Orbits Quality and PPP Application for Galileo
The orbit quality and PPP application of the Galileo precise products from five MGEX analysis centers (AC) are analyzed in this article, the influence of Solar Radial Pressure (SRP) model on Precise Orbit Determination (POD) is studied. The results show that: the quality of Galileo orbit from GFZ and TUM is significantly improved if the Cuboid Box-Wing (CBW) priori model is used. The SLR residual amplitudes reduced from 20 cm down to 10 cm, the STD has decreased about 50%, and the mean SLR bias is reduced from −2.0 to −6.0 cm to millimeters level; and PHMs clock-offsets daily linear fitting results also show that the periodic signature could be significantly reduced, which is consistent with the results of SLR residuals. CODE’s ECOM2 model shows slightly worse performance than CBW + ECOM1 model, but much better than classic ECOM1 model. In addition, the mean SLR bias of CODE’s and WHU’s orbits is about −2.0 to 4.0 cm, too larger than the result of other Analysis Center, so that the impact of albedo model and antenna thrust require appropriate consideration. Precise point positioning (PPP) error of Galileo-only is about 1.0 cm in horizontal, which is very close to the results of GPS-only, but larger than 3.0 cm in vertical component due to the limited number of active satellites. The convergence speed of GPS/Galileo combined solution is faster than any single system, the positioning accuracy in horizontal is improved respect to GPS-only, but a small degradation can be observed in vertical component.
KeywordsGalileo system Precise orbit determination SLR residuals Solar radiation model PPP
The IGS MGEX and ILRS are greatly acknowledged for providing the multi-GNSS and SLR tracking data. This work was supported by National Key Research Program of China “Collaborative Precision Positioning Project” (No. 2016YFB0501900).
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