## 5 Results and Discussion  
This part analyzed and discussed the results. Figure 3 shows the time series of the MP combination values and elevations, in which the black line represents elevations, and the violet, red, yellow, blue, and orange points represent the MP combination values of the B1I, B1C, B2a, B2b, and B3I frequency bands, respectively. In the section, the B1C\({}_{\text{-}}\)pilot signal is used as B1C. The MP combination values of the BDS-3 satellite signals vary a little and concentrated in a range of about 0.2 m, which is smaller compared with BDS-2 satellites. From the relationship between elevation and MP combination values, the MP combination values varies with satellite elevation overall, but the variation is not the same for different satellites. Obviously, MP combination has the largest value when the satellite elevation is less than 30\({}^{\circ}\). The variation of MP combination values is different for available signal bands. In order to further analyze the difference in the code bias of the different frequency bands, Figure 4 shows the root mean square (RMS) values of the MP combination value of all frequency bands in which the last data \"MEAN\" refers to the RMS values of all satellites.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Frequency Band** & **Notation** & **Formula** \\ \hline B1I & M1 & \(P_{M1}-\frac{f_{M2}^{2}+f_{M5}^{2}}{f_{M3}^{2}-f_{M5}^{2}}L_{M1}+\frac{2f_{M5 }^{2}}{f_{M1}^{2}-f_{M5}^{2}}L_{M5}\) \\ B2b & M2 & \(P_{M2}-\frac{f_{M2}^  
The RMS value of MP combination values of the frequency bands is noticeably small about 0.05 m but B1I in about 0.1 m, which indicates that MP error resulting from the station surroundings can be ignored and any systematic bias remaining in the MP observations for the experiment can be safely attributed to the satellite or receiver configuration for the 40 m dish antenna [15]. From the overall results, the MP time series of the old signal B3I is the most stable, showing better MP mitigation performance. The MP combination value of the B1I frequency band has the largest RMS value, indicating the weakest anti-MP ability. The B1I signal experiences interference by the B1A signal due to the overlapping of the B1A and BII spectra of the BDS-3 satellite signal, leading to poor signal quality for B1I. The magnitudes of the MP and noise are related to the observed chip rate [27]. The MP mitigation of the B2 signal is better than that of the B1 signal, since the B2 signal has a higher code rate than the B1 signal does; however, the MP time series stability of the B2 signal does not show better performance than that of the B3I signal, although QPSK is more resistant to MP issues than BPSK is.  
Figure 4: The root mean square (RMS) values of MP combinations tracked by a 40-m dish antenna for each of the BDS-3 satellite frequency bands observed.  
Figure 3: Time series of the MP combinations values and elevations tracked by the 40 m dish antenna for each observed BDS-3 frequency band. The black line represents the elevation, and the violet, red, yellow, blue, and orange points represent the MP combination values of the B1I, B1C, B2a, B2b, and B3I frequency bands, respectively.