Research On Beidou/GPS Integrated RAIM Algorithm

With the gradual development and improvement of satellite navigation systems in various countries,more and more abundant navigation satellite resources are available in space.Due to the significant increase in the number of navigation satellites and multi-frequency signals,the positioning performance and stability of the system are improved,and it is possible to apply the multi-satellite navigation systems to the higher flight phases in civil aviation flights.Receiver Autonomous Integrity Monitoring(RAIM)technology can detect faulty satellites in time and ensure the reliability of receiver positioning.Therefore,the specific research content of this thesis is as follows:The first part introduces the conversion of the BDS/GPS time system and the conversion of the BDS/GPS coordinate system.Based on the unity of space and time,the single-point positioning principle and positioning algorithm of the BDS/GPS combination are researched,and the dilution of precision is used to evaluate the combination of positioning accuracy.In the second part,aiming at the deficiency of the least-squares RAIM algorithm,the weighted least-squares RAIM algorithm is proposed,and the determination of the weighting factor is studied.At the same time,aiming at the detection and identification of multi-constellation and multi-faults and the availability of the algorithm in the vertical guided approach phase,the optimal weighted average solution algorithm is proposed,and the determination of the optimal weight factor is researched.The weighted least squares algorithm combined with the optimal weighted average solution algorithm are used to detect and identify the existence of a fault in each constellation of the double constellation.In the third part,aiming at the more conservative problem that the method of multiple hypothetical solution separation is used to calculate the vertical protection level,the method of dynamically assigning the probability of hazardously misleading information is proposed.Under the condition of ensuring the overall integrity index of the system,the user protection level will be reduced though this method,thereby improving system availability.At last,the research work of this thesis is summarized,and the content need to be improved is remarked in the future.The results of this study are of great significance to ensure the reliability of satellite navigation,and have a certain meaning that promote the application of satellite navigation to the approach flight of the aircraft.