GPS Satellite Orbit Prediction at User End for Real-Time PPP System.

Hongzhou Yang,Yang Gao

doi:10.3390/s17091981

Abstract

This paper proposed the high-precision satellite orbit prediction process at the user end for the real-time precise point positioning (PPP) system. Firstly, the structure of a new real-time PPP system will be briefly introduced in the paper. Then, the generation of satellite initial parameters (IP) at the sever end will be discussed, which includes the satellite position, velocity, and the solar radiation pressure (SRP) parameters for each satellite. After that, the method for orbit prediction at the user end, with dynamic models including the Earth’s gravitational force, lunar gravitational force, solar gravitational force, and the SRP, are presented. For numerical integration, both the single-step Runge–Kutta and multi-step Adams–Bashforth–Moulton integrator methods are implemented. Then, the comparison between the predicted orbit and the international global navigation satellite system (GNSS) service (IGS) final products are carried out. The results show that the prediction accuracy can be maintained for several hours, and the average prediction error of the 31 satellites are 0.031, 0.032, and 0.033 m for the radial, along-track and cross-track directions over 12 h, respectively. Finally, the PPP in both static and kinematic modes are carried out to verify the accuracy of the predicted satellite orbit. The average root mean square error (RMSE) for the static PPP of the 32 globally distributed IGS stations are 0.012, 0.015, and 0.021 m for the north, east, and vertical directions, respectively; while the RMSE of the kinematic PPP with the predicted orbit are 0.031, 0.069, and 0.167 m in the north, east and vertical directions, respectively.

Highlights

precise point positioning (PPP) is the state space solution to derive centimeter-level positioning accuracy using a single receiver and IGS precise clock and orbit products [1]
This paper firstly introduces a new real-time PPP system in terms of server end, communication
This paper firstly introduces a new real-time PPP system in terms of server end, communication end, and user end; the orbit prediction is discussed, including the generation of a low update end, and user end; the orbit prediction is discussed, including the generation of a low update rate initial parameters (IP) at the sever end, and orbit predictions of satellite orbit at the user end

Summary

Introduction

PPP is the state space solution to derive centimeter-level positioning accuracy using a single receiver and IGS precise clock and orbit products [1]. A crucial aspect for real-time PPP [2] is the availability of precise real-time satellite orbit and clock products In recognition of this demand from the user community, the IGS formed a real-time working group in 2001 to develop technologies, standards and infrastructure for real-time service (RTS). Current real-time PPP system using IGS RTS and other commercial services require a continuous connectivity for PPP users to continuously receive precise orbit and clock corrections at a high update rate. The high update rate orbit and clock corrections in the new real-time PPP system are to be clock corrections in the new real-time PPP system are to be generated based on the low update rate generated based on the low update rate initial parameters by the user system, instead of receiving initial parameters by the user system, instead of receiving from the server system via high-connectivity from the server system via high-connectivity communication systems.

Generation of Satellite Orbit Initial Parameters at Server End

Generation of Satellite Orbit at User End

Comparison withsatellite the IGSorbits

The distribution of of thethe selected stations forfor static

Kinematic PPP

Conclusions