Analysis of Parameter Correlations of the ECOM Solar Radiation Pressure Model for GPS Orbit

Tae-Suk Bae,Chang-Ki Hong

doi:10.1155/2019/5190496

Abstract

The modeling of solar radiation pressure is the most important issue in precision GNSS orbit determination and is usually represented by constant and periodic terms in three orthogonal axes. Unfortunately, these parameters are generally correlated with each other due to overparameterization, and furthermore, the correlation does not remain constant throughout a long-term period. A total of 500 weeks of GPS daily solutions were estimated with the empirical CODE orbit model (ECOM) to cover various block types of satellites. The statistics of the postfit residuals were analyzed in this study, which shows the dominant annual variation of the correlations over time. There is no significant difference between eclipsing and noneclipsing satellites, and the frequency of the correlation exactly corresponds to the GPS draconitic year. Based on the residual analysis, the ECOM is the most appropriate for the Block IIR/IIR-M satellites but does not properly account for the behavior of either older Block IIA or newer IIF satellites. In addition, the daily mean residuals show a different pattern for satellite orbital planes. Therefore, the orbit model should be customized for the block types and orbital plane for better representation of multi-GNSS orbits.

Highlights

Since the early effort of Fliegel et al [1] with a ROCK model, considerable progress has been made in the modeling of the solar radiation pressure (SRP) on GPS satellites
Since a satellite can be replaced by a new one with the same PRN near the end of its design life, it is plotted by the satellite vehicle number (SVN)
We calculated 500 weeks of GPS orbit solutions to validate the SRP models based on the correlation of the parameters and the residuals

Summary

Introduction

Since the early effort of Fliegel et al [1] with a ROCK model, considerable progress has been made in the modeling of the solar radiation pressure (SRP) on GPS satellites. The approach was adapted by Beutler et al [3] in the Bernese GPS Software with slightly different axes to absorb the unmodeled forces in the acceleration of the satellites. This model, called the empirical CODE orbit model (ECOM), is composed of nine parameters in three orthogonal axes including the satellite-Sun vector and the spacecraft’s solar panel axis.

Objectives

Methods

Findings

Conclusion