Satellite Based Augmentation Systems(SBASs)improve the positioning accuracy and integrity by broadcasting to the civil aviation community the corrections and integrity parameters.A snapshot algorithm based on the mini...Satellite Based Augmentation Systems(SBASs)improve the positioning accuracy and integrity by broadcasting to the civil aviation community the corrections and integrity parameters.A snapshot algorithm based on the minimum variance estimation is investigated in this study to calculate the satellite clock and orbit corrections.A chi-square test is performed on the remaining errors in the corrected ephemeris to guarantee the integrity.User Differential Range Error(UDRE)and scaling matrix contained in Message Type 28 are derived using the covariance information based on the assumption that one of the reference stations failed.A software package is developed and applied in the real data collected at 26 stations.International GNSS(Global Navigation Satellite System)Service(IGS)precise clock and orbit products are taken as the references to assess the accuracy of corrections.For both Global Positioning System(GPS)and BeiDou Navigation Satellite System(BDS),the range accuracy of 0.10 m can be achieved with the employment of the derived corrections.No obvious performance difference between GPS and BDS is found.UDREs for all visible satellites are generated with the maximum index of 12 and minimum index of 3.The geometric range differences calculated with IGS precise products and broadcast ephemeris are employed to assess the integrity of UDRE.It is found that the UDRE is able to bound the residuals with 99.9%confidence which meet the requirement of aviation users.With ionospheric delay corrected by Global Ionosphere Map(GIM),the positioning accuracy of 0.98 m with GPS corrections and 0.80 m with multi-constellation augmentation can be achieved which indicates a significant improvement of GPS standalone results.展开更多
The wide area precise positioning system(WAPPS)is a high-precision positioning system based on a global navigation satellite system.Using a GEO satellite or a communication network,it provides users,in its service are...The wide area precise positioning system(WAPPS)is a high-precision positioning system based on a global navigation satellite system.Using a GEO satellite or a communication network,it provides users,in its service area,with real-time satellite orbit,clock,and other corrections.Users can achieve centimeter-level static positioning or decimeter-level kinematic positioning by precise point positioning.With the demands for applications of both high-precision and safety of life in real time,WAPPS is facing urgent needs to improve its service integrity.This study presents a real-time integrity monitoring approach for WAPPS.Using dual-frequency ionosphere-free corrections of GPS and BDS,along with monitor station data,related error models are established and the integrity monitoring is achieved,based on the analysis of satellite corrected residuals.In addition,satellite faults are simulated for performance verification.The results show that the algorithm can monitor both step and drift faults effectively and alert users in time.展开更多
基金the Equipment Pre-research Foundation of China(No.61405180103)the National Natural Science Foundation of China(No.41974041).
文摘Satellite Based Augmentation Systems(SBASs)improve the positioning accuracy and integrity by broadcasting to the civil aviation community the corrections and integrity parameters.A snapshot algorithm based on the minimum variance estimation is investigated in this study to calculate the satellite clock and orbit corrections.A chi-square test is performed on the remaining errors in the corrected ephemeris to guarantee the integrity.User Differential Range Error(UDRE)and scaling matrix contained in Message Type 28 are derived using the covariance information based on the assumption that one of the reference stations failed.A software package is developed and applied in the real data collected at 26 stations.International GNSS(Global Navigation Satellite System)Service(IGS)precise clock and orbit products are taken as the references to assess the accuracy of corrections.For both Global Positioning System(GPS)and BeiDou Navigation Satellite System(BDS),the range accuracy of 0.10 m can be achieved with the employment of the derived corrections.No obvious performance difference between GPS and BDS is found.UDREs for all visible satellites are generated with the maximum index of 12 and minimum index of 3.The geometric range differences calculated with IGS precise products and broadcast ephemeris are employed to assess the integrity of UDRE.It is found that the UDRE is able to bound the residuals with 99.9%confidence which meet the requirement of aviation users.With ionospheric delay corrected by Global Ionosphere Map(GIM),the positioning accuracy of 0.98 m with GPS corrections and 0.80 m with multi-constellation augmentation can be achieved which indicates a significant improvement of GPS standalone results.
文摘The wide area precise positioning system(WAPPS)is a high-precision positioning system based on a global navigation satellite system.Using a GEO satellite or a communication network,it provides users,in its service area,with real-time satellite orbit,clock,and other corrections.Users can achieve centimeter-level static positioning or decimeter-level kinematic positioning by precise point positioning.With the demands for applications of both high-precision and safety of life in real time,WAPPS is facing urgent needs to improve its service integrity.This study presents a real-time integrity monitoring approach for WAPPS.Using dual-frequency ionosphere-free corrections of GPS and BDS,along with monitor station data,related error models are established and the integrity monitoring is achieved,based on the analysis of satellite corrected residuals.In addition,satellite faults are simulated for performance verification.The results show that the algorithm can monitor both step and drift faults effectively and alert users in time.
