Research On Combined Gps/glonass Single-point Positioning And Raim

This dissertation first focus on the principle and methods of positioning by GPS and combined GPS/GLONASS respectively, and then studies the algorithms of receiver autonomous integrity monitoring. Based on the introduction of the concerned theories, this dissertation analyzes real observation data and simulates some merits. The main works are summarized as follows:1. The general knowledge of Global Positioning System, the basic principles of GPS point positioning using pseudo-rang measurements and the GPS absolute velocity determination using Doppler measurements are introduced. Some merits of processing precise ephemeris in precise point positioning are analyzed. Some high accuracy error correction models are introduced. The sequential least squares estimation with eliminating parameter merit is deduced. The research way to enhance point positioning accuracy is indicated. Some methods are carried out by programming. Some conclusions are gotten by analyzing experiments. These conclusions have meanings to practice.2. The general situation of GLONASS is introduced. The differences between GPS and GLONASS positioning are analyzed in detail. Ephemeris computing methods are studied. The point positioning method using combined GPS and GLONASS is studied. Helmert variance component estimation is used to determinate the weights for two kinds of observations reasonably and improve the positioning accuracy. By computing and analyzing real experiments, some meaningful conclusions are obtained.3. Some basic concepts of RAIM are introduced. Different methods of justifying RAIM availability are compared. Using GPS and GLONASS broadcast ephemeris, the constellations are simulated to analyze the RAIM availability of GPS alone or hybrid GPS/GLONASS. RAIM holes are drawn, which provides a visual measure to predict RAIM availability.4. The theory on detection of gross errors by residuals is introduced, which is the foundation of understanding RAIM fault detection and exclusion methods. Some conventional"snapshot"algorithms are introduced, and the application problem of"Quasi-Accurate Detection of gross errors"method in RAIM is studied. By simulating different fault types and different RAIM algorithms, some valuable conclusions can be drawn5. The classical Kalman filter theory is introduced. The properties of innovation vector are studied in detail. The problem of using innovation vector in RAIM fault detection algorithm is studied. Simulation results demonstrate that the method is feasible.