## 6 Real Jamming Results Analysis
### Low Jamming Scenario
#### 6.1.1 First Trajectory  
It can be seen from Figures 20a,b and 21a,b that using only the GPS DF signals fails to provide a continuous positioning solution during jamming. By using the GPS TF signals or the GPS TF + Galileo SF signals, the positioning solution is still suffering from discontinuity at some epochs where the number of satellites is less than five, as shown in Figure 22. By adding the Galileo TF signals to the GPS TF signals, the performance of the positioning solution is significantly improved. Additionally, adding the GLONASS SF and DF signals to the GPS TF and the Galileo TF signals improves the performance of the positioning solution. This leads to a smoothed positioning solution, especially during jamming intervals, for the GPS TF + Galileo TF + GLONASS DF-based solution with maximum errors of less than 10 m for both horizontal and vertical positioning components, respectively. From Table 6, adding the Galileo SF signals to the GPS TF signals or adding the GLONASS SF signals to the GPS TF + Galileo TF signals does not improve the positioning solutions for all cases, as the jamming signal is already attacking L1 frequency and degrades the contribution of the included SF signals. Additionally, the root mean square error (RMSE) is improved by about 40% for the horizontal positioning error by using the GPS TF + Galileo TF signals, compared to using only the GPS TF signals. The maximum vertical positioning error decreased dramatically from 163.453 m using the GPS TF signals to 37.169 m using the GPS TF + Galileo TF signals. Moreover, using the GPS TF + Galileo TF + GLONASS DF signals is the only way to have a reliable, accurate, and continuous positioning solution. The RMSE is improved by about 4% and 50% in the horizontal and vertical directions, respectively, 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 decreased from 9.600 m and 37.169 m in the case of using the GPS TF + Galileo TF signals to 5.847 m and 11.220 m in the case of using the GPS TF + Galileo TF + GLONASS DF signals. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Combination**} & \multicolumn{3}{c}{**Horizontal**} & \multicolumn{3}{c}{**Vertical**} \\ \cline{2-7}  & **RMSE** & **Mean** & **Max** & **RMSE** & **Mean** & **Max** \\ \hline GPS DF & 39.087 & 6.750 & 841.198 & 87.420 & 12.630 & 1757.638 \\ \hline GPS TF & 45.413 & 6.217 & 1001.927 & 55.505 & 5.340 & 1272.265 \\ \hline GPS TF + Galileo SF & 3.225 & 3.212 & 4.923 & 2.762 & 2.104 & 15.265 \\ \hline GPS TF + Galileo TF & 1.707 & 0.975 & 7.245 & 3.332 & 2.285 & 13.756 \\ \hline GPS TF+ Galileo TF + GLONASS SF & 2.015 & 1.781 & 11.262 & 2.314 & 1.580 & 18.614 \\ \hline GPS TF + Galileo TF + GLONASS DF & 2.800 & 2.754 & 5.137 & 2.330 & 1.507 & 11.658 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: RMS error, mean, and Max positioning errors with high jamming [second trajectory]. Figure 20: (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]. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Combination**} & \multicolumn{3}{c}{**Horizontal**} & \multicolumn{3}{c}{**Vertical**} \\ \cline{2-7}  & **RMSE** & **Mean** & **Max** & **RMSE** & **Mean** & **Max** \\ \hline GPS DF & 177.205 & 24.096 & 3908.975 & 328.590 & 51.193 & 4711.388 \\ \hline GPS TF & 3.649 & 3.166 & 56.892 & 6.308 & 2.022 & 163.453 \\ \hline GPS TF + Galileo SF & 4.123 & 3.586 & 15.631 & 6.482 & 2.747 & 98.680 \\ \hline GPS TF + Galileo TF & 2.182 & 1.996 & 9.600 & 6.917 & 4.481 & 37.169 \\ \hline GPS TF+ Galileo TF + GLONASS SF & 4.204 & 2.865 & 33.975 & 10.308 & 9.223 & 27.846 \\ \hline GPS TF + Galileo TF + GLONASS DF & 2.089 & 1.937 & 5.847 & 3.454 & 2.810 & 11.220 \\ \hline \hline \end{tabular}
\end{table}