## 3 Results
### Consistency of Precise Products from Different Analysis Centers
#### 3.3.3 Galileo  
The epoch-wise orbit and clock differences between GFZ and WHU precise products for Galileo on DOY 122 of 2020 are provided in Figure 5. Similar to GPS, the epoch-wise orbit differences of Galileo are usually less than 5 cm, but the clock differences are smaller than 0.3 ns for most of the time, which is better than that of GPS and GLONASS. The corresponding statistical results of Galileo are shown in Table 4. Similar to GPS and GLONASS satellites, the radial orbit difference has the smallest RMS values among the three orbital directions, while the along-track and cross-track orbit differences seem to be at a similar level for the inconsistency results only involving post-processed products, and the along-track orbit difference achieves the largest RMSs for the corresponding results between the CNES real-time products and three post-processed products. Regarding Galileo satellites, the consistency of precise satellite products between ESA and GFZ is at the highest level, and the statistics are 1.9, 2.4 and 2.5 cm, 0.06 ns and 1.7 cm in terms of radial, along-track and cross-track orbit difference, clock difference and SISRE difference, respectively. The consistency between WHU and ESA, and WHU and GFZ is also at a satisfied level, with a scattering of 2.3, 3.1 and 3.7 cm, 0.06 ns and 1.9 cm, and 2.2, 3.9 and 4.6 cm, 0.08 ns and 2.3 cm for the corresponding five different statistical terms for the two cases, respectively. As for the consistency performance between the real-time and post-processed precise satellite products, the orbital difference is slightly increased by 3.4 cm at most compared with the corresponding inconsistency results among the post-processed products, but the clock difference is enlarged by a factor of about three times, resulting in the larger SISRE difference with a value of 5.3-5.5 cm. Compared with GPS satellites, the SISRE difference of Galileo satellites is increased by approximately 0.5 cm for the inconsistency results only involving post-processed products except for those between GFZ and WHU, and is enlarged by about two times for the inconsistency between the real-time and post-processed precise satellite products.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Items**} & \multirow{2}{*}{**ACs**} & \multicolumn{3}{c}{**ACs**} \\ \cline{3-5}  & & **GFZ** & **WHU** & **CNES** \\ \hline \multirow{3}{*}{Radial (cm)} & ESA & 2.9 & 2.6 & 2.3 \\  & GFZ & – & 2.9 & 3.5 \\  & WHU & – & – & 3.3 \\ \hline \multirow{3}{*}{Along-Track (cm)} & ESA & 3.4 & 4.1 & 8.9 \\  & GFZ & – & 4.3 & 9.4 \\  & WHU & – & – & 9.5 \\ \hline \multirow{3}{*}{Cross-Track (cm)} & ESA & 3.6 & 4.0 & 5.7 \\  & GFZ & – & 4.2 & 6.6 \\  & WHU & – & – & 6.5 \\ \hline \multirow{3}{*}{Clock (ns)} & ESA & 0.10 & 0.10 & 0.18 \\  & GFZ & – & 0.18 & 0.20 \\  & WHU & – & – & 0.20 \\ \hline \multirow{3}{*}{SISRE (cm)} & ESA & 2.8 & 2.7 & 5.2 \\  & GFZ & – & 4.9 & 5.7 \\ \cline{1-1}  & WHU & – & – & 5.6 \\ \hline \hline \end{tabular}
\end{table}
Table 3: RMSs of epoch-wise differences of precise satellite orbit and clock corrections among different ACs as well as SISRE statistics for GLONASS satellites.