# The Impact of Eclipsing GNSS Satellites on the Precise Point Positioning
## 3 Results and Discussion
### The Impact of Eclipsing Satellites on GNSS PPP
#### 3.3.2 The Impact on the Positioning Accuracy of the Single-System Kinematic PPP  
Different from the static PPP, the coordinate parameters will be set as the white noise model (or random-walk model in low dynamic environment). The strength of the mathematic model is reduced and more number of visible satellites is required. As shown in Table 6, because the tracked GPS satellites are usually enough, S2 can achieve nearly the same positioning performance as that of S3. Compared with S2, the improvements of S1 and S3 are also trivial. This is mainly because of the decommission of II/IIA satellites and the limited number of the IIF satellites (12 IIF satellites among all 32 GPS satellites). Therefore, the impact of the tracked eclipsing IIF satellites will be weakened. S1 and S3 of the GLONASS-only kinematic PPP can achieve a better accuracy than that of S2. 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. Unlike GPS, the GLONASS GDOP is usually smaller in the high latitude regions (larger than 45\({}^{\circ}\)) than the other regions [40]. Therefore,  
Figure 11: The positioning performance of BDS-only static PPP for three eclipsing strategies (JFNG station, DOY 195 of 2017, the sampling rate is 30 s).  
Figure 12: The phase residuals of: BDS C07 (**a**); and C10 (**b**) with strategy 2 (JFNG station, DOY 195 of 2017, the sampling rate is 30 s).  
deleting the GLONASS eclipsing satellites for the station located in the middle or low latitude may greatly reduce its geometric strength. Three stations, namely RGDG (South 53.79\({}^{\circ}\)), MGUE (South 35.78\({}^{\circ}\)) and AREG (South 16.47\({}^{\circ}\)), with nearly the same longitude are selected. As shown in Figure 13, the positioning performance of GLONASS kinematic PPP is clearly related to the latitude of the station. The positioning performance of S1 and S2 of the station RGDG are nearly the same, however, this is not the case for the station MGUE and AREG. It is apparent to find that deleting eclipsing satellites will not always ensure a better solution, even resulting a worse solution than that of S2. Therefore, the mean improvement for all the stations of S2 is obviously smaller than that of S3. Similar to the BDS static PPP, the eclipsing satellites have the greatest impact on the BDS-only kinematic PPP. Compared with S2, using the modeled attitude can improve the positioning accuracy by about 53.59%, 52.20% and 58.96% in the north, east and up direction, respectively, while deleting BDS eclipsing satellites can improve the accuracy by 29.45%, 36.87% and 42.64% in the north, east and up direction, respectively. This is also because of the long duration of maximum yaw angle differences, large PCO values and the limited number of visible satellites.  
Figure 13: The positioning performance of GLONASS-only kinematic PPP for three eclipsing strategies: (**a**) station RGDG; (**b**) station MGUE; and (**c**) station AREG (DOY 194 of 2017, the sampling rate is 30 s).