White Rabbit Time Transfer on Medium and Long Fibre Hauls at INRIM

G. Fantino, G. Cerretto, R. Costa, D. Calonico

Abstract:	Time Transfer (TT) techniques are essential systems in time metrology, mainly for comparing remote UTC(k) time scales, disseminating time to users and granting for the interoperability among navigation satellite systems. Presently, TT techniques are mainly based on satellite systems, namely the GNSS (e.g. P3 and Precise Point Positioning) and the geostationary ones (e.g. TWSTFT), that allow the synchronization of time scales with an uncertainty of one nanosecond, in a continuous international effort to improve their accuracy, instability and latency. Recently, optical fiber based techniques showed excellent results for frequency transfer applications [1], and international on-going studies aim to investigate the possibility to exploit them for time transfer and dissemination. Among these techniques, the “White Rabbit” (WR), a system based on dedicated equipment using a combination of Synchronous Ethernet ITU-T standard (SyncE) and enhancements of the PTP protocol (IEEE 1588). This system allows for self-calibrated synchronization with sub-ns accuracy and instabilities at the level of tens of picosecond, nominally over short baselines (theoretically 10 km max). On this domain, MIKES, the Finnish national metrological institute, demonstrated a WR time dissemination over 900 km long fiber haul, reaching an uncertainty of about 2 ns, assessed through a GPS-PPP comparison over the same baseline [2]. In this work, we present the WR system implemented at INRIM for medium hauls fiber dissemination, its preliminary metrological characterization in terms of accuracy and instability, and a medium-long term project for disseminating the Italian standard time to remote users.
Published in:	Proceedings of the 46th Annual Precise Time and Time Interval Systems and Applications Meeting December 1 - 4, 2014 Seaport Boston Hotel Boston, Massachusetts
Pages:	45 - 51
Cite this article:	Fantino, G., Cerretto, G., Costa, R., Calonico, D., "White Rabbit Time Transfer on Medium and Long Fibre Hauls at INRIM," Proceedings of the 46th Annual Precise Time and Time Interval Systems and Applications Meeting, Boston, Massachusetts, December 2014, pp. 45-51.
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