# Characterization of Carrier Phase-Based Positioning in Real-World Jamming Conditions
## 4 Analysis and Results
### Analysis 6: The Network Solution  
The purpose of this analysis is to investigate how jamming of a single reference station impacts end user positioning performance in a network RTK solution. In order to evaluate RTK network performance during jamming, both network fixing ratios (the ratio of integer fixed satellites to the number of tracked satellites) and rover positioning may be investigated. What is of interest is whether the network as a whole (or a group of neighboring stations) will be affected, when one reference station suddenly succumbs to jamming. As previously mentioned, a permanent rover, known as the monitor station, has been established in the TAPAS network, thus it is straight forward to determine the impact on rover positioning during a jamming incident using positioning data from this station. The monitor station, however, was only established in May 2020 and, therefore, of the three cases used here, only jamming Case 1 was observed by the monitor station. For jamming Case 2, no real-time positioning data are available, but the network performance from the incident is logged on the server for evaluation. Owing to the rather light nature of jamming Case 3, and the similarities with Case 1 (in that it is GPS and Galileo L1 jamming), it will be disregarded in this analysis. The monitor station consists of a Septentrio Mosaic multi-constellation, multi-frequency RTK receiver coupled with a Septentrio PolaNt-x MF antenna. The receiver is constantly connected to the TAPAS virtual reference station (VRS) solution, which is transmitting triple frequency GPS, Galileo, and BeiDou data, as well as dual-frequency GLONASS data. The monitor station is located roughly 3.2 km from the nearest reference station (TA06) and, as seen in Figure 1, neither TA03 or TA10 are among the nearest stations. In the positioning solution from the monitor station during Case 1, no discernible impact is seen on the accuracy or precision of the solution. The standard deviation of the relative positioning solution during the Case 1 jamming incident is shown in Table 10 for the three coordinate components, and these are clearly within RTK standards. Figure 16: 3D positioning error for a single- and a dual-frequency GPS + Galileo solution for Case 2, baseline 2 (11 km). Only the solution of the first part of the jamming incident is shown. Unsurprisingly, there is no clear impact, as this solution is a full four constellation and three frequency solution during a single-frequency jamming incident--and it is not even affecting any of the nearest reference stations (only TA03 is affected in Case 1). Despite this, Figure 17 shows that the number of satellites in the positioning solution seemingly drops during the jamming incident, even though jamming affects just 1 reference station in a network of 11. Looking into the network fixing ratio, it is clear that the entire network's ability to fix ambiguities for the Galileo satellites is somehow affected in this period. The beginning of the incident, however, does not fully correlate with the drop-out of Galileo, and neither does a post-processed network solution show any problems on the fixing ratios (except for the jamming-affected station, TA03). Thus, it may be concluded that the drop-out of Galileo satellites was not due to jamming, but rather the previous configurations or the old version of the processing software employed at that time. While jamming Case 2 happened before the monitor station was established, it is still possible to refer to the network fixing rates from the incident. Network fixing rates are continuously logged in real time on the processing server. The fixing rate of the network during jamming Case 2 is shown in Figure 18. It should be noted that the fixing rate becomes heavily affected after 18:30, but this is unrelated to the jamming incident, which ends at 18:18, and thus was not investigated further. In Figure 18, the jamming incident is discernible by small dents at 17:27, 18:07, and again at 18:18.