Multi-GNSS Precise Point Positioning enhanced by the real navigation signals from CENTISPACETM LEO mission

The Low Earth Orbit (LEO) satellites can significantly reduce the convergence time of Precise Point Positioning (PPP), as the rapid motion of LEO satellites leads to the fast changes of the observation geometry. This helps to accelerate the separation of ambiguity as well as receiver’s positions. In this study, the real dual-frequency navigation signals of the CENTISPACETM ESAT1 satellite are used to enhance the Multi-GNSS Precise Point Positioning (PPP). The onboard GPS, Galileo and BDS-3 observations are used to derive the precise orbits of ESAT1, while the clock is determined based on the data from a ground network established by Wuhan University. With them, the impact of the ESAT1 on float PPP with single, dual, and three constellations (GPS-only, Galileo-only, BDS-3 only, GPS/Galileo, GPS/BDS-3, Galileo/BDS-3, and GPS/Galileo/BDS-3) is analyzed in terms of convergence time and positioning accuracy. The analysis reveals that the average convergence time in the east direction is reduced by 7.9, 2.4, 12.0, 2.0, 3.4, 2.6 and 1.3 min respectively. Additionally, the 3D accuracy improves around 3.2, 4.1, 5.8, 1.1, 0.3, 1.5 and 0.6 cm respectively. Furthermore, the contribution of ESAT1 observations for Mult-GNSS PPP with Ambiguity Resolution (PPP-AR) is also investigated. The average Time to First Fix (TTFF) of each solution can be reduced about 8.1, 5.2, 4.9, 1.3, 0.9, 1.1 and 0.4 min, respectively. Overall, the PPP and PPP-AR are benefited with LEO signals, in particularly for the single-system solutions, and the results demonstrate the promising contribution of LEO on high-accuracy positioning.