# Real-Time Precise Point Positioning during Outages of the PPP-B2b Service
## 3 Experiments and Results  
### Continuity of B2b Corrections  
#### 3.1.1 Jumps in Orbit Corrections  
Figure 2 presents the time series of the orbit corrections on DOY 192 in 2022. For the BDS-3 satellites, the correction values in the radial, along-, and cross-track directions were in the ranges of 0.05 m, 0.1 m, and 0.1 m, respectively; for the GPS satellites, the correction values in the radial, along-, and cross-track directions were in the ranges of 0.5 m, 2.0 m, and 1.0 m, respectively, which are much larger than those of BDS-3. This is because the CNAV1 broadcast ephemeris used to calculate the BDS-3 satellite orbit has a higher accuracy than the LNAV broadcast ephemeris used to calculate the GPS satellite orbit [19]. As shown in Figure 2, the orbit corrections of both BDS-3 and the GPS satellites contained frequent jumps. For the BDS-3 MEO satellites, the mean magnitudes of the jumps were 0.017 m, 0.033 m, and 0.029 m in the radial, along-, and cross-track directions, respectively; for the BDS-3 IGSO satellites, the mean magnitudes of the jumps were 0.018 m, 0.039 m, and 0.033 m in the radial, along-, and cross-track directions, respectively; for the GPS satellites, the mean magnitudes of the jumps were 0.039 m, 0.189 m, and 0.081 m in the radial, along-, and cross-track directions, respectively. Due to the existence of these frequent jumps, the orbit corrections were divided into several consecutive arcs. Figure 3 shows the number of orbit arcs with different durations in the studied period. For the BDS-3 satellites, most arcs were over 30 min, while for the GPS satellites, most were within 20 min. It should be noted that the BDS-3 IGSO satellite orbit corrections were more frequent piecewise variations than the BDS-3 MEO satellite orbit corrections, and their continuity was worse.  
The jump phenomenon of the orbit corrections during DOY 192-198 in 2022 was further investigated. For the BDS-3 MEO satellites, the mean values of the jumps in the radial, along-, and cross-track directions during this period were 0.018 m, 0.047 m, and 0.042 m, respectively; for the BDS-3 IGSO satellites, the mean values of the jumps in the radial, along-, and cross-track directions during this period were 0.019 m, 0.058 m, and 0.055 m, respectively, which are slightly worse than those of the BDS-3 MEO satellites. For the orbit corrections of the GPS satellites, the mean values of jumps in the radial, along-, and cross-track directions during this period were 0.042 m, 0.211 m, and 0.089 m, respectively, which are larger than those in the BDS-3 satellite orbit corrections. In addition, the average number of consecutive periods for the orbit corrections during this period was also studied. The orbit corrections of the BDS-3 MEO satellites usually contained approximately 11 jumps daily, and approximately 41% of the consecutive periods had a duration of shorter than 30 min; for the BDS-3 IGSO satellites, the orbit corrections usually contained approximately 26 jumps daily, and approximately 62% of the consecutive periods had a duration of shorter than 30 min. The orbit corrections of the GPS satellites contained approximately 17 jumps daily, and approximately 60% of these arcs lasted for less than 30 min. These results show that jumps in BDS-3 IGSO satellite orbit corrections were the most frequent, followed by GPS satellite orbit corrections. In contrast, the jumps in the BDS-3 satellite orbit correction were less frequent, but they also affect its continuity. It is the presence of these frequent jumps that makes the orbit prediction very difficult and unreliable.  
Figure 3: Number of consecutive periods for orbit arcs of the BDS-3 and the GPS satellites with different lengths of time on DOY 192 in 2022. Different colors represent different continuous time periods.  
Figure 2: Time series of the orbit corrections of the BDS-3 and the GPS satellites in the radial, along-, and cross-track directions on DOY 192 in 2022.