## 3 Results
### Data Preparation  
We chose the data collected from two stations, CUTB and CUTC, at Curtin University. As for GPS, we selected two days, 30 April and 1 May 2022, and for BDS, we selected eight days, 30 April to 7 May 2022. The raw data were with a sample rate of 1 Hz, which was helpful to improve the reliability of cycle slip detections. Recall that the relative field antenna calibration is challenged by the south hole (at the southern hemisphere). To simulate a data collection session where both antennas were horizontally rotated 180\({}^{\circ}\), we transformed the azimuths of all satellites on the first day, 30 April 2022, with 180\({}^{\circ}\) increments. Therefore, the two data collection sessions for GSP were both one day, while the two sessions for BDS were one and seven days, respectively. The top panel of Figure 5 depicts the number of common-view satellites. Note that since we adopted the precise ephemeris to calculate the positions of satellites, the satellites without an available precise ephemeris were not counted, such as GPS satellite PRN 11. Furthermore, we note that the receivers could only record the observations of BDS satellites of PRN smaller than 30, while the full constellation of BDS consists of 44 satellites. This may have been due to the receivers not yet being updated to be capable of receiving all BDS satellites, as the BDS had not achieved a full constellation until the end of 2020. The bottom panel of Figure 5 shows the number of triple-differenced PCC measurements we constructed. As the blue shadows indicate, in the two time periods at the first and third days, the number of PCC measurements was low due to the small number of common-view satellites. However, there were also cases where the number of constructed PCC measurements was low during the period when the number of common-view satellites did not decrease. For example, on the eighth day, the number of constructed PCC measurements for BDS never exceeded six. This could be due to the cycle slip; we will come back to this later. Figure 4: Skyplot of PRN 29 of BDS in seven consecutive days (1–7 May 2022) at Curtin. In addition to the number of PCC measurements, the coverage of the satellites that are involved in constructing the PCC measurements are also important to the phase pattern fitting. To illustrate the distribution of these satellites, we provide the skyplots of GPS and BDS satellites in two and eight consecutive days, respectively, in Figure 6. Note that we artificially added 180\({}^{\circ}\) to the azimuth of satellites on the first day, filling the south hole. The distribution of GPS satellites was denser in the high-elevation region, compared with the north and south regions. We can also see that the distribution of BDS satellites was denser, as the data collection lasted longer. Figure 5: Number of common-view satellites (**top**) and constructed PCC measurements (**bottom**). The GPS data were collected for two days, and the BDS data were collected for eight days. The blue shadows denote the time periods where the number of common-view satellites was relatively low. Figure 6: Skyplot of (**a**) the GPS and (**b**) the BDS satellites that were used to construct the PCC measurements. These data were collected for two and eight days, respectively. Specifically, since the second session of data collection for BDS lasted for seven days, the north region in Figure 5(b) was as dense as the high-elevation region. Remark that this benefited from the fact that the ground trace repeat period of BDS MEO satellites was seven mean sidereal days. From Figure 7, we can also see that the satellite distribution of BDS kept changing during seven consecutive days. Consequently, although there were fewer observations available for constructing PCC measurements on the third (Figure 6(b)) and eighth days (Figure 6(g)), the overall satellite coverage was still good. Therefore, if sufficient time is available, it is recommended to collect the BDS data for up to 14 days, i.e., two sessions lasting for seven days each.