Improving long-baseline rapid GPS time transfers by a modified common-view method

Abstract

We propose a new data analysis process that is referred to as the upsampled common-view (UCV) method, which evolved via the interpolation techniques of portable clock trips and digital signal processing. By interpolating the locally measured global positioning system (GPS) P3 code time offsets to obtain global visible common-view (CV)-like results, we increase the number of data points at each epoch; these points are not restricted to the epoch in which the observations occur. The time transfer results between two laboratories are obtained from a weighted average among all the visible GPS satellites. Daily files of GPS observation data were used in the study. We demonstrate the results of three long-baseline links among the Telecommunication Laboratories (TL) in Asia, the Physikalisch-Technische Bundesanstalt (PTB) in Europe and the United States Naval Observatory (USNO) in North America. The rapid UCV results provide time stability at the level of 100 ps at averaging times around 1 d, which is comparable to the P3 all-in-view (AV) results. Comparing the UCV results with precise point positioning (PPP), the root mean square (RMS) of the double differences for the TL-PTB, TL-USNO and USNO-PTB links are 0.29 ns, 0.38 ns and 0.34 ns, respectively, during a period of 40 d. The low RMS values show that the smooth UCV results are close to the PPP results.