Methodology Of Quality Control For GNSS Real-time Precise Point Positioning

With the acceleration of the modernization of Global Navigation Satellite System(GNSS)and GNSS real-time precise products,GNSS real-time precise point positioning(PPP)has become a current research hotspot.However,GNSS real-time PPP data processing methods face many challenges such as incomplete quality control,complex multi-system and multi-frequency processing,and high requirements for realtime processing.The thesis focuses on the above problems,based on the theory of data detection and robust estimation,to carry out the quality control method research of the whole process of real-time PPP data processing.At the same time,combined with the actual application of Beidou "One Belt One Road" high-precision location and time public service platform,a GNSS real-time PPP cloud computing system was designed and implemented.The main contributions and innovations are as follows:(1)The quality control method of GNSS real-time PPP is systematically studied.In order to achieve controllable quality throughout the process and ensure the reliability of positioning results,a complete GNSS real-time PPP quality control system has been designed.The quality control methods of real-time PPP input stage,processing stage and output stage are studied.(2)Optimized and improved the real-time quality control method of Multi-GNSS and Multi-frequency observation data in the real-time PPP input stage.In view of the scattered research on the current GNSS multi-system and multi-frequency real-time data processing research is relatively fragmented,the pertinence is not strong,etc.,and the research for the pseudorange gross error detection,cycle slip detection and repair,clock slip detection and repair algorithm in real-time mode from single frequency to quad frequency have been systematically carried out.Verify the feasibility of the analysis algorithm for GNSS/BDS3 through a large number of calculation examples.(3)Proposed and perfected the quality control method of GNSS real-time orbit and clock products in the real-time PPP input stage.The effectiveness of real-time orbit and clock products is analyzed,and 7-order Lagrange interpolation and the second-order polynomial clock prediction with periodic term are given for the problems of real-time orbit and clock products interruption.IGU rapid products are used to check the realtime orbit.Analyzing the different delay accuracy of clock offsets to solve the problem of the delayed use of the product;finally,use the real-time signal-in-space range error to evaluate real-time clock and orbit products to achieve comprehensive quality control.(4)The quality control method of the real-time PPP processing stage is proposed,and the quality control is realized according to the function model,random model and parameter design of this stage.A variety of function models are used to compare each other to evaluate the quality control effect;a random model that takes into account the accuracy of the signal-in-space range error is proposed,and the influence of the dynamic model with the actual signal noise and the quality of the products on the quality control of the PPP is analyzed.The optimization effect of the adaptive pseudorange-tonoise ratio model on real-time PPP is verified;in parameter estimation,Kalman filtering constrained by historical information is used to solve the problem of discontinuity in the positioning sequence caused by the interruption of observation data.(5)The quality control method of real-time PPP output stage is deeply studied.The relevant indicators of external inspection quality control and internal inspection quality control are clarified: the external inspection quality adopts two indicators such as external compliance quality control and GNSS cross-inspection.The internal inspection quality control passes internally attached quality control and based on the quality control of the protection level and other indicators ensure the reliability of the output positioning results.(6)Relying on Beidou "One Belt One Road" high-precision location and time public service platform,from the perspective of practical applications,we designed and completed a GNSS real-time precision single-point positioning cloud computing system with a complete quality control system,which can receive and process multiple types at the same time through the cloud computing system.For real-time precise products,the joint method is used to ensure the stability of real-time products,and longterm monitoring,evaluation and repair of real-time products are carried out.Solve multiple modes in parallel,check the results,and provide users with real-time precise services.In this paper,a complete GNSS real-time precision single-point positioning quality control system is designed.Based on the observation data of GNSS/BDS3,the feasibility of the real-time PPP quality control algorithm is verified.GNSS real-time PPP cloud computing system with a complete quality control system is designed and completed.The cloud computing system is applied to the Beidou "Belt and Road" highprecision location and time public service platform,which provides a certain reference value for the development and application of real-time PPP in the future,and promotes the project of real-time PPP application.