Research on real-time precise point positioning with iGMAS ultra-fast ephemeris

The China-led International GNSS Monitoring & Assessment System (iGMAS) differs from the IGS system (international GNSS service, IGS) in product accuracy. Real-time precise point positioning (PPP) applications arc mostly based on IGS real-time and near real-time products. To improve this situation, we aimed at iGMAS product characteristics and the demand for ultra-fast products with real-time PPP, evaluated the accuracy and stability of iGMAS ultra-fast ephemeris, designed an iGMAS product real-time/post-event download application, and carried out real-time precise point positioning research based on iGMAS ultra-fast ephemeris through combining with NovAtel OEM617 dual-frequency receiver. The experimental results show that the positioning error can converge to the decimeter level after 23 minutes, which is an order of magnitude higher than the original positioning accuracy of the receiver and has good stability. The root mean square error of the positioning error in the E/N/U direction is 7.2 cm, 6.1 cm, 15.2 cm, similar to IGS ultra-fast ephemeris in real-time PPP experiment. This study implements a complete solution for iGMAS data acquisition, evaluation, and real-time PPP applications, verifies performance of iGMAS ultrafast products and provides reference for the application of iGMAS products.