# Evaluating the Vulnerability of Several Geodetic GNSS Receivers under Chirp Signal L1/E1 Jamming
## 6 Conclusions  
Experiments investigating the impact of low cost L1/E1 jammers on the functioning of several GNSS instruments are complex, largely because they cannot be performed anywhere and at any time. For the purposes of this research, GNSS observations that were acquired from several geodetic GNSS receivers placed at the very same location were simultaneously processed in order to get information about the vulnerability of each specific GNSS geodetic receiver with the knowledge of the relevant authorities. Although the observation plan was prepared with the utmost care, the realisation cannot always be optimal. Legal testing of jamming at the specific time was assured; however, the time of the measurements unfortunately coincided with technical problems with Galileo that occurred in July 2019 due to an outage in the ephemeris provisioning [49]. Therefore, since not all the receivers that were at our disposal for this research could receive Galileo signals, the study was limited to just GPS and GLONASS. Galileo signals were nevertheless received (see Appendix A); however, further computations of the elevations and azimuth due to the lack of the ephemerides presented a problem for the analysis. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**Maximal Error from**} & \multicolumn{2}{c}{**Maximal Error from**} \\  & \multicolumn{2}{c}{**Code Solutions (m)**} & \multicolumn{2}{c}{**Phase Solutions (m)**} \\ \hline
**Receiver Type** & **Horizontal** & **Vertical** & **Horizontal** & **Vertical** \\ \hline Trimble 4000 SSi & 143.67 & 426.69 & 0.025 & 0.060 \\ Trimble R8 & 1.24 & 1.45 & 2.251 & 3.128 \\ Trimble R10 & 2.91 & 4.38 & 0.036 & 0.085 \\ Trimble R8s & 772.01 & 1426.60 & 0.237 & 0.483 \\ Javad Triumph-VS & 2.92 & 7.16 & 0.096 & 0.127 \\ Javad Triumph-LSA & 1.71 & 3.72 & 0.092 & 0.496 \\ Leica GS18 & 2.45 & 2.10 & 0.057 & 0.077 \\ Leica GS07 & 2.31 & 2.50 & 0.066 & 0.163 \\ Leica GS15 & 4.29 & 4.52 & 0.070 & 0.095 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Quality of positioning: maximal horizontal and vertical deviations in coordinates in the horizontal plane and in heights during static and kinematic jammings. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Receiver Type** & **Any Solution** & **Phase Fix** & **Horizontal \textless{} 1 cm** & **Vertical \textless{} 2 cm** \\ \hline Trimble 4000 SSi & 88\% & 83\% & 51\% & 68\% \\ Trimble R8 & 99\% & 98\% & 45\% & 73\% \\ Trimble R10 & 52\% & 49\% & 42\% & 48\% \\ Trimble R8s & 81\% & 55\% & 29\% & 33\% \\ Javad Triumph-VS & 100\% & 89\% & 41\% & 71\% \\ Javad Triumph-LSA & 100\% & 91\% & 50\% & 77\% \\ Leica GS18 & 99\% & 99\% & 61\% & 82\% \\ Leica GS07 & 94\% & 94\% & 57\% & 76\% \\ Leica GS15 & 91\% & 89\% & 59\% & 79\% \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Percentage of the successful ambiguity fixing from 8:20 to 10:00 UTC, i.e., during static and kinematic jammings. That being said, an analysis of the effect of jammers on the geodetic positioning instruments was carried out. It has been shown that all the instruments should be able in principle to detect the presence of a jammer, and to some extent, even localise its position. Applying the distance evaluation procedure, we get the most accurate solutions using the L2 band C/N\({}_{0}\) data from Trimble 4000 SSi. Leica GS07 results are more significant in bilateration according to the Leica GS15 receiver. It was also shown that the jammer significantly deteriorated the performance of the receivers by means of position determination. When strong jamming was taking place (jammer in the receiver's vicinity), virtually all the instruments were unable to obtain a fix (a phase solution) at least for some time. However, both the Javads and Leica GS18 performed slightly better, providing at least a code solution all the time. On the other hand, Trimble R10, and to some extent Trimble R8s, had a significant suppression time where they provided no solution at all.