High-Precision GLONASS Orbit Prediction for Real-Time Precise Point Positioning

Abstract

With the revitalization of GLONASS constellation, it becomes feasible to integrate the GLONASS into the conventional GPS-only real-time precise point positioning (PPP) processing to enhance system availability and reliability. As generation of real-time orbit corrections is a crucial part of the real-time PPP system, a high-precision GLONASS orbit prediction method is proposed and evaluated in this paper. First, the concept of a new real-time PPP system will be briefly introduced. Then, GLONASS orbit prediction method is presented with an emphasis on assessing the differences of the full 9 parameters empirical CODE orbit model (ECOM) solar radiation pressure (SRP) model and the reduced 5 parameters ECOM SRP model. Finally, the generated orbits are compared with the observed part of the GFZ ultra-rapid products. Furthermore, the orbit quality is assessed in both static and kinematic PPP experiments. It is shown that an average accuracy for 12 h orbit prediction using the full ECOM model are 0.019, 0.085, and 0.029 m in the radial, along-track and cross-track direction, respectively. The average accuracy of static PPP positioning for 5 global IGS stations are 0.019, 0.019, 0.031 m in the east, north and up direction, respectively; while the average accuracy of kinematic PPP is 0.136, 0.090, 0.256 m in the east, north and up direction, respectively. Meanwhile, utilization of the reduced 5 parameters ECOM solar radiation pressure model will not degrade the orbit prediction accuracy significantly and therefore comparable positioning performance can be achieved.