## 2 Materials and Methods
The position of the prism is read from the division, and, when converted into the appropriate unit, directly represents the horizontal distance to the point being measured. The precision of distance measurements is 0.06% or 0.03 mm per 5 cm. Figure 4: Zeiss BRT 006 basis-reuktionstachymeter. Figure 3: Experimental setup. Figure 2: UZEL test station. To assess the displacement determination accuracy of the low-cost GNSS receiver, the GNSS antenna mounted on the Zeiss BRT 006 basis-reduktionstachymeter was sequentially moved by increments of 2, 4, 6, 8, 10, 20, 30, 40, and 50 mm. Following each movement, GNSS data were collected continuously for a period of 24 h. This process was repeated over 10 days, constituting the test measurements throughout this study. The 24 h data obtained from the measurements were then divided into 3, 6, 8, and 12 h groups to analyze the impact of measurement duration on displacement determination accuracy. The TEQC software (2019 release) [36] was utilized to divide the 24 h data into 3, 6, 8, and 12 h segments. During the measurements, a data recording interval of 30 s was applied, and the measurements were conducted in an open-sky condition with a low multipath environment. The measurement schedule applied for various displacement magnitudes is given in Table 3. The time intervals of the 3, 6, 8, and 12 h data obtained by dividing the 24 h GNSS data are given in Table 4.  
The GNSS data for the time intervals given in Table 4 were processed using the GAMIT/GLOBK software (v10.7). The data were analyzed in GAMIT software at first to estimate UZEL site coordinates with loose a priori constraints. To link our station to the global network, the IGS stations, shown in Figure 5 with blue triangles, were used in the analysis. NICO, RAMO, ZECK, GRAZ, WTZR, WSRT, and YEBE IGS stations were used for processing the GNSS data at UZEL station because of the data availability and stability of these stations. In the GLOBK (Global Kalman filter) stage, the output from GAMIT, as loosely constrained coordinate estimations, was used to estimate the daily coordinates. After obtaining precise coordinates, the differences between estimated coordinate values were compared with displacement values generated using the Zeiss BRT 006 basis-reduktionstachymeter. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **3 h** & **6 h** & **8 h** & **12 h** \\ \hline  & 00:00–03:00 & & & \\  & 03:00–06:00 & & & \\  & 06:00–09:00 & 00:00–06:00 & & \\ Time interval & 09:00–12:00 & 06:00–12:00 & & 00:00–08:00 & \\  & 12:00–15:00 & 12:00–18:00 & & 08:00–16:00 & \\  & 15:00–18:00 & 18:00–24:00 & & 16:00–24:00 & \\  & 18:00–21:00 & & & \\  & 21:00–24:00 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The time intervals of the 3, 6, 8, and 12 h data. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Period (Day)** & **Displacement (mm)** & **GPS Days** & **Observation Time (Hours)** & **Record Interval (Seconds)** \\ \hline \(1\) (Initial) & 0 & 076 & 24 & 30 \\ \(2\) & 2 & 077 & 24 & 30 \\ \(3\) & 4 & 078 & 24 & 30 \\ \(4\) & 6 & 079 & 24 & 30 \\ \(5\) & 8 & 080 & 24 & 30 \\ \(6\) & 10 & 081 & 24 & 30 \\ \(7\) & 20 & 082 & 24 & 30 \\ \(8\) & 30 & 082 Deformation of a point is defined as statistically significant displacement of the point between two epochs. The horizontal position of a point is \(Pt\) (\(n_{t}\), \(e_{t}\)) at time (\(t\)) and \(P_{t+\Delta t}\) (\(n_{t+\Delta t}\), \(e_{t+\Delta t}\)) at time (\(t+\Delta t\)). Displacement is determined by calculating the difference between the estimated coordinates at time (\(t\)) and time (\(t+\Delta t\)):  
\[P_{t+\Delta t}-P_{t}= \begin{bmatrix}\Delta n\\ \Delta e\end{bmatrix} = \begin{bmatrix}n_{t+\Delta t}-n_{t}\\ e_{t+\Delta t}-e_{t}\end{bmatrix}