## 5 Simulated Jamming Results Analysis
### Low jamming Scenario
#### 5.1.1 First Trajectory  
It can be seen from Figures 8 and 9 that using only GPS signals, either dual-frequency (DF) or triple-frequency (TF) signals, cannot maintain a reliable poisoning solution during the jamming interval that is indicated as a grey-hatched region. The horizontal positioning error exceeds 10 m in the case of using GPS DF signals and reaches a maximum of 8 m during the jamming interval using the GPS TF signals, as shown in Figure 8a,b. The same behavior is depicted for the vertical positioning error, showing errors exceeding 20 m and 15 m for the GPS DF and GPS TF-based solutions, respectively, as in Figure 9a,b. By  
Figure 7: Anechoic chamber including both Tx and Rx antennas.  
adding the Galileo SF signal only to GPS TF signals, the performance is similar to the GPS TF case, as shown in Figures 8 and 9. This is because the jamming is attacking the GPS L1 frequency, which is the same as the Galileo E1 frequency, and adding just E1 signals cannot play a major role in improving the performance during jamming. After adding the Galileo TF signals to the GPS TF signals, the positioning solution is significantly improved. Additionally, positioning errors are less than 4 m for both horizontal and vertical components. Moreover, adding GLONASS SF and DF signals to GPS TF and Galileo TF signals improved the performance of the positioning solution. This led to a smoothed positioning solution, especially during jamming intervals, for the GPS TF + Galileo TF + GLONASS DF solution, with a maximum error of about 3 m and 4 m in the horizontal and vertical directions, respectively.  
As shown in Figure 10, the number of visible satellites during the jamming period increased from 5 satellites using GPS TF signals to 10 satellites by adding Galileo signals and 20 satellites by adding GLONASS signals, which is reflected in the positioning solution performance as previously indicated.  
Figure 8: (**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].  
Table 2 shows the statistical analysis of the first trajectory under low jamming conditions. By using the GPS TF signals, the accuracy of the positioning solution was improved compared to the GPS DF-based solution. The root mean square error (RMSE) is improved by about 23% in the horizontal position component and 55% in the vertical position component, respectively, using GPS TF + Galileo TF signals, compared to using only GPS TF signals. Additionally, using GPS TF + Galileo TF + GLONASS SF signals provides similar positioning accuracy compared to the GPS TF + Galileo TF-based solution. However, by using the GLONASS TF signals instead of GLOANSS SF signals, the RMSE improved by about 11% and 37% in the horizontal and vertical directions, respectively, compared to the GPS TF + Galileo TF-based solution. One more advantage of the inclusion of multi-frequency multi-constellation GNSS signals in the positioning solution estimation is the bounding of the maximum (Max) positioning errors. As shown in Table 2, the horizontal Max error decreased from 1141.527 m using the GPS DF signals to 3.074 m using the GPS TF + Galileo TF + GLONASS DF signals, and the vertical Max error decreased from 3283.053 m using the GPS DF signals to 4.024 m using the GPS TF + Galileo TF + GLONASS DF signals.  
Figure 9: (**a**) Vertical positioning error for different GNSS signal combinations [first trajectory]. (**b**) Zoomed view of vertical positioning error for different GNSS signal combinations [first trajectory].