A comparison of GPS common-view time transfer to all-in-view

Abstract

Abstract-All-in-view time transfer is being considered to replace common-view for computing the links of International Atomic Time (TAI). The components in all-in-view GPS time transfer that do not cancel as they do in the common-view technique are the satellite clock estimate and the ephemeris estimate. We show that these components average down as white phase noise with a typical level of 2 ns with 13 minute averaging,and under 100 ps at 1 d. Looking at closures including stations in Europe, North America and Japan, we see evidence for a white PM level below 0.5 ns with an averaging time of 1 d, a flicker floor of 100 ps after 3 d, and systematic effects at a level of up to 1 ns. We also show evidence that errors in ionospheric maps and multi-path interference can cause noise processes at least as dispersive as flicker phase noise at 300 ps from 1 d to past 10 d. We conclude that all-in-view GPS time transfer improves stability over common-view for links as long as 5000 km, and is equivalent for links as short as 2500 km. We also find that ionosphere-free time transfer data may provide a significant improvement for averaging past 1 d.

Combining GPS and GLONASS for time and frequency transfer

“…The drawback of the method is that the number of satellites in common visibility is smaller than the number of visible satellites for one given station, which reduces the number of data available for the analysis. It is now accepted that for time transfer based on the analysis of only GPS code measurements, the use of "all-in view" method is better than "common view" for baselines larger than 2500 km (Weiss et al, 2005). When using the combined analysis of code and carrier phases, this limit distance is reduced to about 2000 km but the use of intermediary stations reducing the baseline length allows us to retrieve the quality of the solutions obtained for short-baselines (Martìnez-Belda and Defraigne, 2010).…”

On the impact of Group Delay Variations on GNSS time and frequency transfer

“…The applied time transfer methodology equals the All -In -View technique, since all satellites visible above an elevation of 5 • are considered. The advantage of using All -In -View w.r.t Common -View techniques are discussed in detail in [20]. For every station, receiver clock solutions with four antennae are obtained, each set with 80640 epochs with a 15 s sampling rate.…”

Improving the Performance of Multi-GNSS Time and Frequency Transfer Using Robust Helmert Variance Component Estimation

“…Since the Global Positioning System (GPS) was first utilized for precise time transfer [ 1 ], it has increasingly been applied in time frequency dissemination. From initial common-view (CV) and all-in-view (AV) techniques [ 2 , 3 ], which use only pseudo-range measurements, to the development of carrier-phase (CP) techniques that combine carrier phase observation [ 4 ], the accuracy of GPS time transfer has improved significantly. While earlier studies employing CV and AV techniques have recently been re-evaluated, research on GLObal Navigation Satellite System (GLONASS) time transfer has also increasingly been undertaken in those years [ 5 , 6 ].…”