Research On Navigation And Positioning Performance Evaluation For GNSS Full Constellation And Its Validatation

With Beidou-3 fully completed and put into use,there are four global navigation and positioning systems in the world: the US GPS satellite navigation system,Russia's GLONASS satellite navigation system,the European Union's Galileo satellite navigation system and China's Beidou satellite navigation system,including Japan's quasi-zenith satellite system QZSS and Indian navigation system IRNSS regional system,as well as satellite-based augmentation system SBAS,ground-based augmentation system.With the continuous improvement and development of the GNSS system,how to evaluate the navigation and positioning performance of the GNSS system more comprehensively has become a research hotspot,especially in the polar regions,low and middle latitude regions,mountainous areas and urban canyons where the coverage of GNSS satellites is not high.The evaluation of GNSS navigation and positioning performance under the conditions of GNSS needs to be explored.Based on the knowledge of GNSS time system,coordinate system,satellite data calculation,data quality assessment,etc,and using MATLAB as a data processing and visualization platform as a software development platform,this thesis designs a GNSS full constellation navigation and positioning performance evaluation simulation platform.Realize the simulation of different areas,terrains,and complex environments,and analyze the navigation and positioning performance combined with satellite trajectories.Finally,the navigation and positioning performance evaluation simulation platform is used to compare and analyze the simulation and measured data,which not only verifies the effectiveness of the developed simulation platform,but also analyzes and evaluates the GNSS constellation in the global scope,regional scope and considering the actual terrain factors.Navigation and positioning performance,the main tasks completed are:(1)The recent development status of each GNSS system is analyzed,and the comparative analysis between GNSS systems is given,focusing on the difference of the space-time reference between systems,providing a theoretical basis for the following unification of space-time standards,and combining with GNSS The research status of system navigation and positioning performance further clarifies the main research content of this thesis.(2)Navigation and positioning performance indicators such as precision factor calculation,service availability and data quality assessment of the GNSS system are expounded.Then,the basic space-time reference and coordinate system conversion relationship of GNSS combined application are introduced,and through programming,the mutual conversion between coordinate systems,ephemeris file parameter reading and storage,satellite position calculation and visible satellites are realized.Programs such as the calculation method of altitude and azimuth provide the basis for the realization of the simulation data module and the platform construction in the following.(3)The satellite trajectory simulation module in the geocentric and ground-fixed coordinate system and the sub-satellite point trajectory simulation module in the twodimensional plane are developed.Then the 3D model environment construction and the real 3D model construction are carried out to provide environmental factor constraints for the simulation data calculation,and the realization principle and method of the main evaluation indicators of the data quality evaluation module are given.Finally,combined with the above content,a GNSS navigation and positioning performance evaluation simulation platform is established,and the overall framework and main modules of the platform are given.(4)The GNSS full constellation navigation and positioning performance simulation platform is used to evaluate and measure the navigation and positioning performance in the unobstructed environment on a global scale and in the regional scope,and in the urban canyon,special buildings,forest roads and other complex environmental occlusion environments considering terrain factors.Data verification provides some feasible suggestions for actual surveying and mapping work.