## 2 Materials  
Assessment of Availability and Continuity of Positioning Based on the Constellation of Galileo Satellites  
The constellation of the Galileo satellites is not yet complete, and FOC is expected in 2020. For this reason, RTK test measurements were therefore only possible to be made in specific time windows within 24 h, when the number of observed satellites was at least 5 or more. In the site, Krakow-Poland (\(\phi\) = 50.0207, \(\lambda\) = 20.0221), during time span (362-365 DOY 2017 and 001-002 DOY 2018) it was possible to observe simultaneously from one to seven satellites on the elevation above 10\({}^{\circ}\) (Figure 1). Current (December 2017) the constellation of Galileo satellites, consists of 18 satellites, including 14 fully operational ones. Four satellites of the Galileo constellation are indicated as unusable \"Unh-Unhealthy\" for various reasons. Two satellites: E14, Galileo 5 (Galileo-FOC FM1, GSAT 0201, Doresa) and E18, Galileo 6 (Galileo-FOC2, GSAT 0202, Milena) launched in August 2014, due to the failure of the Russian Soyuz-ST-B Fregat-MT carrier rocket, were placed on an elliptical orbit with too high eccentricity. Therefore, they cannot be used for navigation purposes nor positioning. Moreover, the satellite E20, Galileo-IOV FM4 (GSAT0104, Sif), broadcast only 1 frequency (E1-1575.42 MHz) due to power failure which occured on 27 May 2016. It also does not send a navigational message, therefore it can not be used in precise real-time positioning (GPS World-August 2017). The satellite E22, Galileo 8 (Galileo-FOC FM4, GSAT 0204, Anastasia), from 08 December 2017 is not available. It was removed until cancellation from the active constellation, due to problems with the on-board clock. The orbits of Galileo operational satellites are located at an altitude of approximately 23.222 thousand km above the equator, which means that, on average, Galileo satellites have higher orbits by more than 3000 km relative to GPS satellites. The angle of inclination of the planes of Galileo satellites relative to the equator plane is greater by approximately 1\({}^{\circ}\) compared to the satellites of the GPS constellation. The eccentricities of the orbits of the Galileo satellites are in the range of E07 = 0.000080 to E24 = 0.000358. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Local Time: 2017-12-28 00:00:00–2017-12-29 00:00:00 (UTC + 2) Cutoff 10\({}^{\circ}\)** & \\ \hline
**Initial Time** & **End Time** & **Number of Satellites** & **Visible Satellites** & **Period of Time** \\ \hline
00:00:00 & 02:40:00 & 2–4 & E \(<\) 5 & 02:40:00 \\
02:40:00 & 03:40:00 & 5 & E02, E11, E12, E19, E24 & 01:00:00 \\
03:40:00 & 04:10:00 & 6 & E02, E04, E11, E12, E19, E24 & 00:30:00 \\
04:10:00 & 05:00:00 & 5 & E02, E04, E11, E12, E19 & 00:50:00 \\
05:00:00 & 05:50:00 & 7 & E02, E04, E09, E11, E12, E19, E30 & 00:50:00 \\
05:50:00 & 06:10:00 & 6 & E02, E04, E09, E11, E19, E30 & 00:20:00 \\
06:10:00 & 06:30:00 & 5 & E02, E04, E09, E11, E30 & 00:20:00 \\
06:30:00 & 06:50:00 & 4 & E \(<\) 5 & 00:20:00 \\
06:50:00 & 07:00:00 & 5 & E04, E05, E09, E11, E30 & 00:10:00 \\
07:00:00 & 13:10:00 & 2–4 & E \(<\) 5 & 06:10:00 \\
13:10:00 & 13:20:00 & 5 & E02, E03, E05, E08, E24 & 00:10:00 \\
13:20:00 & 14:10:00 & 6 & E02, E03, E05, E08, E24, E26 & 00:50:00 \\
14:10:00 & 14:20:00 & 5 & E02, E03, E08, E24, E26 & 00:10:00 \\
14:20:00 & 14:40:00 & 6 & E02, E03, E07 / E08, E24, E26 & 00:20:00 \\
14:40:00 & 15:00:00 & 5 & E02, E03, E07 / E08, E26 & 00:20:00 \\
15:00:00 & 16:50:00 & 5 & E02, E03, E07 / E08, E30 & 01:50:00 \\
16:50:00 & 00:00:00 & 1–4 & E \(<\) 5 & 07:10:00 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Galileo satellites availability for the Day of Year: 363, 2017.