## 5 Smartphone Positioning Results  
Considering the first positioning test on 15 January, a Huawei P30 Pro was mounted in vertical position on a tripod. Static coordinate results were computed based on carrier phase observations obtained from the OPNT permanent station (4 km away) and compared to the reference position. We subdivided the observation data into sessions of shorter duration of 10, 15, 20, 30 and ending on 60 min. For all time intervals, the best results were obtained with GPS-only L1 carrier phase observations, where all the ambiguities were fixed. The computation of baseline coordinates in all cases was provided by Topcon Tools software. During the 1 h session, the number of observed GPS satellites did not drop below 6, with an average number of 8 satellites. Figures 6-10 and Tables 1-5 present results of the first initial test, after a comparison to the reference position. Figure 8: 20 min sub-session positioning results for initial test, baseline OPNT–P30 Pro (4 km). Figure 10: 60 min session positioning results for initial test, baseline OPNT–P30 Pro (4 km). Figure 9: 30 min sub-session positioning results for initial test, baseline OPNT–P30 Pro (4 km). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Minutes** & **dx (m)** & **dy (m)** & **dh (m)** \\ \hline
0–15 & 0.005 & 0.025 & \(-\)0.027 \\ \hline
15–30 & 0.055 & 0.078 & 0.413 \\ \hline
30–45 & 0.002 & 0.018 & \(-\)0.018 \\ \hline
45–60 & 0.019 & 0.002 & \(-\)0.016 \\ \hline min & 0.002 & 0.002 & \(-\)0.027 \\ \hline max & 0.055 & 0.078 & 0.413 \\ \hline SD & 0.025 & 0.033 & 0.217 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: 15 min sub-session positioning results summary, baseline OPNT–P30 Pro (4 km). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Minutes** & **dx (m)** & **dy (m)** & **dh (m)** \\ \hline
0–20 & 0.000 & 0.024 & \(-\)0.028 \\ \hline
20–40 & \(-\)0.007 & 0.019 & \(-\)0.006 \\ \hline
40–60 & 0.013 & 0.009 & \(-\)0.021 \\ \hline min & \(-\)0.007 & 0.009 & \(-\)0.0 In the second positioning test on 22 January, a Huawei P30 Pro was mounted, also in a vertical position, but on an aluminum beam. The complete surveying session lasted 60 min. As mentioned before, for signal quality comparisons, a Javad Alpha geodetic receiver was mounted in the north-end location, 0.50 m away from a mobile phone. Static coordinate results were also computed based on carrier phase observations obtained from the OPNT permanent station and compared to the reference position. Again, we subdivided the observation data into sessions of shorter duration. Based on previous experience, GPS-only L1 carrier phase observations where used to process collected data in Topcon Tools post-processing software. The same as in the previous experiment, all the ambiguities were fixed. During this session, the number of observed GPS satellites did not drop below 5, and the average number was the same as before (8 satellites). Results of this experiment are presented in the Figures 11-15 and Tables 6-10 below. Figure 14: 30 min sub-session positioning results for the second test, baseline OPNT–P30 Pro (4 km). Figure 13: 20 min sub-session positioning results for the second test, baseline OPNT–P30 Pro (4 km). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Minutes** & **dx (m)** & **dy (m)** & **dh (m)** \\ \hline
0–10 & \(-\)0.504 & \(-\)0.032 & 0.591 \\ \hline
10–20 & 0.002 & \(-\)0.022 & \(-\)0.003 \\ \hline
20–30 & 0.001 & \(-\)0.009 & \(-\)0.022 \\ \hline
30–40 & \(-\)0.369 & 0.108 & 0.074 \\ \hline
40–50 & \(-\)0.507 & 0.107 & 0.767 \\ \hline
50–60 & \(-\)0.097 & \(-\)0.209 & 0.208 \\ \hline min & \(-\)0.507 & \(-\)0.209 & \(-\)0.022 \\ \hline max & 0.002 & 0.108 & 0.767 \\ \hline SD & 0.243 & 0.116 & 0.332 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: 10 min sub-session positioning results summary, baseline OPNT–P30 Pro (4 km).