## 3 Setup and Measurement Campaign
### Jamming Experiments from DOY 263  
On DOY 263, the first session was conducted differently, with the jammer on the pole carried by a walking person (\"walking experiment\") (Figure 6a).  
Receivers were placed in the same locations for day DOY 263 (sites 1-6) as for DOY 262, as shown in Figure 4b. In the first session of DOY 263, the walking scenario of jamming was conducted to determine the positions of the jammers for each time stamp using the total station. The placement of the device types for each site is shown in Table 1, and the receivers for each site are listed in Table 6.  
The coordinates of the jammers were determined in advance using a relative static method with respect to a reference point of the Slovenian continuously operating GNSS reference network, SIGNAL. In the walking scenario, the jammer was attached to a pole directly under the 360\({}^{\circ}\) prism, the positions of which were determined using the tachymeter positioning system (TPS). Since positioning during the jamming was undertaken using a total station, this allowed the position of the jammer and, in addition, the distances between the receivers and the jammer to be accurately determined at certain times. In the driving scenario, the jammers were installed in a vehicle that repeatedly passed the GNSS receivers at a constant speed.  
Session 1 was the walking scenario and lasted from 09:24:01 to 09:35:30. While walking, discrete points on the trajectory were determined about every 5 m with the tachymeter, and each of them was occupied for about 5 s (Figure 7). For jammer 1, the coordinates were determined for each occupation, together with the times of the point determination. The jammer positions are shown graphically in Figure 5b, with the measurement beginning at the northernmost point and ending in the south. After the walking scenario, there were two  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Site** & **Receiver** & **B-Latitude** & **L-Longitude** & **H [m]** \\ \hline
1 & Leica GS18 & 45.56395050\({}^{\circ}\)N & 13.89422284\({}^{\circ}\)E & 434.750 \\
2 & Samsung S20 & 45.56386619\({}^{\circ}\)N & 13.89414673\({}^{\circ}\)E & 434.916 \\
3 & Huawei P40 & 45.56378458\({}^{\circ}\)N & 13.89408466\({}^{\circ}\)E & 435.804 \\
4 & Leica GS18 & 45.563771819\({}^{\circ}\)N & 13.89401580\({}^{\circ}\)E & 435.079 \\
4 & Xiaomi Mi8 & 45.56371192\({}^{\circ}\)N & 13.89400552\({}^{\circ}\)E & 433.894 \\
5 & Xiaomi 11T & 45.56365512\({}^{\circ}\)N & 13.89395938\({}^{\circ}\)E & 435.249 \\
6 & Leica GS18 & 45.56351189\({}^{\circ}\)N & 13.89382173\({}^{\circ}\)E & 435.408 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Receivers’ setup from DOY 263 at the locations shown in Figure 5b.  
Figure 6: (**a**) the walking experiment, in which the jammer was attached to the pole directly under the prism and the position of the jammer was determined by TPS; and (**b**) the driving experiment, in which the jammer was placed in the vehicle.  
accurately in the field. Then, we assumed that all the smartphones had chipsets in the upper left-hand corner.  
For relative double-difference positioning of the smartphones and geodetic devices in static mode, the virtual reference station (VRS) in the Slovenian network of continuously operating reference stations was calculated. The observations were processed using both Leica Infinity, ver. 3.4.3 (Leica Geosystems, Heerbrugg, Switzerland), and RTKLIB software (demo5_b34d) [35; 36] using all available navigation constellations. The settings used in the processing are listed in Table 9. The coordinates collected in the field and calculated afterwards agreed at the cm level. During the jamming sessions, the coordinates for every second were determined for all the GNSS receivers and smartphones to supply information about the possible deviations of the coordinates due to the presence of the jammer.