Research And Realization Of Adaptive Nulling Anti-jamming Algorithm For Satellite Navigation

Global satellite navigation system can provide users with real-time and high-precision coordinate location,speed and time and other important information for twenty-four hours a day.It combined with a number of disciplines,which is widely used in the transportation,mapping,marine fisheries,disaster relief,precision timing,national security and other military applications.At present,all countries around the world regard it as a key development area,which is of great significance.Due to the fragility of satellite signals,navigation receivers are sensitive to various intentional and unintentional disturbances.Therefore,how to improve the anti-jamming performance of satellite navigation receivers is a key problem that needs to be solved urgently.In this thesis,the design method of adaptive anti-jamming algorithm based on array antenna is studied for the anti-jamming problem of satellite navigation and receiving system.The main work of the thesis is as follows:Firstly,it introduces the background of the research and the significance and importance of studying the anti-jamming technology of satellite navigation.It introduces the current international satellite navigation interference technology and anti-jamming technology,and analyzes the adaptive adjustment represented by airspace and space-time filtering Zero antenna anti-jamming technology development status,introduced the composition and characteristics of GPS signals,and the common suppression of the interference signal for a mathematical analysis.Secondly,through the understanding of the optimization criterion and the adaptive filtering of the airspace,the structure of the antenna array is analyzed and compared.Then,based on the linear constrained minimum variance and the minimum mean square error,the power inversion algorithm is compared via simulation.According to the theoretical analysis and simulation results,the pure airspace filter anti-jamming algorithm can only distinguish the direction of the interference signal,if the same with the navigation signal,the suppression effect is poor.Aiming at the problem of limited freedom,the space-time adaptive filtering method is studied.Then,the influence of the number of elements and delay taps in the space-time adaptive anti-jamming method is analyzed.It is verified that the degree of freedom of the space-time joint anti-jamming algorithm is higher than that of the power inversion algorithm,the adaptive anti-jamming effect of which is better.Finally,the design and engineering realization of the adaptive zero anti-jamming system are carried out.The design scheme of the anti-jamming algorithm is designed and implemented.The digital down-conversion pre-processing module is designed with FPGA as the hardware platform.Combined with the development process of FPGA and its characteristics,the algorithm is divided into several modules.The system function is achieved in the FPGA.The simulation results show that the proposed scheme can effectively suppress the narrowband and wideband interference,and verify the correctness of the algorithm.