Research On Anti-jamming Key Technologiesof Digital Array Radar

Modern radar is faced with complex and changeable jamming environment.How to achieve effective anti-jamming to ensure radar system performance is an important challenge.This thesis carried out the research on anti-jamming technology for digital array radar.First of all,for the multi-dimensional characteristics of the interference in space /time / frequency domain,a characteristic parameter set of typical interference is established,and a comprehensive classification / recognition method of interference patterns is given.Then,the theoretical analysis and engineering application research of active anti-interference technology were carried out from three levels,including the optimization of anti-interference algorithms,the optimization design of complex waveforms,and the realization of anti-interference hardware circuits.The research contents of this article include the following five aspects:1 Intelligent identification of interference based on multi-dimensional featuresReal-time and accurate interference pattern identification is the core technical for interference countermeasures such as hierarchical interference suppression and dynamic configuration of complex waveforms.In view of this,this thesis abstracts multi-dimensional feature parameter sets such as time,frequency,time-frequency for typical interference patterns,and presents a dual-channel interference pattern recognition method based on decision trees,which combing wide-band and narrow-band detection channel,and interference pattern recognition method of convolutional neural network based on phase time-varying features,respectively.From the perspective of interference pattern recognition,the research results of this thesis realized high-confidence extraction of interference features and classification of interference patterns.In addition,the content in this section will provide basic technical support for optimizing anti-jamming game strategy configuration.Simulation experiments prove the effectiveness of the two interference pattern recognition methods proposed in this thesis.2 Robust estimation of DOA for plane array interferenceIn view of the main problems existing in two dimention direction of arrival estimation,such as the high degree of freedom requirement,the low utilization of the array elements,matrix filling theory is introduced into 2D-DOA estimation of planar array,and a 2D-DOA estimation method based on the combination of accelerated proximal gradient(APG)algorithm and multiple signal classification(Music)method is proposed in this thesis.Firstly,the 2D-DOA estimation model is established by using sparse array to collect radiation source data,and it is proved that it has low rank characteristics and satisfies the null space property(NSP),which provides theoretical basis for using matrix filling method to complete missing data and reconstruct complete matrix.Secondly,a sparse sampling array optimization method based on Genetic Algorithm(GA)is studied.The method of off-line optimization of sampling array can improve the performance of reconstruction of array received signal matrix under sparse array,and improve the applicability of matrix filling method under different antenna configurations.Finally,APG method is used to reconstruct the received signal of sparse array to complete signal with high confidence,and music algorithm is used to complete 2D-DOA estimation.Compared with the conventional2D-DOA method,the proposed method greatly improves the utilization ratio of planar array elements,and only a few elements can be used to receive signals to achieve high-precision DOA estimation.3 Adaptive sidelobe cancellation under main lobe interferenceIn order to adapt to the complex electromagnetic environment where the main and side lobe interfere existing simulation,this thesis adopts the idea of differential sidelobe cancellation for linear arrays proposing multiple subtraction multiple side-lobe canceller(MSLC)and feedback subtraction side-lobe canceller(FS-MSLC)algorithm,respectively.Compared with the general side-lobe canceller,the proposed methods eliminate the influence of the main lobe signal,realize the effective suppression with keeping the main lobe pattern undistorted when there is the main lobe incident signal.The simulation results show the effectiveness of the algorithm.4 Optimized design of complex waveforms for active anti-interferenceFirst,in order to reduce the impact of the deception jammer on radar detection,the strategy of the shielding waveform is given,and the advantages and disadvantages of the proposed strategy are analyzed.Secondly,in order to improve the ability of digital array radar against to deception jamming,an agile phase-coded pulse train signal design method with low sidelobe ambiguity function in the target area is proposed.The simulation results show that the pulse train optimized by SVD decomposition improves the quality of target information under strong confrontation environment and enhances the applicability and practicability in complex and variable electromagnetic environment.Then,for speed deception jammer,an optimization criterion for minimizing the Doppler region where the false target is located is proposed,and the initial phase of the coherent waveform is optimized.The simulation results show that the proposed method can effectively suppress the speed gate where the false target is dragged,and the nearby energy significantly improves the signal-to-noise ratio in the energy notch.Finally,from the aspects of interception factor and recognition difficulty for jammer,the evaluation and verification criteria for the anti-reconnaissance performance of complex waveforms are proposed,which further provides engineering basis for waveform design optimization and precise use.5 Key technologies of phased array radar active anti-jamming hardwareIn order to drive the engineering application process of digital array radar time/frequency/waveform joint active anti-active interference technology,this thesis proposes two methods for implementing Digital Pulse Width Modulation(DPWM)based on commercial digital control circuits.The research results of this thesis significantly expands the application scope of commercial digital control circuits in the field of radar-electronic warfare,provides basic support and low-cost solutions for building active anti jamming systems.Experimental results show that the delay accuracy of the two methods proposed in this thesis reaches 625 ps and 500 ps,respectively,and the pulse width stability reaches 50 ps,which proves the effectiveness and practicability of the method.