## 3 Results
### Accuracy  
The positioning accuracy was evaluated by comparing the coordinates obtained in this study with the daily reference coordinates provided in the IGS20 SINEX files. To mitigate the influence of the initial convergence period, the first 10 min of data were excluded from the analysis. Mean errors and standard deviations are summarized in Tables 6 and 7. The results obtained for the BRDM, HAS, CNES, and CODE products show significant differences in positioning accuracy, particularly depending on the GNSS signals used. For the BRDM solution, the results indicate a relatively low positioning accuracy, particularly for GPS signals. The mean errors in the N, E, and U components were \(-\)1.92 cm, 1.43 cm, and \(-\)6.14 cm, respectively, resulting in 2D and 3D accuracies of 64.83 cm and 93.18 cm. Despite relatively small mean errors, the significant standard deviations (\(\pm\)11.38 cm in N, \(\pm\)24.98 cm in E, and \(\pm\)31.78 cm in U) indicate considerable variability. For Galileo signals, although the mean errors in N, E, and U slightly increased, the 2D and 3D accuracies improved significantly, reaching 50.33 cm and 71.34 cm, respectively, which was notably better than for GPS. The use of combined GPS and Galileo (GE) signals slightly improvedthe results, with mean errors of 0.99 cm (N), \(-\)1.50 cm (E), and \(-\)0.87 cm (U), resulting in 2D and 3D accuracies of 49.57 cm and 69.40 cm, with the standard deviations remained high (\(\pm\)15.66 cm in N, \(\pm\)26.63 cm in E, \(\pm\)24.07 cm in U). For the HAS solution, the results show an intense variability for GPS. The mean errors for GPS were 0.40 cm in N, \(-\)7.87 cm in E, and \(-\)2.52 cm in U, corresponding to 2D and 3D accuracies of 86.15 cm and 128.50 cm, which are even worse than those for BRDM. GPS results were characterized by particularly large standard deviations (\(\pm\)21.81 cm in N, \(\pm\)41.82 cm in E, and \(\pm\)46.98 cm in U). A substantial improvement was observed with Galileo signals, where the mean errors decreased to 0.15 cm (N), 0.06 cm (E), and 1.47 cm (U), achieving 2D and 3D accuracies of 18.91 cm and 28.81 cm. For the GE combination, the mean errors were \(-\)0.23 cm in N, 0.09 cm in E, and 0.42 cm in U, with accuracies of 19.93 cm (2D) and 29.50 cm (3D). These results meet the requirements of the HAS service, except for GPS-only. This variability is consistent with the significantly lower availability of HAS corrections for GPS satellites, averaging around 67%, compared to over 95% for Galileo (Section 3.1). The HAS service primarily focuses on Galileo, and several GPS satellites have an availability below 50%, which negatively impacts the GPS positioning accuracy. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Solution** & **GNSS** & **N** & **E** & **U** & **2D** & **3D** \\ \hline \multirow{3}{*}{BRDM} & G & \(-\)1.9 & 1.4 & \(-\)6.1 & 64.8 & 93.2 \\  & E & \(-\)3.4 & 3.56 & \(-\)0.7 & 50.3 & 71.3 \\  & GE & 1.0 & \(-\)1.5 & \(-\)0.9 & 49.6 & 69.4 \\ \hline \multirow{3}{*}{HAS} & G & 0.4 & \(-\)7.9 & \(-\)2.5 & 86.2 & 128.5 \\  & E & 0.2 & 0.1 & 1.5 & 18.9 & 28.8 \\  & GE & \(-\)0.2 & 0.1 & 0.4 & 19.9 & 29.5 \\ \hline \multirow{3}{*}{CNES} & G & \(-\)0.5 & \(-\)1.2 & 0.0 & 5.7 & 8.0 \\  & E & \(-\)1.0 & \(-\)1.4 & \(-\)0.2 & 7.2 & 11.2 \\ \cline{1-1}  & GE & \(-\)0.6 & \(-\)1.0 & 0.0 & 4.0 & 5.7 \\ \hline \multirow{3}{*}{CODE} & G & 0.3 & \(-\)0.7 & \(-\)0.2 & 3.8 & 5.4 \\ \cline{1-1}  & E & 0.1 & 0.0 & \(-\)0.4 & 3.2 & 4.9 \\ \cline{1-1}  & GE & 0.2 & \(-\)0.2 & \(-\)0.2 & 2.2 & 3.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Mean coordinate difference to reference coordinates of all stations for all stations for all analyzed solutions. Values in cm.