Research And Implementation Of Positioning Algorithm For The Fusing Of BDS/GPS Data

Positioning module is the top module of the satellite navigation receiver, whose performance determines the navigation and positioning precision directly. Today, there are more than one satellite navigation and positioning system. How to fuse datas from different system to improve the precision of navigation and positioning is one of the hot spot of current research in the area. Therefore, the research and implementation of positioning algorithm for the fusing of BDS and GPS datas is very important and useful.In terms of positioning algorithm, how to improve the kalman filter is mainly studied. Aiming at the problem of single model appearing large deviation under the condition of rapid turn and the large computation of interactive multiple model system in satellite navigation and positioning, a fast IMM algorithm is proposed. The Current Statistics model is improved. Then the Constant Velocity model and the improved CS model are used to form a multiple model system. Based on the modified filter divergence criterion and the subprime maximum a posteriori estimation, the motion model of kalman filter is changed automatically according to the actual movement of carrier. In this way, the shortcoming of single model in describing the complex movement is improved. The simulation results show that the algorithm improves the positioning accuracy of different motion state, and reduces the computation at the same time.In terms of BDS and GPS datas fusion processing, the unity of time and space benchmark and the algorithm of choosing stars are studied. In order to solve the problem of heavy computation and bad real-time performance, a fast stars choosing algorithm is proposed. Based on the satellite’s elevation and azimuth information and the principle of maximum volume method, the algorithm chooses suboptimal stars combination very quickly. The pseudorange single point positioning model of BDS and GPS datas fusing is built, and is tested systematically. The simulation results show that the precision of the pseudorange single point positioning after BDS and GPS datas fusing is higher than single syetem, especially when GPS observation condition is bad. Fusion pseudorange single point positioning can reduce reliance on single system, and can enhance the reliability and availability of satellite positioning. And then, based on STM32 platform, the software of GPS positioning computation algorithm is designed. The test results show that the software can process GPS navigation message effectively, and can figure out the 3d coordinate information of user’s location.