# Evaluating the Vulnerability of Several Geodetic GNSS Receivers under Chirp Signal L1/E1 Jamming
## 3 Setup and Measurement Campaign
### GNSS Jammer Characterisation  
For the benefit of the experiment, a commercially available in-car jammer was used. With regard to [PERSON] et al. (2019), it was a sub-miniature version A (SMA) unlabelled jammer L1/E1 jammer, with no manufacturer's data, powered by a battery, its external antenna with omnidirectional radiation pattern was connected through a SMA connector (see Figure 3), which emitted a single saw-tooth chirp signal, according to References (K  
occupation, two 3-minute jammings were performed, where the jammer was first placed vertically and then in a horizontal position. Several minutes of non-interruption were conducted between each successive session.  
Experiments involving jamming with the static position of the jammer at the specific point were conducted first; namely, two 3-minute jammings were performed at each of the positions indicated by J1, J2, J3 and J4 (Table 3), which incorporated approximate jammer-receiver distances and the start/end times of the static jamming.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Point Name** & **B-Latitude** & **L-Longitude** & **H [m]** \\ \hline J1 & 45°33′49.06956”N & 13°53′38.52143”E & 435.484 \\ J2 & 45°33′48.18814”N & 13°53′39.88645”E & 435.214 \\ J3 & 45°33′47.62954”N & 13°53′42.58632”E & 433.616 \\ J4 & 45°33′47.53317”N & 13°53′45.21659”E & 433.911 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Position of the jammer in static mode (3-minute jammings, where the jammer remained fixed in a certain position). Heights H were acquired from the ellipsoidal heights by using the SLO_VRP2016/Koper geoid model.  
Figure 4: Pre-planned measurement scenarios (own study).  
Figure 5: Location of the most distant two-way points (\(A\) and \(\mathcal{C}\)) for kinematic experiments (green), location of the receivers (\(B\)) in red and static positions of the jammer (J1, J2, J3 and J4) in yellow (own study).  
Additionally, kinematic tests were performed (Figure 6), whereby a jammer was placed in a vehicle that moved back and forth between points \(A\) and \(C\) and passed the receivers' location at different speeds several times, namely 30 km/h, 60 km/h and 90 km/h. Several tests were performed at the specific speed of the vehicle. The maximum distances between the jammer and the GNSS instruments were about 400 m (between \(A\) and \(B\), as well as between \(B\) and \(C\)). The speed of the vehicle and the moment the vehicle passed the instruments are shown in Table 4. Jammer localisation relies on lateration using the best estimations of the distance from the pairs of synchronized geolocated GNSS receivers, as presented on Figure 6.  
\begin{table}
\begin{tabular}{c c} \hline \hline \multirow{2}{*}{**Speed of the Vehicle**} & \multicolumn{2}{c}{**Time at Which the Vehicle**} \\  & **Passed the Instruments (UTC)** \\ \hline
30 km/h & 09:42:48 \\
30 km/h & 09:45:11 \\
30 km/h & 09:46:58 \\
60 km/h & 09:50:28 \\
60 km/h & 09:51:40 \\
80 km/h & 09:53:09 \\
90 km/h & 09:54:40 \\
90 km/h & 09:56:17 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Jammer’s kinematic disturbances (jammer in the vehicle).  
Figure 6: The principle of localising of the moving jammer in a vehicle by an array of GNSS receivers (own study).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**Distance of**} & **Point of the** & **Polarisation of the** & **Start and End Times** \\
**Jammer Instruments** & **Jammer’s Location** & **Jammer** & **of Jamming (UTC)** \\ \hline
12 m & J1 & Vertical & 08:37:21-08:40:37 \\  & & Horizontal & 08:41:11–08:44:10 \\
50 m & J2 & Vertical & 08:53:51–08:56:54 \\  & & Horizontal & 08:57:25–09:00:19 \\
100 m & J3 & Vertical & 09:03:03–09:06:16 \\  & & Horizontal & 09:07:28–09:10:34 \\
160 m & J4 & Vertical & 09:13:44–09:17:36 \\  & & Horizontal & 09:18:09–09:20:58 \\
12 m & J1 & Vertical & 09:24:01–09:24:23 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Static positions of the jammers and times of the 3-minute jammings.