## 3 Results
### Static Accuracy  
Figure 8 illustrates the relative cumulative GNSS accuracy distribution of different smartphones under a forest canopy measured at different known survey points. The multi-frequency smartphones are shown in the various shades of blue, the single-frequency smartphones in the various shades of red, the GNSS reference in olive, and the mean values in green. It becomes clear that there are significant differences between the smartphones. However, the differences between GNSS receivers vary, so it is difficult to identify the most appropriate mathematical indicator. At this point, the DRMS error will be used for comparability. Table 4 represents the characteristic values of the absolute two-dimensional position deviation of the different smartphones and GNSS receivers used in the empirical experiments. Under a forest canopy, reception conditions differ significantly in contrast to open areas. Nevertheless, the high-quality corrected Geo 7X (DRMS: 3.26 m) is the most accurate, followed by the Xiaomi Mi 10 light (DRMS: 4.56 m). The others rank from highest to lowest in the following order: Huawei P20 (DRMS: 6.92 m), Samsung A7 (DRMS: 6,94 m), Xiaomi Mi 8 (DRMS: 7.20 m), Huawei P40 (DRMS: 7.22 m), Xcover 4 sA (DRMS: 7.73 m), Xcover 4 sA (DRMS: 7.98 m), Samsung S5 (DRMS: 8.05 m), Xiaomi Mi 8 Pro (DRMS: 8.55 m), and Xcover 4 (DRMS: 14.59 m). The outdoor smartphone Xcover 4 is far behind with highly inaccurate values. Based on the measurements of the study, the multi-frequency smartphone receivers (DRMS: 6.99 m) achieve a significantly higher position accuracy under overshadowing than the single-frequency smartphones (DRMS: 9.13 m). It is worth noting that the date of manufacture may also have an influence. A newer release date and thus potentially improved hardware is not a direct prerequisite for improved reception in a forest. Figure 9a illustrates the correlation between the release date and the absolute position error (CEP). The \begin{table}
\begin{tabular}{l l c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Receivers**} & \multirow{2}{*}{**MF**} & \(\bar{x}\) & **SD** & **CEP\({}_{25}\)** & **CEP** & **CEP\({}_{75}\)** & **CEP\({}_{95}\)** & **CEP\({}_{99.7}\)** & **DRMS** & **2 DRMS** & \multirow{2}{*}{**n**} \\  & & **(m)** & **(m)** & **(m)** & **(m)** & **(m)** & **(m)** & **(m)** & **(m)** & **(m)** & **(m)** \\ \hline Geo 7X & Yes & 2.49 & 2.11 & 0.57 & 1.42 & 4.76 & 5.46 & 6.97 & 3.26 & 6.52 & 12,096 \\ P20 & No & 5.22 & 4.54 & 2.82 & 4.72 & 6.67 & 10.58 & 37.64 & 6.92 & 13.83 & 12,270 \\ P40 & Yes & 6.28 & 3.58 & 4.03 & 5.03 & 7.97 & 13.38 & 16.00 & 7.22 & 14.45 & 12,645 \\ MI 8 & Yes & 5.85 & 4.19 & 3.11 & 4.08 & 7.52 & 14.27 & 22.53 & 7.20 & 14.39 & 9492 \\ MI 8 Pro & Yes & 6.75 & 5.26 & 3.34 & 5.77 & 8.51 & 16.34 & 30.46 & 8.55 & 17.10 & 11,780 \\ Mi10 light & Yes & 3.73 & 2.62 & 1.79 & 3.28 & 5.39 & 7.89 & 16.10 & 4.56 & 9.13 & 12,627 \\ Xcover 4 & No & 10.44 & 10.19 & 4.50 & 8.05 & 11.97 & 41.99 & 47.25 & 14.59 & 29.17 & 12,333 \\ Xcover 4s\_a & No & 6.90 & 3.48 & 4.06 & 6.02 & 9.49 & 13.25 & 13.25 & 7.73 & 15.46 & 12,224 \\ Xcover 4s\_b & No & 7.20 & 3.44 & 4.34 & 7.22 & 9.22 & 12.27 & 19.72 & 7.98 & 15.96 & 12,254 \\ A7 & No & 5.86 & 3.70 & 3.40 & 5.17 & 7.06 & 15.80 & 17.74 & 6.94 & 13.87 & 11,691 \\ S5 & No & 6.73 & 4.41 & 3.26 & 6.20 & 8.14 & 16.72 & 22.55 & 8.05 & 16.09 & 11,926 \\ \hline MultiFi No & No & 7.07 & 5.77 & 3.75 & 6.02 & 8.79 & 13.64 & 41.99 & 9.13 & 18.25 & 72,698 \\ MultiFi Yes & Yes & 5.62 & 4.16 & 2.79 & 4.73 & 7.32 & 13.38 & 24.04 & 6.99 & 13.98 & 46,544 \\ All & & 6.14 & 5.17 & 3.08 & 5.03 & 8.03 & 13.38 & 41.99 & 8.03 & 16.05 & 131,338 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Characteristic values of the absolute two-dimensional position deviation of the different smartphones and GNSS receivers used in the empirical experiments.