# Characterization of Carrier Phase-Based Positioning in Real-World Jamming Conditions
## 4 Analysis and Results  
The purpose of the following analyses is to characterize the performance that can be obtained using a jammed reference station receiver for an RTK solution. Thus, the following six analyses (as listed in Table 2) will be used to determine how the best PPK positioning accuracy is achieved for the three selected cases.  
All analyses, except number 6, will be based on single-baseline PPK solutions with the jammed receiver as the base. The reference stations used as rover receivers are free from jamming. For all analyses, forward, kinematic processing is used, in order to have the results resemble actual RTK as much as possible.  
The various baselines used in the analyses are presented in Table 3. The fourth baseline of Case 2 is a baseline to a permanent reference station outside the TAPAS network, which is used as an extreme case for baseline solutions.  
In all cases, an elevation mask of 10 degrees is used, while the receivers themselves (as previously mentioned) use a 20 dBHz C/N\({}_{0}\) mask. Ionospheric processing and tropospheric error states are disabled, and broadcast orbits are used for all relevant analyses because baselines are generally short.  
Finally, Analysis 6 will focus on the impact to the TAPAS network solution by assessing network performance during the incidents. This is possible by using TAPAS network logs,  
\begin{table}
\begin{tabular}{l l l l} \hline \hline \multirow{2}{*}{\#} & **Purpose of Analysis Is** & **Cases** & **Processing Software** \\  & **to Determine:** & & \\ \hline \multirow{2}{*}{1} & Performance of receiver tracking & \multirow{2}{*}{Case 1, Case 2, Case 3} & RTKlib \\  & during jamming & & \\ \multirow{2}{*}{2} & Code vs. carrier phase & \multirow{2}{*}{Case 3} & RTKlib \\  & positioning performance & & \\ \multirow{2}{*}{3} & Effects of using & \multirow{2}{*}{Case 1, Case 2} & Inertial Explorer \\  & multiple constellations & & \\ \multirow{2}{*}{4} & Significance of baseline length & \multirow{2}{*}{Case 2} & Inertial Explorer \\  & Impacts of a dual-frequency solution & & \\ \multirow{2}{*}{6} & Impact of single-station jamming on & \multirow{2}{*}{Case 1, Case 2} & Inertial Explorer \\  & network RTK performance & & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Analyses of the jammed data.  
Figure 6: GPS L1 C/N\({}_{0}\) values for the Case 3 jamming incident; an approximately 12 min event affecting only the L1 band.  
network post processing, as well as the positioning solution of the network monitoring station previously mentioned (and as shown in Figure 1).  
RTKlib (version 2.4.3 demo5 b33e) is used for Analyses 1 and 2 thanks to its ease of use and the fact that it provided plot options otherwise unavailable to us.  
Commercial postprocessing software, Inertial Explorer (IE) version 8.70.8722, is used for PPK solutions in Analyses 3, 4, and 5. This ensures coherency in positioning solutions, and IE is well-renowned for its accurate solutions.  
The network evaluation in Analysis 6 is done with the GNSMART 2.70 software by Geo++, which also processes the TAPAS network solution.  
Owing to processing issues with four-constellation solutions in IE, it was chosen not to include BeiDou in this particular investigation. Instead, as will be clear, the results are based on GPS, GLONASS, and Galileo constellations. While there are reasons to believe that the inclusion of BeiDou would improve positioning performance (namely BeiDou B1I center frequency, 1561.098 MHz, is slightly offset from GPS L1, which sees the majority of the jamming [8]), there is no reason to believe that it would affect the general conclusions of this paper.  
Further, it should be noted that Inertial Explorer must include GPS in its PPK solution and, as such, solutions without GPS were not evaluated.