## 2 Materials and Methods
As part of the study, two receivers were used: Simrad MXB5 (DGPS) and Trimble GA530 (EGNOS), which simultaneously recorded their position coordinates with a frequency of 1 Hz. The obtained values were compared with the precise GNSS receivers (Trimble R10), using corrections from an active geodetic network with an accuracy of 2-3 cm (\(p\) = 0.95). During a 4-hour measurement session, the accuracy statistics of these systems were determined based on approximately 11,500 positions (Table 1) [37]. * Stationary measurements of the multi-GNSS systems using the example of Samsung Galaxy smartphones, carried out on the rooftop of the National Sailing Centre in Gdansk on 17 July 2017. As part of the study, the following smartphones were used: S2, S3 Mini, S4, S5, S6, S7, and Y, whose coordinates (antennas) were determined using geodetic methods, and with their use, a round-the-clock measurement campaign was carried out. It consisted of parallel registration of position coordinates by all telephones. During a 24-hour measurement session, between 71,438 and 86,371 positions were registered depending on the smartphone model (Table 2) [38]. * Dynamic measurements of the multi-GNSS systems using the example of Samsung Galaxy smartphones, carried out during vessel manoeuvring on the Gdansk Bay on 20 June 2017. For the comparative analysis, five Samsung Galaxy S series smartphones were used, namely: 3 Mini, 4, 5, 6, 7, and one Galaxy Y. As part of the parallel tracking studies, the telephone positions were compared to those of precise GNSS receivers (Trimble R10) using corrections from an active geodetic network with an accuracy of 2-3 cm (\(p\) = 0.95). As a result of the 4-hour measurement, the accuracy statistics for each of the phone models were defined based on approximately 10,000 positions (Table 3) [36]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Statistics of Position Error** & **DGPS 2014 (S)** & **EGNOS 2014 (S)** & **DGPS 2017 (D)** & **EGNOS 2017 (D)** \\ \hline Number of measurements & 951,698 & 927,553 & 11,751 & 11,698 \\
2 DRMS (2D) & 0.96 m & 3.27 m & 1.48 m & 2.39 m \\ R95 (2D) & 0.83 m & 2.31 m & 1.42 m & 1.79 m \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Statistics for the DGPS and EGNOS systems’ predicted position errors during the course of the stationary (S) and dynamic (D) measurement campaigns [35]. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Statistics of Position Error** & \multicolumn{6}{c}{**Samsung Galaxy Series**} \\ \cline{2-7}  & **Y** & **S3 Mini** & **S4** & **S5** & **S6** & **S7** \\ \hline Number of measurements & 73,699 & 71,438 & 86,290 & 86,346 & 86,371 & 86,355 \\
2 DRMS (2D) & 5.61 m & 6.79 m & 2.04 m & 2.06 m & 13.69 m & 8.93 m \\ R95 (2D) & 4.93 m & 3.76 m & 1.65 m & 1.76 m & 12.64 m & 8.39 m \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Statistics for the Samsung Galaxy phones’ predicted position errors over the course of a 24-hour stationary measurement campaign [38]. The data originating from multi-GNSS receivers were handled in a similar manner. For the analyses, measurement data from both the stationary and dynamic campaigns described in detail in References [36; 38] were used. These are measurement data originating from five Samsung Galaxy S series smartphones, designated successively with the following numbers: 3 Mini, 4, 5, 6, 7, and Galaxy Y. The final results of classical accuracy analyses are presented in Table 2 (stationary measurements) and Table 3 (dynamic measurements). The results of tests on the DGPS and EGNOS systems, as well as the multi-GNSS receivers presented in the tables, refer to a confidence level of 0.95 where position errors corresponding to this value were determined. They were obtained using two commonly applied methods, i.e., through the determination of a standard deviation with an assumed normal distribution of errors and through grading the errors from the lowest to the highest value in order to determine the R95 value.