# A Comprehensive Signal Quality Assessment for BDS/Galileo/GPS Satellites and Signals
## 3 Experiment Results
### Experimental Analysis of Multipath  
Corresponding to Figures 5 and 6, comparisons of multipath values are presented in Figures 8 and 9, respectively. The BDS-3 satellites perform better than BDS-2, and their multipath values no longer tend to vary with the elevation, which may be related to the better multipath resistance of their new modulated signals. In addition, the on-satellite multipath errors that appeared on BDS-2 satellites are no longer present on the BDS-3 satellites. The BDS-3 B2a, GPS L5, and Galileo E5b have significantly smaller multipath errors than other signals.  
In order to more clearly compare the magnitude of multipath values at each signal, the STD values of multipath combinations for each satellite at different signals are shown in Figure 10. The accuracies of BDS-3 B2a, BDS-2 B3I, GPS L5, and Galileo E5b are superior to other signals in their respective systems.  
Figure 6: Time series of CC values for BDS-2 (C5, C6, and C12), Galileo (E12 and E31), and GPS (G15, G11, and G24) satellites at different signals during DOY 134–140 in 2019. Legends B1I (light green), B2I (bright green), and B3I (light blue) are for BDS satellites C5, C6, and C12. Legends E1 (light blue), E5a (light green), E6 (bright green), and E5b (light yellow) are for Galileo satellites E12 and E31. Legends L1 (light blue), L2 (light green), L5 (bright green) are for GPS satellites G15, G11 and G24.  
Figure 7: Comparison of average CC STD values in different stations. The horizontal axis in subfigure (**a**) represents 15 stations with receiver type JAVAD, while that in subfigure (**b**) represents 24 stations with receiver type LEICA, that in subfigure (**c**) represents 29 stations with receiver type SEPT, and that in subfigure (**d**) represents 40 stations with receiver type TRIMBLE. In each subgraph, the 4 panels are for BDS-3 B1I/B3I/B2a, BDS-2 B1I/B2I/B3I, GPS L1/L2/L5, and Galileo E1/E5a/E6/E5b/E5, respectively.  
Figure 8: Multipath values against satellite elevation for BDS-3 C19, C21, C23, and C35 satellites during DOY 134–140 in 2019. MPC stands for Multipath Combination.  
Figure 9: Multipath values against satellite elevation for BDS-2 (C5, C21, and C23), Galileo (E12 and E31), and GPS (G15, G11, and G24) satellites during DOY 134–140 in 2019. Legends BII (light blue), B2I (light green) and B3I (bright green) are for BDS satellites C5, C6, and C12. Legends E1 (light blue), E5a (light green), E6 (bright green), and E5b (light yellow) are for Galileo satellites E12 and E31. Legends L1 (light blue), L2 (light green) and L5 (bright green) are for GPS satellites G15, G11 and G24.  
Similar to the comparison of _C/N0_ and CC values for each station, the STD values of the multipath combinations for each type of receiver at different signals are shown in Figure 11. Similar characteristics can be found, namely that the multipath values have little relationship with the receiver type. Similarly, the Galileo E5 signal exhibits superior performance compared to all other signals, regardless of receiver type.  
Figure 10: STDs of multipath combinations for different satellites. The four panels from top to bottom are for BDS-3, BDS-2, GPS, and Galileo satellites, respectively.