## 3 Results  
Displacements were first estimated only from baseline vectors and then from the coordinates obtained after geodetic adjustment of the network. The differences from the true values of the estimated 1D, 2D, and 3D displacements on the basis of only baseline vectors are shown in Figure 5. Table 4 presents the summary statistics for the obtained differences, such as MAE, the minimum, and the maximum values of differences, for all low-cost GNSS antennas used. Figure 4: Geodetic and low-cost GNSS devices in the four-point metal arm. Figure 5: Differences between estimated and true movements from baseline vectors only: (**a**) 1D differences, (**b**) 2D differences, and (**c**) 3D differences. The geodetic adjustment was carried out for each of the selected antennas separately, and the a posteriori standard deviation was estimated for sessions in which vertical (Table 5) and horizontal movements (Table 6) were imposed. Coordinates obtained from the geodetic adjustment were used to calculate displacements, and the presented statistical tests were applied to identify the sizes of detected movements for the selected antennas. Vertical movements were imposed in steps of 3 mm, while horizontal movements were imposed in steps of 2 mm and were also estimated in a 3D coordinate system. The results from the detection of 1D (vertical), 2D (horizontal), and 3D (spatial) displacements are shown in Tables 7-9, respectively. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Antenna**} & \multicolumn{2}{c}{**A Posteriori Standard Deviation (mm)**} \\ \cline{2-4}  & **Survey Calibrated** & **Survey** & **Tallysman** \\ \hline Session 1 & 1.1 & 1.7 & 1.7 \\ Session 2 & 1.1 & 1.6 & 1.6 \\ Session 3 & 1.3 & 1.6 & 1.6 \\ Session 4 & 1.3 & 1.9 & 1.2 \\ Session 5 & 1.0 & 1.5 & 1.8 \\ Session 6 & 1.4 & 2.0 & 1.5 \\ Session 7 & 1.2 & 1.2 & 1.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: A posteriori standard deviation: horizontal displacements. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Antenna**} & \multicolumn{2}{c}{**Survey Calibrated**} & \multicolumn{2}{c}{**Survey**} & \multicolumn{2}{c}{**Tallysman**} \\ \hline
**Dimension** & **1D** & **2D** & **3D** & **1D** & **2D** & **3D** & **1D** & **2D** & **3D** \\ \hline MAE (mm) & 1.9 & 1.2 & 1.3 & 2.3 & 1.0 & 1.6 & 3.3 & 1.7 & 2.5 \\ Max (mm) & 5.4 & 3.8 & 3.8 & 6.6 & 3.7 & 6.2 & 11.6 & 4.4 & 7.6 \\ Min (mm) & 0.1 & 0.0 & 0.1 & 0.2 & 0.0 & 0.0 & 0.4 & 0.0 & 0.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Statistics for 1D, 2D, and 3D displacements estimated from baseline vectors only. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Antenna**} & \multicolumn{2}{c}{**A Posteriori Standard Deviation (mm)**} \\ \cline{2-4}  & **Survey Calibrated** & **Survey** & **Tallysman** \\ \hline Session 1 & 0.9 & 1.8 & 2.2 \\ Session 2 & 0.9 & 2.1 & 1.9 \\ Session 3 & 0.8 & 1.6 & 2.0 \\ Session 4 & 1.4 & 1.5 & 2.0 \\ Session 5 & 1.3 & 2.0 & 1.8 \\ Session 6 & 1.4 & 1.3 & 2.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: A posteriori standard deviation: vertical displacements. For the estimated movements, the MAE was obtained to present the accuracy of 1D, 2D, and 3D displacements for each of the used antennas. These results are presented in Table 10 and show that the Survey Calibrated antenna outperforms the others. The differences in the displacements from the true values are also shown graphically in Figure 6.  
Low-cost devices were evaluated in PPP mode. The residuals of the obtained coordinates are presented in Figure 7, while the related statistics are reported in Table 11. In a dynamic test, movements of known size were imposed, and statistical tests were used to analyze the range of detected movements in PPP (Table 12). The MAE values of differences from true values are presented in Table 13 and are also graphically shown in Figure 8.