# Analyses of GLONASS and GPS+GLONASS Precise Positioning Performance in Different Latitude Regions
## 4 Results and Discussion
### Data Quality  
The DI rate, MP1, MP2, SN1 (the SNR of L1), and SN2 (the SNR of L2) of GPS and GLONASS observations for each station are calculated and presented in Figure 3. The mean value of each indicator is listed in Table 5, where G and R denote GPS and GLONASS, respectively.  
\begin{table}
\begin{tabular}{l l l} \hline \hline
**Station Name** & **Receiver Type** & **Antenna + Radome Type** \\ \hline BRAZ & TRIMBLE NETR9 & TRM57971.00 NONE \\ CHPI & SEPT POLARX5 & TPSCRG3 NONE \\ SALU & TRIMBLE NETR9 & TRM115000.00 NONE \\ SAVO & TRIMBLE NETR9 & TRM115000.00 NONE \\ SPTU & TRIMBLE NETR9 & TRM57971.00 NONE \\ TOPL & TRIMBLE NETR9 & TRM115000.00 NONE \\ UFPR & TRIMBLE NETR9 & TRM115000.00 NONE \\ \hline \hline \end{tabular}
\end{table}
Table 4: The GNSS receivers and the antenna + radome types of the low latitude stations.  
Figure 2: The IGS tracking stations of the high (red triangle), middle (green triangle), and low latitude networks (blue triangle).  
The data integrity rate of GLONASS in 21 stations of the 3 networks is lower than that of GPS, as is evident in Figure 3. As shown in Table 5, the calculated average data integrity rates of GLONASS in the three networks are 82.37%, 83.46%, and 81.33%, respectively, significantly lower than those of GPS with 94.33%, 96.11%, and 94.81%, respectively.  
The MP1 and MP2 of GPS presented similar performance to that of GLONASS in the high latitude network. However, the MP1 and MP2 of GPS in the middle latitude network are smaller than those of GLONASS in most stations, except station HERT. By contrast, the MP1 and MP2 of GLONASS in the low latitude network are smaller than those of GPS. The calculated average value of MP1 and MP2 in Table 5 indicates similar results, but the differences in MP1 and MP2 between GPS and GLONASS are insignificant.  
The difference in SN1 between GPS and GLONASS is minor in the three networks, except SOD3 and SVTL in the high latitude network and WARN in the middle latitude network. The SN2 of GLONASS is significantly better than that of GPS in the high and low latitude networks and similar to that of GPS in the middle latitude network.  
Among the 21 tracking stations, however, the data quality of SALU in the low latitude network is significantly worse than other stations. The DI rate of SALU is 84.3% for GPS  
Figure 3: The results of the data quality check.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**RegionIndicator** & \multicolumn{2}{c}{**DI (\%)**} & \multicolumn{2}{c}{**MP1 (m)**} & \multicolumn{2}{c}{**MP2 (m)**} & \multicolumn{2}{c}{**SN1 (dB)**} & \multicolumn{2}{c}{**SN2 (dB)**} \\ \cline{2-10} \multicolumn{1}{c}{**G**} & **R** & **G** & **R** & **G** & **R** & **G** & **R** & **G** & **R** \\ \hline High latitude network & 94.33 & 82.37 & 0.47 & 0.48 & 0.45 & 0.39 & 6.56 & 7.12 & 5.33 & 6.88 \\ \hline Middle latitude network & 96.11 & 83.46 & 0.39 & 0.46 & 0.39 & 0.43 & 7.02 & 7.20 & 6.35 & 6.76 \\ \hline Low latitude network & 94.81 & 81.33 & 0.72 & 0.53 & 0.48 & 0.44 & 6.72 & 6.59 & 4.92 & 6.32 \\ \hline \hline \end{tabular}
\end{table}
Table 5: The mean value of each data quality indicator in the three networks.  
and 71.6% for GLONASS. The MP1 of SALU is up to 0.99 m and 0.89 m for GPS and GLONASS observations, respectively, much larger than those calculated average values, 0.39 m and 0.46 m for GPS and GLONASS. The MP2 of SALU presented similar results as that of MP1.