Research on Time Comparison Based on Galileo PPP

Time comparison based on global navigation satellite system (GNSS) is one of the main techniques in Coordinated Universal Time (UTC) calculation. At present, there is a goal to promote the Galileo system to join the UTC calculation to provide high-precision services for users all over the world. In this paper, the Precision Point Positioning (PPP) time comparison based on Galileo is studied. The data used in this paper include the original data of pseudo-range and carrier phase from National Time Service Center of Chinese Academy of Sciences (NTSC) and Royal Observatory of Belgium (ROB), and the data of precision orbit and clock offset released by International GNSS Service (IGS) which includes the German Research Center for Geoscience (GFZ), Centre for Orbit Determination in Europe (CODE) and Shanghai Astronomical Observatory (SHAO). The results show that the pseudo-range multipath noise of E1 and E5a are all less than ±1 m. When the Galileo PPP is applied to the short baseline common clock time comparison, the time difference by using the precision products of three analysis centers are less than ±0.5 ns, and the standard deviation of the time difference are less than 0.2 ns. For long baseline of Asia Europe time comparison, based on the precision products of three IGS analysis centers, the time comparison between UTC(NTSC) and UTC(TP) by using Galileo PPP have the same trend as the GPS PPP, which is released by International Bureau of Weights and Measures (BIPM), the stability of Galileo PPP is the same with GPS PPP, and it can reach to E-15/ day. As a result, with the performance improvement of Galileo system, the high-precision time comparison based on Galileo will provide better services for users, and the experiment results indicate that the Galileo can also be used as one of the formal methods by BIPM for precision time comparison in the future.