# Evaluating the Vulnerability of Several Geodetic GNSS Receivers under Chirp Signal L1/E1 Jamming
## 5 Data Analysis, Results and Discussion
### Positioning Results
Since this is the only such event during this jamming campaign, it is not necessary the case that Trimble R8s is the only instrument that can be affected in such a manner. Furthermore, it is not clear whether this event was isolated or if it should be considered a deficiency of the instrument itself. The authors intend to carry out some further research in this area in the near future. Another Trimble instrument that did not handle the jamming well was Trimble R8. There were some points that were reported as a phase fix but differed by a few metres from the exact position (see Figure 13). However, those points were isolated in the sense that the wrong fix lasted for a single acquisition only and returning to within normal values afterwards. Figure 10: Position discrepancies for the involved instruments: (**a**) Trimble 4000 SSi, (**b**) Trimble R8, (**c**) Trimble R10, (**d**) Trimble R8s, (**e**) Javad Triumph-VS, (**f**) Javad Triumph-LSA, (**g**) Leica GS18, (**h**) Leica GS07, and (**i**) Leica GS15 in the region up to 5 cm. Annotations P and C mean phase fix and code solution respectively. The grey regions are the intervals where the instruments did not report any position. The time origin was set to 08:20 UTC time. Code solutions mostly fall outside of the plotting region and are thus not shown. Figure 11: Vertical and horizontal errors during jamming for the Trimble R10 receiver. The time origin was set at 08:20 UTC time. The annotations P and C indicate the type of solution used, namely phase and code, respectively. The grey region represents the interval when no position was given from the receiver (own study). Figure 12: A zoomed area of the vertical and horizontal discrepancies during the dynamic jamming for the Trimble R8s receiver. W stands for the widelane ambiguity calculation. Note the wrong fixing in the interval from 87 to 90 min from the beginning of the experiment (08:20 UTC) (own study). Returning back to the discussion of GLONASS reception, it seems that the two Javad instruments, namely Javad Triumph-LSA and Javad Triumph-VS, were best able to manage data from the GLONASS satellites. The carrier-to-noise ratio (C/N\({}_{0}\)) for Javad Triumph-VS and Leica GS18 can be seen in Figure 14. The former had stronger signals of about 10 dBHz and did not manifest such big drops. Although none of the instruments were able to get a phase fix from those, they were able to keep a code solution that enabled them to recover to the phase fix faster after the jamming ended. In principle, the following instruments were able to receive the Galileo signal: Trimble R10, Leica GS15, Leica GS18, Javad Triumph-LSA and Javad Triumph-VS (see Appendix A). The Javad receivers obviously cancelled the Galileo signal reception due to a failure of Galileo. As a result of the problem with the operation of Trimble R10, which also provided BeiDou signals, it was not possible to provide a final analysis for this navigation system. It can be seen that the received Galileo signals, interestingly, were not as disturbed as those of the GPS, although they shared the same frequencies. When comparing Leica GS15 and Leica GS18 in terms of Galileo signals, a significant improvement  
Figure 14: Carrier-to-noise ratio (C/N\({}_{0}\); denoted: CNR) for **(a)** Javad Triumph-VS and **(b)** Leica GS18 during strong jamming (09:38 till 09:40). Note that only GLONASS satellites were received in the meantime (the assignation with the letter R). The elevation was also plotted in order to get rid of its effects. The lowest levels of R24 could be attributed to malfunctioning since the satellite shut down shortly after (own study). Figure 13: Discrepancies of the reported position for Trimble R8 (note the zoomed scale). See Figure 12 for a detailed description of the annotations. Those points that are above 1 m and reported as a phase fix were particularly problematic (own study). could be seen in the operation of the newer Leica GS18.