## 5 Real-Time PPP Performance of Smartphone
### Static PPP Performance  
The observations received by the Huawei Mate40, P40 and Novatel receiver on DOY 319 were for the period of 10:00-12:00 UTC. After obtaining the coordinates, they were converted to E, N and U components to evaluate the smartphone positioning performance. Thus, the convergence time and positioning accuracy were used to evaluate the smartphone PPP performance. The convergence is defined as the RMS coordinates being less than 0.3 m for the current and next 20 consecutive epochs. The static positioning experiments were conducted for GPS, BDS, GPS/BDS combination, GPS/BDS/Galileo combination and GPS L1/L5 combination, respectively. The performance differences between single-system and multi-system combined positioning of smartphones and geodetic receiver were compared. The positioning error of static real-time PPP for five combinations using Huawei Mate40, P40 and Novatel receivers in the E, N and U components are presented in Figure 9 (in this figure, HM40, HP40 and DH04 represent Huawei Mate40, Huawei P40 and Novatel receiver, respectively). As can be seen from Figure 9, the positioning errors differences between the smartphone and geodetic receiver are slightly large; the positioning errors for the geodetic receiver are more stable than that of the smartphone because the measurement noise of the geodetic receiver is less than that of the smartphone. For the smartphone real-time static PPP, centimeter-level positioning accuracy can be achieved after convergence. For the Huawei Mate40, the fluctuation of positioning accuracy for the GPS-only and BDS-only solutions is larger, and the convergence times are long. However, compared to GPS-only and BDS-only solutions, the convergence time of the GPS/BDS combination can be improved with 5, 15 and 30 min at the E, N and U components, respectively. For the Huawei P40, compared to GPS-only and BDS-only solutions, the convergence time of the GPS/BDS combination can be shortened, and the convergence time is about 5 min, 30 min and 5 min in the E, N, and U directions, respectively. The convergence time of multi-GNSS real-time static PPP is faster than that of a single system. In total, compared to GPS-only and BDS-only solutions, the positioning accuracy of dual frequency can be improved. The RMS of static real-time PPP positioning accuracy using five combinations for Huawei Mate40, P40 and Novatel receivers in the E, N, and U components are listed in Table 5. As can be seen from the table, the real-time positioning accuracy of the Huawei P40 outperforms the Huawei Mate40 in terms of GPS-only and GPS/BDS combination. The positioning accuracy of the GPS/BDS/Galileo combination is the best among the five combinations, with RMS of 0.09, 0.27 and 0.12 m in the E, N and U components, respectively. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**System**} & \multicolumn{3}{c}{**Mate40 (m)**} & \multicolumn{3}{c}{**P40 (m)**} & \multicolumn{3}{c}{**DH04 (m)**} \\ \cline{2-10}  & **East** & **North** & **Up** & **East** & **North** & **Up** & **East** & **North** & **Up** \\ \hline G & 0.75 & 0.64 & 1.33 & 0.23 & 0.68 & 1.39 & 0.29 & 0.56 & 0.88 \\ C & 0.37 & 0.39 & 0.23 & 0.49 & 0.60 & 0.67 & 0.24 & 0.39 & 0.58 \\ GC & 0.13 & 0.15 & 0.21 & 0.28 & 0.28 & 0.30 & 0.24 & 0.36 & 0.55 \\ GCE & 0.08 & 0.13 & 0.20 & 0.09 & 0.27 & 0.12 & 0.23 & 0.33 & 0.54 \\ G (L1/L5) & 0.07 & 0.13 & 1.13 & 0.19 & 0.61 & 1.03 & 0.24 & 0.52 & 0.80 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: RMS of real-time static PPP accuracy. Figure 9: Real-time static PPP accuracy for Huawei Mate40, P40 and Novatel. For the Huawei Mate40, compared to the GPS-only solution, the positioning accuracy of the GPS/BDS combination was improved from 0.75, 0.64 and 1.33 m to 0.13, 0.15 and 0.21 m in the E, N and U components, respectively, with an improvement of 83.42%, 77.12% and 84.16%, while the improvements are 66.40%, 62.18% and 9.48% compared to the BDS-only solution, respectively.