Research On Key Techniques Of Anti-Interference Satellite Navigation Receiver

Satellite navigation system is widely used in the area of highway, railway, maritime navigation, telecommunication, petroleum exploration, construction, agriculture, meteorology, hydraulics, environmental protection, oceanography, estate administration, fishing industry, geological prospecting, geodetic surveying, tourism, finance, public security, fire protection, etc, and in the area of spacecraft, space station docking, shooting range monitoring, aviation, military reconnaissance, field single soldier battle system, intelligent weapon, dexterity bomb, etc as well, since it can provide high accuracy positioning and timing with the navigation characteristic of 24-hour service, real time, continuity and passivity. Nevertheless, satellite navigation signals are so weak that they are susceptible to kinds of interferences in face with complicated channel environment of weak satellite signal and strong interferences. As a result, the satellite navigation system is susceptible to both the intentional and unintentional interferences, including jamming and spoofing. When there come jamming interferences, jamming signal cover the whole frequency spectrum of the satellite signal, and greatly reduce the signal to noise ratio, with the result that the navigation accuracy of position and velocity decrease seriously, and the navigation receiver is unable to capture and track the satellite signal in most cases. When there come spoofing interferences, the navigation solution deviates from the truth, and since the receiver is unable to perceive the deviation, the spoofing interferences bring about great calamity. Therefore, this dissertation research on several key techniques in the satellite navigation anti-interference (including jamming and spoofing interferences) receiver with respect to the fact that the satellite navigation system is vulnerable to the interferences, the jamming interferences lead to the low accuracy of navigation solution for normal operation, and the spoofing interferences lead to the deviation of navigation solution from the truth, while the receiver is unsuspicious.Firstly, Research on anti-jamming adaptive filter for the satellite navigation receiver. When there exist multiple jamming interferences (including broadband and narrowband), the accuracy of the navigation solution decreased below the normal level. Since the jamming signals cover the whole frequency spectrum of the navigation signals, traditional anti-jamming algorithm using the adaptive antenna array or space time adaptive processing algorithm. Nevertheless, as the jamming signal is greatly suppressed, the satellite signal which has similar direction of arrival with jamming is depressed simultaneously, and thus depresses the system performance with limited visible satellites. Therefore, this dissertation proposes improved space time adaptive processing algorithm with direction restriction obtained from the direction detection and estimation of the jamming and the satellite information. The algorithm has the characteristics of high degree of interference suppression and high degree of freedom (amount of interferences suppressed simultaneously), especially when the satellite signal and jamming has similar direction, the satellite signal could be received normally, while the jamming is suppressed greatly. Simulation suggests that the jamming signal is suppressed more than 40 dB, and the degree of freedom is increased with finite antenna array scale, especially when the satellite signal and the jamming signal have similar direction of less than 10°, the receiver is able to operate normally while the jamming signal is depressed, which is profitable when the satellite navigation system is built at preliminary stage and the visible satellite is limited.Secondly, Design of anti-spoofing processing for satellite navigation receiver, including two aspects: spoofing signal characteristics discrimination method research and anti-spoofing navigation solution research. First of all, discriminate the spoofing signals with concern of the characteristics of spoofing signals. And then propose an improved extended Kalman filter algorithm in the navigation solution process for the high quality spoofing signals which can not been discriminated. The proposed improved anti-spoofing extended Kalman filter algorithm make use of the M-estimator of robust statistics, and adapt the innovation process of extended Kalman filter with the simplified weighted factor produced in the M-estimator, which reduces the computational complexity while maintaining the accuracy of the navigation solution and improve the anti-spoofing performance of receiver, and thus is beneficial to the realization of the algorithm in the project. Simulation suggests that in comparison with the conventional snapshot least square algorithm and the conventional extended Kalman filter, the proposed anti-spoofing extended Kalman filter is able to reduce the deviation of the navigation solution caused by the spoofing signals (the pseudorange measurement error caused by spoofing signal is 1200m) with higher navigation solution accuracy with position precision is above 10m and velocity precision is above 0.5m/s (GPS as example), and less computational complexity.Thirdly, improvement design of satellite navigation receiver with the ability of anti-interference. In comparison with traditional satellite navigation receiver, the paper proposes an improved design of satellite navigation receiver with the ability of anti-jamming and anti-spoofing, and also proposes the designs of both the medial frequency signal processing and the information processing, including the anti-jamming module, the anti-spoofing module and the satellite signal capture and tracking module. Simulations compare the traditional satellite navigation receiver with the proposed anti-interference receiver in the aspect of signal to noise ratio of anti-jamming signal processing module, performance of satellite signal capture and tracking module, and navigation position and velocity solution accuracy of anti-spoofing module, which suggests that the anti-interference (including jamming and spoofing) receiver proposed is able to effectively suppress jamming and spoofing signals, credibly capture and track satellite signals and have higher accuracy of navigation solution in position and velocity, which indicates that the proposed anti-interference receiver is provided with certain capability of anti-jamming and anti-spfooing.