White Rabbit Precision Time Protocol on Long-Distance Fiber Links

Abstract

The application of White Rabbit precision time protocol (WR-PTP) in long-distance optical fiber links has been investigated. WR-PTP is an implementation of PTP in synchronous Ethernet optical fiber networks, originally intended for synchronization of equipment within a range of 10 km. This paper discusses the results and limitations of two implementations of WR-PTP in the existing communication fiber networks. A 950-km WR-PTP link was realized using unidirectional paths in a fiber pair between Espoo and Kajaani, Finland. The time transfer on this link was compared (after initial calibration) against a clock comparison by GPS precise point positioning (PPP). The agreement between the two methods remained within [Formula: see text] over three months of measurements. Another WR-PTP implementation was realized between Delft and Amsterdam, the Netherlands, by cascading two links of 137 km each. In this case, the WR links were realized as bidirectional paths in single fibers. The measured time offset between the starting and end points of the link was within 5 ns with an uncertainty of 8 ns, mainly due to the estimated delay asymmetry caused by chromatic dispersion.

Time Synchronization Mechanism for Radio Interferometer Array

“…(Table 2). The proposed algorithm performed better then [13,16]. Therefore, accuracy may reduce in real hardware implementation [17,18].…”

Fibre-optic delivery of time and frequency to VLBI station

“…Many such links, at both experimental and operational levels, have been recently established (Lopez et al 2010(Lopez et al , 2012Droste et al 2013;Śliwczyński et al 2013;Calonico et al 2014;Dierikx et al 2016). There are, however, specific issues related to vulnerability of the fibres to environmental factors that should be addressed to ensure high stability of delivered synchronization signals.…”

“…The cancellation of the delay fluctuations may be performed directly in the optical or electrical domain (Ma et al 1994;Lopez et al 2010;Droste et al 2013;Śliwczyński et al 2013), or realized at the software (protocol) level (Dierikx et al 2016).…”

A Comprehensive Technological Survey on Dependable Self-Managing CPS: The Decade of Researches on Correctness and Dependability

“…As timing has never been treated as a basic premise ago [109], it needs to reconsider the role of timing to CPS. Researches already try to redesign the whole system from hardware platforms [110] to operating system [111], from programming models [112] to architectures [25], from time synchronization protocols [26] to communication standards [113][114][115].…”

“…Moreover there are also lots of explored technologies for building CPS, e.g. precision timed infrastructure [24], temporal isolation [25], precision time protocol [26], hierarchical scheduling, and various of modeling methods. Therefore, CPS has been applied in different areas: e.g.…”