# Investigation on Reference Frames and Time Systems in Multi-GNSS
## 2 Quality Check of Broadcast Orbits
### RSW Components of Coordinate Differences and Clock Differences
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Satellite** & **Radial (m)** & **Along-Track (m)** & **Cross-Track (m)** & **Clock (ns)** & **Block** & **Clock \({}^{1}\)** \\ \hline R01 & \(0.10\pm 0.41\) & \(-0.42\pm 0.70\) & \(-0.19\pm 0.62\) & \(-2.4\pm 3.0\) & M & Cs \\ R02 & \(0.07\pm 0.44\) & \(-0.03\pm 1.13\) & \(-0.14\pm 0.67\) & \(-6.1\pm 5.8\) & M & Cs \\ R03 & \(0.08\pm 0.40\) & \(0.78\pm 0.87\) & \(-0.12\pm 0.97\) & \(20.1\pm 6.0\) & M & Cs \\ R04 & \(0.08\pm 0.41\) & \(-0.72\pm 1.10\) & \(-0.16\pm 0.45\) & \(22.2\pm 6.3\) & M & Cs \\ R05 & \(0.08\pm 0.39\) & \(1.22\pm 1.58\) & \(-0.18\pm 0.90\) & \(-1.5\pm 5.8\) & M & Cs \\ R06 & \(0.16\pm 0.47\) & \(0.79\pm 1.72\) & \(-0.17\pm 0.54\) & \(0.1\pm 5.9\) & M & Cs \\ R07 & \(0.14\pm 0.38\) & \(0.46\pm 1.01\) & \(-0.12\pm 0.62\) & \(14.6\pm 4.3\) & M & Cs \\ R08 & \(0.12\pm 0.41\) & \(-0.41\pm 1.15\) & \(-0.15\pm 0.97\) & \(24.3\pm 4.4\) & M & Cs \\ R09 & \(0.00\pm 0.58\) & \(0.00\pm 0.79\) & \(0.00\pm 0.36\) & \(10.3\pm 3.9\) & K & Cs \\ R10 & \(-0.29\pm 0.49\) & \(-0.21\pm 0.73\) & \(0.18\pm 1.06\) & \(-13.9\pm 7.2\) & M & Cs \\ R11 & \(0.05\pm 0.42\) & \(1.91\pm 0.89\) & \(0.18\pm 0.65\) & \(6.4\pm 5.3\) & M & Cs \\ R13 & \(0.08\pm 0.46\) & \(-0.31\pm 2.35\) & \(0.15\pm 0.73\) & \(-3.1\pm 4.7\) & M & Cs \\ R14 & \(-0.30\pm 0.46\) & \(-0.23\pm 2.94\) & \(0.14\pm 0.93\) & \(-20.2\pm 9.7\) & M & Cs \\ R15 & \(-0.30\pm 0.49\) & \(-1.13\pm 2.32\) & \(0.09\pm 0.99\) & \(0.6\pm 9.9\) & M & Cs \\ R16 & \(-0.01\pm 0.44\) & \(1.31\pm 1.12\) & \(0.09\pm 0.69\) & \(3.7\pm 5.2\) & M & Cs \\ R17 & \(0.03\pm 0.62\) & \(2.31\pm 0.88\) & \(-0.13\pm 0.74\) & \(11.8\pm 5.0\) & M & Cs \\ R18 & \(-0.01\pm 0.48\) & \(0.31\pm 0.87\) & \(-0.15\pm 0.76\) & \(-4.6\pm 4.3\) & M & Cs \\ R19 & \(0.06\pm 0.66\) & \(1.06\pm 2.00\) & \(-0.09\pm 0.78\) & \(6.9\pm 5.9\) & M & Cs \\ R20 & \(-0.35\pm 0.64\) & \(0.01\pm 2.19\) & \(-0.11\pm 0.71\) & \(5.1\pm 4.8\) & M & Cs \\ R21 & \(0.02\pm 0.53\) & \(0.35\pm 0.82\) & \(-0.08\pm 0.66\) & \(13.1\pm 4.7\) & M & Cs \\ R22 & \(0.03\pm 0.46\) & \(-1.17\pm 1.87\) & \(-0.07\pm 0.72\) & \(0.0\pm 7.5\) & M & Cs \\ R23 & \(-0.05\pm 0.52\) & \(1.78\pm 0.97\) & \(-0.08\pm 0.67\) & \(22\pm 4.7\) & M & Cs \\ R24 & \(0.18\pm 0.57\) & \(-0.96\pm 1.02\) & \(-0.09\pm 0.79\) & \(6.2\pm 3.5\) & M & Cs \\ \hline \end{tabular} \({}^{1}\)  
\end{table} 
Table 3: GLONASS mean values and standard deviations of coordinates and clock differences. For Galileo, gaps have been found in the spacing between I/NAV ephemeris blocks larger than the validity period of the ephemeris block, i.e., \(\pm\)3600 s. This prevents the computation of satellite coordinates and clock in the gaps. The availability of broadcast ephemeris is shown in Figure 7, where each block of healthy ephemeris is plotted with a circular black marker and each block of unhealthy ephemeris is plotted with a cross-shaped gray marker. In the studied days all the ephemeris blocks were set to healthy. In the periods of continuity of validity of ephemeris, it is possible to notice discontinuities in satellite coordinates (mostly in the along-track component) and clock. For Galileo, the coordinate differences show an oscillating trend with a period of about 12 h. The average values of standard deviations are 0.14, 0.29, 0.16 m and 1.3 ns for the radial, along-track, cross-track and clock component, respectively. The average values of clock differences range between 0.7 and 7.8 ns. The magnitude of discontinuities is up to 0.2, 1.0, 0.3 m and 2 ns for the radial, along-track, cross-track and clock component, respectively. E14 and E18 show scattered coordinate differences with very large (>5 m) values, so about 75% of coordinates are rejected by Bernese and not considered in the estimating of Helmert parameters. Their clock differences show an offset of about 4-8 ns, with the same standard deviation of the other satellites. Mean values and standard deviations of coordinates and clock differences for each satellite are reported