Ethernet Time Transfer through a U.S. Commercial Optical Telecommunications Network, Part 2

Marc Weiss, and Jian Yao, Lee Cosart, James Hanssen

Abstract:	There is a need to back up critical timing infrastructure at the national level. This paper provides an update on a joint project employing commercial equipment to send national timing signals through a telecommunication network. This experiment connects the UTC(NIST) time scale located in Boulder, Colorado with the UTC(USNO) Alternate Master Clock time scale located at Schriever AFB in Colorado via a telecommunication provider's optical network. Timing signals using the Precision Time Protocol (PTP) were sent in the usual two-way fashion, but each one-way delay was measured, because we had UTC time scales at both ends of the network that were within 10 ns of each other. This part of the experiment is now nearly complete. The experiment was started in April 2014 and extensions of the project will run through the end of 2016. It appears that there is at least one commercial transport mechanism that could serve to back up GPS for time transfer at the 100 ns level. We found that the asymmetry of the PTP time transfer resulted in 10’s of microseconds of time transfer error, but that the stability through the entire connection was less than 100 ns, as long as the connection remained complete. This implies that if the time delays of the network could be calibrated, it could maintain under 100 ns accuracy as long as it did not go down. We have established the likely causes of the bias, as well as run simulations of various configurations in a laboratory. Thus, we have some certainty that similar results will apply if this technique were used as a service across the country. While many researchers have shown that fiber can transfer time and frequency with high accuracy, this experiment addresses the practicality of using the US telecom infrastructure for timing.
Published in:	Proceedings of the 47th Annual Precise Time and Time Interval Systems and Applications Meeting January 25 - 28, 2016 Hyatt Regency Monterey Monterey, California
Pages:	107 - 115
Cite this article:	Weiss, Marc, Yao, Jian, Cosart, Lee, Hanssen, James, "Ethernet Time Transfer through a U.S. Commercial Optical Telecommunications Network, Part 2," Proceedings of the 47th Annual Precise Time and Time Interval Systems and Applications Meeting, Monterey, California, January 2016, pp. 107-115. https://doi.org/10.33012/2016.13153
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In