## 5 Performance Assessment of BDS-3 Satellite Clocks
### Results
The average accuracy of BDS-3 with PHM is slightly worse than that of the GPS and Galileo satellites, while the accuracy of BDS-3 with RAFS is basically comparable to the BDS-2 IGSO and MEO satellites. Figure 11: Averaged frequency stability with the averaging time of 300 s, 10,000 s, and 86,400 s for BDS-3 RAFS and PHM satellites. Figure 10: Averaged frequency accuracy and frequency drift rate during the whole assessment period for BDS-3 RAFS and PHM satellites. Note the y-axis of frequency drift rate for BDS-3 PHM is on the right side. In terms of the daily frequency drift rate, the result of BDS-3 with RAFS is 0.1-\(2\times 10^{-13}\) with an average value of \(1.48\times 10^{-13}\). Only C19 is in the order of \(1\times 10\)-14, while other RAFS satellites are about 1-\(2\times 10^{-13}\) with a small variation. The range of BDS-3 with PHM is \(3\times 10^{-16}\)-\(4\times 10^{-14}\) with an average value of \(1.05\times 10^{-14}\). C34 and C35 with PHM are relatively bad with the values of \(3.01\times 10^{-14}\) and \(4.49\times 10^{-14}\), respectively, which are worse by at least one order of magnitude than the other PHM satellites. The drift rate of GPS satellites is about 0.7-\(4\times 10^{-14}\) with an average value of \(2.22\times 10^{-14}\), and the difference among GPS satellites is small. The drift rate of Galileo satellites is about 0.2-\(3\times 10^{-15}\) with an average value of \(1.25\times 10^{-15}\), which presents the best result and is comparable to the result of [35]. The average drift rates of BDS-2 GEO, IGSO, and MEO satellites are \(6.86\times 10^{-14}\), \(6.27\times 10^{-14}\), and \(9.04\times 10^{-14}\), respectively, which are comparable to the results of [34]. The results of C03, C04, C06, C16, and C14 are in the order of \(1\times 10^{-13}\), which are relatively worse than the other satellites. The frequency drift rate of BDS-3 with RAFS is basically comparable to BDS-2 MEO satellites and worse than GPS IIF satellites, while that of BDS-3 with PHM, except C34 and C35, is slightly worse than Galileo PHM satellites. In terms of the stability with the averaging time of 300 s, the result of BDS-3 RAFS is about 0.8-\(1\times 10^{-13}\) with an average value of \(9.43\times 10^{-14}\), and similarly, the result of BDS-3 PHM is about 0.8-\(1\times 10^{-13}\) with an average value of \(9.07\times 10^{-14}\). The stability of GPS satellites is about 8-\(9\times 10^{-14}\) with an average value of \(8.91\times 10^{-14}\), and for Galileo satellites, it is 6-\(7\times 10^{-14}\) with an average value of \(7.08\times 10^{-14}\). The average result of BDS-3 PHM satellites is slightly worse than GPS and Galileo. The stability of BDS-2 GEO, IGSO, and MEO satellites is \(1.91\times 10^{-13}\), \(2.76\times 10^{-13}\), and \(2.02\times 10^{-13}\), respectively, showing BDS-3 RAFS is better than BDS-2 satellites. BDS-3 RAFS is slightly worse than GPS IIF RAFS satellites. In terms of the stability of the averaging time of 10,000 s, the range of BDS-3 RAFS satellites is 2-\(3\times 10^{-14}\) with an average value of \(2.49\times 10^{-14}\). Almost all satellites are smaller than \(3\times 10^{-14}\), which is better than that of GPS satellites with an average value of \(4.14\times 10^{-14}\) and variation range of 2-\(6\times 10^{-14}\). The stability of BDS-2 GEO, IGSO, and MEO satellites is \(5.90\times 10^{-14}\), \(5.45\times 10^{-14}\), and \(4.52\times 10^{-14}\), respectively, which is better than the results of [13] with the 10,000 s stability being about 8-\(11\times 10^{-14}\), 6-\(12\times 10^{-14}\), and 4-\(6\times 10^{-14}\), respectively. It can be seen that the result of BDS-3 RAFS is better than that of BDS-2 satellites. The 10,000 s stability of BDS-3 PHM is 1-\(2\times 10^{-14}\) with an average value of \(2.32\times 10^{-14}\), which is slightly worse than that of Galileo satellites with an average value of \(1.77\times 10^{-14}\) and variation range of 1-\(2\times 10^{-14}\).