Research And Implement Of Positioning Algorithm In GNSS Receiver

GNSS, i.e. Global Navigation Satellite System, uses one or several of American GPS, Russian GLONASS, European GAILILEO and China's BD system to provide navigation and location services, and provides satellite integrity checking and navigation safety alarm information. This thesis mainly studies positioning algorithm and its realization.Generally speaking, GNSS receiver location resolution module is the process of utilizing more than four satellites' location and speed, and the pseudorange of the user as input to calculate the user's location and speed at some time. Firstly this thesis introduced the four satellite navigation systems, and then introduced the components of GNSS receiver and the location theory, and after these simply introduced the modules such as capture module, tracking module and synchronization module. Based on these, this thesis designed the hardware and software architectures of the receiver, in which the thesis described the software configuration and designed the flow chart of the general module and every sub-module. This article assessed the results in the various scenarios using C language based on VS2005, and using the least-squares iteration method and the Kalman filter method to positioning; more emphases are placed on the simulation and evaluation of parsing navigation ephemeris, satellite positions and velocities, tropospheric and ionospheric model and PVT. And the positioning results are analyzed and drew using matlab, Simulation results show that the algorithm can satisfy the performance. and then the positioning algorithms are migrated to Visual DSP + + integrated development environment for test. In the process of testing, this thesis adopted a nonlinear tracking differentiator to support carrier-phase velocity, it improved the speed accuracy greatly. Finally the article analysed and corrected the key factors affecting the positioning accuracy, and realized the RAIM algorithm to monitor the state of satellites to improve positioning accuracy. Test results show that the receiver works well for the test system, the parameters and indicators of the positioning meet the requirement of field test for GNSS receiver product.