## 3 Results
### Orbit Comparisons with GFZ Final Multi-GNSS Orbits  
The satellite positions of two individual orbit products are compared in radial, alongside, cross-tracking (RAC) components and 1-D. The real-time POD is completed in one hour, and thus, the orbit within the second hour of each prediction in one day is extracted and merged to a complete 24 h orbit; then, the merged 24 h orbit is compared with GFZ's final daily multi-GNSS orbit. Finally, the mean RMS of each component for each satellite in all constellations from 1 June 2021 to 31 May 2022 is presented, and the results are shown in Figures 4-8 and listed in Tables 4-8. Meanwhile, time series of the 1-D for each constellation are illustrated in Figures 9-13. Statistics show that the mean 1-D RMS value over the RAC components is approximately 3.7 cm, 10.2 cm, 5.8 cm, 5.7 cm, 4.1 cm and 25.1 cm for GPS, BDS IGSOs, BDS MEOs, GLONASS, Galileo and QZSS NONE GEOs, respectively. As for the radial component, the mean RMS is approximately 1.7 cm, 5.8 cm, 3.4 cm 2.5 cm, 1.8 cm and 10.9 cm for GPS, BDS IGSOs, BDS MEOs, GLONASS, Galileo and QZSS NONE GEOs, respectively. Figure 4: Mean RMS in the RAC components and 1-D of GPS satellites in comparison with GFZ final orbit. Figure 5: Mean RMS in the RAC components and 1-D of BDS NONE GEO satellites in comparison with GFZ final orbit. Figure 6: Mean RMS in the RAC components and 1-D of GLONASS satellites in comparison with GFZ final orbit. Figure 7: Mean RMS in the RAC components and 1-D of Galileo satellites in comparison with GFZ final orbit. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**PRN of GPS** & **Radial (cm)** & **Along (cm)** & **Cross (cm)** & **1-D (cm)** \\ \hline G01 & 1.5 & 5.0 & 2.9 & 3.5 \\ G02 & 1.7 & 5.7 & 3.3 & 3.9 \\ G03 & 1.5 & 5.1 & 2.9 & 3.5 \\ G04 & 1.6 & 5.2 & 3.1 & 3.6 \\ G05 & 1.6 & 5.4 & 3.1 & 3.7 \\ G06 & 1.6 & 5.1 & 3.0 & 3.5 \\ G07 & 1.8 & 5.7 & 3.4 & 4.0 \\ G08 & 1.6 & 5.0 & 3.0 & 3.5 \\ G09 & 1.5 & 4.8 & 2.8 & 3.3 \\ G10 & 1.6 & 4.8 & 2.9 & 3.4 \\ G11 & 2.0 & 6.2 & 3.7 & 4.3 \\ G12 & 1.6 & 5.3 & 3.2 & 3.7 \\ G13 & 1.7 & 5.4 & 3.3 & 3.8 \\ G14 & 1.7 & 5.4 & 3.3 & 3.8 \\ G15 & 1.7 & 5.4 & 3.2 & 3.8 \\ G16 & 1.7 & 5.5 & 3.3 & 3.8 \\ G17 & 1.7 & 5.7 & 3.3 & 3.9 \\ G18 & 1.8 & 5.8 & 3.4 & 4.0 \\ G19 & 1.7 & 5.7 & 3.3 & 3.9 \\ G20 & 1.6 & 5.4 & 3.1 & 3.7 \\ G21 & 1.7 & 5.6 & 3.2 & 3.9 \\ G22 & 1.7 & 5.5 & 3.2 & 3.8 \\ G23 & 1.8 & 5.7 & 3.4 & 3.9 \\ G24 & 1.5 & 5.0 & 2.9 & 3.4 \\ G25 & 1.5 & 4.9 & 2.8 & 3.4 \\ G26 & 1.6 & 5.0 & 3.0 & 3.5 \\ G27 & 1.5 & 4.8 & 2.9 & 3.4 \\ G28 & 1.7 & 5.4 & 3.2 & 3.8 \\ G29 & 1.7 & 5.6 & 3.3 & 3.9 \\ G30 & 1.6 & 5.0 & 3.0 & 3.5 \\ G31 & 1.8 & 5.7 & 3.4 & 4.0 \\ G32 & 1.5 & 4.8 & 2.8 & 3.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Mean RMS value of GPS satellites in comparison with GFZ final orbit. Figure 8: Mean RMS in the RAC components and 1-D of QZSS NONE GEO satellites in comparison with GFZ final orbit. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**PRN of** & **Radial (cm)** & **Along (cm)** & **Cross (cm)** & **1-D (cm)** \\
**GLONASS** & **Radial (cm)** & **Along (cm)** & **Cross (cm)** & **1-D (cm)** \\ \hline R01 & 3.0 & 9.4 & 5.6 & 6.6 \\ R02 & 2.3 & 7.3 & 4.4 & 5.1 \\ R03 & 2.4 & 7.7 & 4.5 & 5.3 \\ R04 & 2.3 & 7.4 & 4.4 & 5.1 \\ R05 & 2.6 & 8.4 & 4.9 & 5.8 \\ R07 & 2.4 & 7.7 & 4.6 & 5.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Mean RMS value of GLONASS satellites in comparison with GFZ final orbit. \begin{table} \begin{tabular}{c c c c c} \hline \hline
**PRN of BDS** & **Radial (cm)** & **Along (cm)** & **Cross (cm)** & **1-D (cm)** \\ \hline C06 & 4.8 & 15.4 & 9.2 & 10.7 \\ C07 & 4.7 & 15.2 & 9.0 & 10.6 \\ C08 & 4.5 & 14.4 & 8.6 & 10.0 \\ C09 & 4.2 & 14.1 & 8.1 & 9.7 \\ C10 & 4.3 & 13.8 & 8.1 & 9.6 \\ C13 & 4.2 & 14.3 & 8.3 & 9.8 \\ C16 & 4.7 & 14.9 & 8.9 & 10.4 \\ \hline \hline \end{tabular} 
**BDS-2 MEOs** & & & \\ \hline C11 & 3.5 & 8.0 & 4.6 & 5.7 \\ C12 & 3.4 & _7.7_ & 4.5 & 5.5 \\ C14 & 3.5 & 8.2 & 4.8 & 5.8 \\ \hline \hline \end{tabular} \