# The Impact of Eclipsing GNSS Satellites on the Precise Point Positioning
## 4 Conclusions  
The attitudes of GNSS satellites are the critical information for GNSS precise point positioning, especially when the orbit products are referred to the center of mass. After monitoring the sun angles and the orbital angles for all GNSS satellites, it has been found that 18 satellites are in eclipse in July 2017. The maximum yaw angle differences and the duration of maneuver for these satellites are analyzed. Datasets collected from 65 globally distributed MGEX stations in July 2017 are selected to analyze the influences of the eclipsing satellites on the single-system and multi-system PPP. The positioning results of three eclipsing strategies, including deleting eclipsing satellites (S1), always using nominal attitudes (S2) and using modeled attitudes (S3), are compared. The results show that the influences of \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Constellation**} & \multirow{2}{*}{**Duration**} & \multicolumn{4}{c}{**Static**} & \multicolumn{4}{c}{**Kinematic**} \\ \cline{3-8}  & & **S1** & **S2** & **S3** & **S1** & **S2** & **S3** \\ \hline \multirow{4}{*}{G} & 30 & 72.48\% & 73.06\% & 73.65\% & 35.69\% & 36.69\% & 37.47\% \\  & 60 & 95.37\% & 95.88\% & 96.34\% & 74.82\% & 75.83\% & 77.14\% \\  & mean & 33.02 & 32.63 & 32.35 & 55.54 & 54.97 & 53.71 \\ \hline \multirow{4}{*}{GR} & 30 & 94.21\% & 94.26\% & 94.36\% & 84.65\% & 83.91\% & 84.65\% \\  & 60 & 99.75\% & 99.75\% & 99.80\% & 98.68\% & 98.73\% & 98.78\% \\  & mean & 23.82 & 23.89 & 23.68 & 28.21 & 28.47 & 28.15 \\ \hline \multirow{4}{*}{GREC} & 30 & 96.40\% & 96.80\% & 96.70\% & 92.56\% & 92.25\% & 92.98\% \\  & 60 & 99.85\% & 99.99\% & 99.99\% & 99.85\% & 99.80\% & 99.85\% \\ \cline{1-1}  & mean & 22.11 & 21.76 & 21.95 & 24.94 & 24.97 & 24.81 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: The average convergence time (minute) and the percentage of convergence under different session length (30 min and 60 min). Figure 15: The positioning performance of GR kinematic PPP for three eclipsing strategies. (Station AREG, DOY 194 of 2017, the sampling rate is 30 s). non-nominal attitudes are related to the magnitude of the PCO values, maximum yaw angle differences, the duration of maneuver, the value of the sun angle and the satellite geometric strength. For GPS-only static or kinematic PPP, the accuracy improvement of S1 and S3 is non-vital. This is because: (1) the GPS IIA satellites are decommissioned from current GPS constellation; (2) the PCO values of IIR satellites are nearly zero; and (3) the number of visible IIF satellites for one station is limited. Due to the large PCO values and the long durations of the GLONASS satellites shadow crossing (54 min for GLONASS satellites), S1 and S3 of the GLONASS-only PPP can achieve a better accuracy than that of S2. For GLONASS-only static PPP model, the improvements of S1 are 8.60%, 9.92% and 4.77% in the north, east and up direction, while the improvements of S3 are 11.20%, 12.3% and 6.43%, respectively. For GLONASS-only kinematic PPP model, the improvements of S1 are 0.12%, 2.41% and 5.06% in the north, east and up direction, while the improvements of S3 are 11.54%, 10.23% and 11.56%, respectively. Because the inconsistency of the modeled attitudes of GALILEO FOC satellites and the underlying attitudes in the precise clock products, using official attitude will result in a slightly worse solution than that of the nominal attitude. Because of the long duration of maximum yaw angle differences, large PCO values and the limited number of visible satellites, both the BDS-only static and kinematic PPP using the modeled attitudes can greatly improve the positioning accuracy. The improvements of S3 for BDS-only static PPP are about 34.99%, 38.34% and 22.39% in the north, east and up direction, while for BDS-only kinematic PPP are about 53.59%, 52.20% and 58.96%, respectively.