe deceptive jammer for EPCMIMO radar based on polyphase codes.The main contents of this thesis are as follows:1.EPC-MIMO radar signal model based on polyphase code was established.First,the polyphase codes used in the signal model and their related optimization algorithms are introduced.They are CAN algorithm optimized for single sequence and Multi-CAN algorithm optimized for multiple sequence.And the optimization results of the two algorithms are analyzed through simulation experiments.Next,the EPC-MIMO radar model is introduced.By comparing with FDA-MIMO radar,the range ambiguity resolution ability of EPC-MIMO radar is briefly analyzed.The EPC framework,the EPC-MIMO radar receiving signal model and the receiving signal processing flow are mainly introduced.2.Focused on the problem of jammer suppression performance of non-adaptive beamformer when false target has an angle estimation bias,the method of mainlobe deceptive jammer suppression in EPC-MIMO radar based on preset broadened nulling beamformer are studied.Firstly,the generation of mainlobe deceptive jammer and the method of distinguishing between true and false targets are analyzed.Based on this,the mainlobe deceptive jammer is suppressed by using a transmit-receive two-dimensional(2-D)non-adaptive beamformer,by selecting an appropriate coding coefficient so that the false target is located at the nulling of the EPC-MIMO radar equivalent transmission pattern.Next,the non-adaptive preset broadened nulling beamformer(PBN-BF)algorithm is introduced,which can effectively widen the nulling of the EPC-MIMO radar equivalent transmission pattern by artificially adding virtual interference.When there is an angle bias in the prior estimation,the false targets can also be effectively suppressed.This improves the jammer suppression performance of EPC-MIMO radar.3.A mainlobe deceptive jammer suppression method based on pulse domain in EPC-MIMO radar is proposed,and the measured data are processed and analyzed.Firstly,the information difference between the forwarding false target and the true target in EPC-MIMO radar is analyzed.The method proposed uses the information difference for subsequent antiinterference processing.Then,the EPC-MIMO radar field experiment system,the measured data acquisition environment and the transmission waveforms of the field experiment are introduced.Finally,the EPC-MIMO radar measured echo data is processed and analyzed with the method proposed.The results show that the orthogonality of the polyphase codes optimized by the Multi-CAN algorithm is good,and the proposed method can effectively extract the true target from the EPC-MIMO radar measured echo data,and achieve the suppression of mainlobe deceptive jammer.