Research On Anti-jamming Technology In Satellite Navigation System

Currently,satellite navigation system is widely used in quite diverse domains,it is an important national infrastructure.It not only represents the scientific and technological strength of a country,but also embodies a great power status of national and comprehensive national.However,satellite navigation signal is very weak when arriving at satellite receivers,causing satellite navigation signal to be susceptible to electromagnetic radiation or even human interference in the environment.This requires that the anti-interference performance of the satellite navigation system must be improved,so it is necessary to study the anti-interference technology of the satellite navigation system.Based on the background,this paper studies how the receivers of satellite navigation system suppress the interference in the complex external environment and improves the anti-interference performance of the system.The main contents are as follows:(1)The anti-interference methods commonly used in satellite navigation systems are introduced,including their principle,structure and characteristics,etc.It is pointed out that the space-time and space-frequency joint domain anti-interference method can distinguish interference signals from more dimensions,and with better anti-interference performance.The algorithms and criteria used in the anti-interference method are discussed.(2)The spatial SMI(Sampling Matrix Inversion)and RLS(Recursive Least Squares)algorithms,space-time SMI and RLS algorithms,and space-frequency SMI and RLS algorithms are studied under the maximum signal-to-noise ratio criterion,and the corresponding algebraic formulas are derived,and the performance of the algorithm are simulated.The results show that the anti-interference performance of SMI algorithm is better than RLS algorithm in general.The space-time and space-frequency anti-interference algorithm can improve the degree of freedom of the array and can distinguish the interference signal on the frequency.When the expected signal and the interference signal are very closed in space,the performance of these algorithms will drop by more than 10 d B.(3)In view of the fact that the anti-interference performance of the above algorithms declines when the expected signal and the interference signal are close to each other in space,the concept of spatial correlation coefficient is introduced.The relationship between it and the output signal-to-noise ratio and system performance has been analyzed.The larger the spatial correlation coefficient is,the smaller the output signal-to-noise ratio is,and the worse the anti-interference performance of the system is.The smaller the spatial correlation coefficient is,the larger the output signal-to-noise ratio is,and the better the anti-interference performance of the system is.According to this relationship,the concept of the optimal direction is proposed,and the expressions of the optimal direction and spatial correlation coefficient under different antenna arrays are derived.The relationships between the spatial correlation coefficient and the array steering angle under the condition of different antenna configuration,different number of array elements and different desired signal pitch angle are simulated.Meanwhile,the anti-interference method for satellite navigation system is proposed.By changing the structure of the antenna array,it is turned to the optimal direction,the value of the spatial correlation coefficient is optimized,and the output signal-to-noise ratio of the system is improved,thereby improving the anti-interference performance of the system.Thereby improving the anti-interference performance of the system,and by simulation,the output signal-to-noise ratio can be increased by up to 46.68 d B in the case of a uniform line array.