Research On Robust Space-time Anti-jamming Algorithm For Beidou Receiver

With the speeding up of the construction of Beidou Navigation System,it plays much more important role in the national defense construction,social and economic development,etc.However restricted by satellite transmission power and satellite signal transmission distance,the satellite signal is very weak when it is received by navigation receiver,and it is easily affected by kinds of interference,which leads to degraded satellite communication quality.It is necessary to improve the anti-interference ability of Beidou Navigation System.This paper researches the anti-interference method of the Beidou Navigation System by adaptive array processing technology.First,introduces the traditional space-domain based anti-jamming algorithm,and improves the space-domain based algorithm using the uniqueness of navigation anti-jamming system.Based on the improvement,this paper applies space-time structure in the improved algorithm,through the theoretical simulation and actual environment test,it verifies the effectiveness of the algorithm.The contents are as follows:Firstly,introduces the Beidou Navigation System-work and Beidou signal model,and establishes the mathematical model of common jamming signals.On this basis,we analyze the effect of jamming signal.Based on the excellent performance of array antenna in the aspect of anti-jamming,this paper establishes the mathematical model of array antenna,analyzes static pattern of array antenna and introduces three optimization principles of anti-jamming algorithm.Secondly,according to the characteristics of the small satellite signal power,the power inversion algorithm is applied in Beidou anti-interference processing in this paper.Traditional power inversion algorithm has excellent performance,however,in practical application,it has high computational complexity and the best convergence factor of the algorithm is not fixed.In order to solve these problems,we improves the traditional power inversion algorithm by increase the normalized modules in the algorithm.The new algorithm uses the iterative calculation method,which reduces the computational complexity of the algorithm.In addition,the proposed algorithm normalizes the signal power in the process of iterative calculation,which ensure that the convergence factor of the algorithm is in the best state,and it improves the convergence speed and robust of the algorithm.Thirdly,on the basis of the research of the space domain-based anti-jamming algorithm,this paper applies space-time structure on navigation anti-jamming processing,the space-time structure increases the degree of freedom of the algorithm,improves the performance of the algorithm on the broadband interference.On the basis of the the theory simulation,in order to verify the anti-jamming performance of the algorithm in the real environment,this paper presents the FPGA implementation scheme of the algorithm to realize it in the hardware.Through the test in the real environment,it proves that the algorithm designed in this paper has a excellent anti-interference ability.Finally,studies the influence of high dynamic environment on the anti-interference ability of the algorithm.In the environment of high dynamic,due to the problem of time delay,the speed of the algorithm slower than the change of the jamming signal's direction,the performance of the algorithm was severely weakened.In order to solve this problem,this paper studies the two widely used high dynamic compensation algorithm: differential constraint algorithm and virtual interference algorithm.The two algorithm has a excellent performance on dynamic compensation,but under the condition of small snapshot,the algorithm is affected by noise seriously,for this,this paper improves the algorithm by modify covariance matrix of the signal,reduce the influence of noise on algorithm under the condition of small snapshot,improves the dynamic performance of the algorithm.