## 5 Simulated Jamming Results Analysis
### High jamming Scenario
#### 5.2.1 First Trajectory  
As in the low jamming scenario, the jamming signal was inserted between minutes 14 and 16 of the logged data. With the high jamming, the GPS DF-based positioning solution fails to provide a reliable continuous positioning solution, as indicated in Figures 14 and 15. Additionally, by using the GPS TF signals, the resultant solution has continuous behavior but with large horizontal and vertical positioning errors that exceed 10 m and 20 m, respectively, as shown in Figures 14b and 15b. By using the GPS TF + Galileo SF signals, the positioning solution still suffers from discontinuity during jamming intervals. Additionally, by using the GPS TF + Galileo TF, or the GPS TF + Galileo TF + GLONASS SF, the positioning solution shows continuous behavior. However, it still suffers from large spikes that exceed the 10 m level for both the horizontal and vertical components, respectively, as shown in Figures 14b and 15b. By using all available GNSS signals, namely the GPS TF + Galileo TF + GLONASS DF signals, the positioning solution maintains continuous and reliable positioning performance. As shown in Figure 16, adding the GLONASS signals is the only case that offers a sufficient number of visible GNSS satellites to provide a reliable and continuous positioning solution. From Table 4, there are three main findings. The former is that adding only the Galileo SF signals to the GPS TF signals does not improve the positioning accuracy due to the high jamming level on the L1 frequency. Second, adding the GLONASS SF to both the GPS TF signals and the Galileo TF does not provide better positioning accuracy compared to using the GPS TF + Galileo TF signals. The latter, using the GPS TF + Galileo TF + GLONASS DF combination, is the only way to have a reliable, accurate, and continuous positioning solution under high jamming. Additionally, the root mean square error (RMSE) is improved by about 52% and 50% in the horizontal and vertical positional directions, respectively, by using the GPS TF + Galileo TF signals, compared to using only the GPS TF signals. Moreover, the RMSE is improved by about 22% in the horizontal positional direction by using the GPS TF + Galileo TF + GLONASS DF signals, compared to using the GPS TF + Galileo TF signals. The maximum horizontal and vertical positioning errors dramatically decreased from 28.611 m and 94.982 m in the case of using the GPS TF signals to 3.347 m and 11.363 m in the case of using the GPS TF + Galileo TF + GLONSS DF signals. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Combination**} & \multicolumn{3}{c}{**Horizontal Error**} & \multicolumn{3}{c}{**Vertical**} \\  & **RMSE** & **Mean** & **Max** & **RMSE** & **Mean** & **Max** \\ \hline GPS DF & 2.994 & 2.949 & 9.882 & 3.264 & 2.734 & 17.911 \\ \hline GPS TF & 3.112 & 3.084 & 6.139 & 3.103 & 2.173 & 16.388 \\ \hline GPS TF + Galileo SF & 3.154 & 3.138 & 4.914 & 2.545 & 2.128 & 22.633 \\ \hline GPS TF + Galileo TF & 1.810 & 1.544 & 4.517 & 2.163 & 1.647 & 10.969 \\ \hline GPS TF+ Galileo TF + GLONASS SF & 1.243 & 1.024 & 4.390 & 3.163 & 2.280 & 13.842 \\ \hline GPS TF + Galileo TF + GLONASS DF & 0.477 & 0.391 & 2.596 & 1.394 & 1.067 & 6.393 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: RMS error, mean, and Max positioning errors with low jamming [second trajectory]. Figure 14: (**a**) Horizontal positioning error for different GNSS signal combinations [first trajectory]. (**b**) Zoomed view of horizontal positioning error for different GNSS signal combinations [first trajectory]. [first trajectory]. Figure 15: _Cont._  
Figure 16: Number of visible satellites for different GNSS signal combinations [first trajectory].