Research On The Interference Suppression Of Bei Dou Space Time Adaptive Subspace Projection Method

BeiDou satellite navigation system as an important strategic resources in our nation's military application,it will inevitably face the interference of various jamming equipment in the future application.Anti-jamming technology research for BeiDou navigation system has a very important strategic significant to improve the national defense construction and military strength.Array signal processing is one of the most important methods in the field of satellite navigation anti-jamming,the technology of space-time array processing has a higher degree of freedom and anti-jamming ability than the single space and time domain processing.The subspace orthogonal projection method is used to project the received signal to the interference orthogonal complement space,theoretically,the interference can be completely filtered out while the beam is formed in the direction of the desired signal,but the orthogonal projection also weakens the desired signal.The subspace oblique projection method can be used to project the signal into the signal subspace,which completely removes the interference while preserving most of the desired signal,and improves the output signal-to-interference-noise ratio of the array,further enhances the ability of space-time adaptive anti-jamming.The traditional space-time subspace projection method uses the received data covariance matrix singular value decomposition to estimate the subspace,and the computational cost is large.To solve this problem,this paper adopts multistage Wiener filter to estimate the subspace,which reduces the computational complexity of space-time interference subspace projection method.In addition,an improved multistage Wiener filter subspace estimation method is proposed in this paper,which makes the computation time of subspace projection algorithm can be further can be further reduced and improves the ability of real time anti-interference of space-time array.The main contents of this paper are as follows:(1)Introduced and studied the basic content of anti-jamming in BeiDou navigation environment.Introduced the structural characteristics of BeiDou signal,emphasis on the simulation analysis of BeiDou ranging code and QPSK modulation mode.Established the narrow-band and wide-band interference signal model and the interference is simulated.In the part of the anti-jamming technology,the basic principle of array signal processing and the optimal weight criterion of adaptive array are introduced.(2)Studied the performance of BeiDou space-time adaptive anti-jamming.Introduced the space-time adaptive anti-jamming array processing structure and its basic principles,summarizes and simulates and analysis the commonly used adaptive filtering algorithms.Analyzes the influence of the freedom of the space-time array on the anti-jamming performance.The optimal beam forming algorithm based on linearly constrained minimum variance criterion is used to simulate the performance of space-time arrays with different number of delay elements,different array elements and different sampling snapshots.(3)The anti-interference method of BeiDou space-time adaptive subspace projection is studied in detail,including anti-interference method of space-time subspace orthogonal projection and space-time subspace oblique projection.And compares with the optimal beam forming method and power inversion method.The array output signal to interference noise ratio relationship with input SNR,tapped delay line number,the number of array elements,the number of sampling snapshots are discussed,the anti-jamming performance of subspace projection space-time array in the presence of angle mismatch is considered.(4)Aiming at the problem that traditional space-time anti-jamming subspace projection method is computationally expensive,space-time dimension reduction processing model and multistage Wiener filtering method are studied.The multistage Wiener filter is applied to the subspace estimation of space-time subspace projection interference.The comparison of the space-time subspace orthogonal projection and oblique projection method based on multistage Wiener filtering and eigenvalue decomposition based on received data covariance matrix are given respectively.In this paper,we propose an improved multistage Wiener filter algorithm,the space-time subspace projection method based on improved multistage Wiener filter and the space-time subspace projection based on original multistage Wiener filtering are compared and simulated respectively.The research on the anti-jamming technology of BeiDou navigation system is in line with the requirements of the times,the research of this paper enriches the achievements in the research of BeiDou anti-jamming,it can be used as a reference for the study of the anti-jamming performance of BeiDou space-time subspace and the anti-jamming performance of BeiDou space-time array.