| As a stable,reliable and effective means of communication,communication satellites are playing an in-creasingly important role in the information field.However,since jamming stations located on a considerable territory of the earth can use satellite transponder receivers to transmit signals,The earth-spacecraft radio links of satellite communication systems are particularly susceptible to interference.Interference causes serious security problems in satellite communications.Aiming at the interference problem in the satellite mobile communication system,this paper conducts the following research:First,study the interference detection technology.Interference detection technology includes detecting the presence of interference and determining the frequency of the interference signal.A simple and efficient energy detection method is introduced to detect the existence of interference,and a signal projection-based interference existence detection method is proposed.Compared with the energy detection algorithm which can only detect the existence of interference,this algorithm can not only detect the existence of interference,but also obtain the power of the interference signal.Then analyze the frequency spectrum of the interfered signal.By using the frequency point detection algorithm to perform interference detection on each frequency point of the signal spectrum,the bandwidth of the interference signal can be obtained.This article introduces three kinds of interference frequency detection algorithms,and simulates and analyzes these algorithms.Next,study the estimation of the direction of arrival of the interference.This paper uses spatial spectrum estimation direction technology to estimate the interference signal DOA,so the basic knowledge related to array signal processing is first introducted,and then the interference DOA estimation algorithm is researched.Three classic DOA estimation algorithms are introduced,namely the MVDR beamforming algorithm,the MUSIC algorithm and the ESPRIT algorithm.Aiming at the high complexity of the MVDR algorithm and the MUSIC algorithm,and for specific satellite interference scenarios,a new DFT-based interference direction finding method is proposed on the basis of the MVDR algorithm and the MUSIC algorithm.Finally,the interference direction finding algorithm is simulated.Simulation shows that the proposed method has higher angle estimation resolution and lower complexity.Finally,the space-based Anti-jamming technology is researched by using the direction of the interference signal obtained by the interference direction finding algorithm.The criterion and performance index of the airdomain Anti-jamming algorithm are briefly introduced,and then the airdomain Anti-jamming algorithm is studied by using the estimated direction angle of the interference signal.The adaptive Anti-jamming algorithm,including the LCMV algorithm,LMS algorithm and RLS algorithm,is specifically explained.Aiming at the interference scenarios studied in this paper,these algorithms cannot directly obtain the desired signal,and the algorithm needs to be detected,so the complexity is high.Therefore,a new Anti-jamming detection algorithm is proposed,which can perform interference suppression and detection at the same time,and simulation experiments show that the detection performance of this algorithm is better than the MMSE algorithm. |
