Research On Satellite Navigation Terminal Based On Space Time Adaptive Processing Technology

The anti-jamming technology is introduced into the satellite navigation system to solve the problem that the receiver is seriously affected by the interference signal due to the low signal-to-noise ratio of the satellite navigation signal.At present,the most widely used anti-jamming technology is Space-time Adaptive Processing(STAP)technology which of the degree of freedom is higher than the space anti-jamming or the time anti-jamming technology.STAP technology extends space from one-dimensional to two dimensional,greatly reducing the area of antenna arrays,and can anti both wideband and narrowband interference.However,the anti-jamming research of satellite navigation system mainly focus on GPS navigation system,and the anti-jamming research about Beidou satellite navigation system is still in the initial stage.In this paper,the anti-jamming research of Beidou navigation system is based on STAP algorithm to change covariance matrix structure and combine heuristic optimization algorithm,which is verified whether is feasible or not.The main work of this paper is as follows:1.In the first stage,introduce the fundamental principle of STAP anti-jamming technology,the mathematical model of Signal-to-Interference plus Noise Ratio(SINR),the interference type and the antenna array type of the receiver based on some problems of the receiver of navigation system,including the low signal-to-noise ratio and the interference signal to affect receiver during receiving signals.The advantages and disadvantages of optimal constraint criterions such as Linearly Constrained Minimum Variance(LCMV),Maximum Signal to Interference and Noise Ratio(MSINR)and Minimum Mean-square Error(MMSE)are described and analyzed.The simulation results shows that the STAP algorithm based on LCMV criterion is the best one to anti-jamming.2.In the second stage,this paper researches two anti-interference performance indicators,including the SINR improvement and the beamforming.Based on the covariance matrix structure of STAP,we propose Correlation Subspace Projection(CSP)based on Covariance Matrix Estimation algorithm to improve the SINR improvement of STAP.And CSP algorithm compares with Eigen-space Based algorithm,Interference Subspace Projection algorithm,Rank Constrained Maximum Likelihood algorithm and Training-based Data algorithm.Then Multi-linear Constrained algorithm combines with some comparison algorithms to solve beamforming questions of STAP,which compares with CSP algorithm.And simulation results indicate that the method can increase the SINR improvement and ensure a good beamforming result.3.In the last stage,STAP algorithm combines Firefly Algorithm,Cuckoo Search algorithm and Bat Algorithm,which increases the SINR improvement of STAP.To compare calculation time of three optimization algorithms,it shows that BA algorithm,the best algorithm of three,can improve the SINR results and use the least time.Then,STAP algorithm based on covariance matrix structure optimization combines these heuristic optimization algorithms to improve beamforming results,comparing Ant Colony Optimization algorithm and Wind Driven Optimization algorithm.To improve the global optimization problem of bat algorithm,a new bat algorithm based on covariance matrix adaptation evolution strategy is proposed,which combines with STAP algorithm to improve the SINR improvement and beamforming results.The simulation verifies that heuristic optimization algorithms can improve SINR and beamforming of STAP.