## 5 Results and Discussion
### Comparison of the Code Bias with Normal Geodetic Antenna  
According to the above analysis, there is a code bias variation of about 0.1-0.2 m in the BDS-3 satellite, which is not uniquely related to the elevation. The observations by the 40-m dish antenna with low noise are better able to reflect the satellite-induced code bias; however, elevation-dependent code bias may be hidden due to the higher noise and lower gain of the normal geodetic antennas for mass-market. The observations in the same arc section of the Xia1 station with the antenna of RINT-8 CH and the receiver of GNSS-GRR from the International GNSS Monitoring & Assessment System (iGMAS) are selected to explore and compare the performance of the code bias for mass users with normal geodetic antennas. The position of the Xia1 station is in Lintong, \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Spink**} & \multicolumn{8}{c}{**RMS (m)**} \\ \cline{2-9}  & **C19** & **C20** & **C21** & **C22** & **C23** & **C24** & **C25** & **C26** \\ \hline B1C\_pilot & 0.083 & 0.036 & 0.046 & 0.042 & 0.026 & 0.058 & 0.032 & 0.041 \\ B1C\_data & 0.085 & 0.037 & 0.051 & 0.045 & 0.042 & 0.068 & 0.045 & 0.052 \\ \hline \multirow{2}{*}{**BRN**} & \multicolumn{8}{c}{**RMS (m)**} \\ \cline{2-9}  & **C27** & **C28** & **C30** & **C32** & **C33** & **C35** & **C37** & **MEAN** \\ \hline B1C\_pilot & 0.043 & 0.050 & 0.033 & 0.035 & 0.046 & 0.036 & 0.066 & 0.045 \\ B1C\_data & 0.048 & 0.060 & 0.036 & 0.037 & 0.054 & 0.042 & 0.073 & 0.052 \\ \hline \end{tabular}
\end{table} 
Table 3: The RMS values of MP combinations tracked by a 40 m dish antenna with the B1C_data and B1C_pilot signal. Figure 8: MP combination time series with respect to elevation for C21/C27/C30 B1C_data and B1C_pilot signal tracked by a 40 m dish antenna. Xi'an and close to that of the 40-m dish antenna, which ensures the consistency of the elevations and satellite terminal errors within the same observation arc. The systematic bias difference between the Xia1 station and 40-m dish antenna can be attributed to antenna and receiver configurations without MP errors of the antenna and receiver resulting from the surroundings. The iGMAS station only tracks the B1C_pilot signal which was used in the section. The sampling interval of observations by the 40-m dish antenna is changed to be the same as that of the Xia1 station for 30 s.  
Table 4 shows the RMS of the MP combination values of each satellite frequency band. The RMS values of the MP combination of Xia1 is about 10 cm for the B1I/B2b/B3I/B2a frequency bands and exceeds 10 cm for the B1C frequency band --larger than that measured by the 40-m antenna. Figure 9 shows the MP combination time series with respect to the elevations of the C21/C24/C27/C28/C37 satellites with obvious elevation-dependent code bias measured by the 40-m antenna, in which the purple line refers to the smooth data for the Xial station. Among the frequency bands of the C21/C24/C27/C28/C37 satellites in Xia1 station, there still exists an elevation-dependent code bias of in the B1I/B1C/B3I/B2a/B2b of C21, B3I/B2a/B2b of C24 and B2b of C28 frequency bands, indicating that the satellite-induced elevation-dependent code bias may also appear in different antennas or receivers. However, no similar variations have been found in the existing research with different antennas or receivers [16; 17; 18] and the systematic variations are observed on the MP combination of B1C due to the signal processing of the receiver [16]. Therefore, more different antennas or receivers are needed to analyze the variation and influence of the BDS-3 satellite-induced code bias.