Session P4a: T&F Transfer Utilizing Existing and Emerging Communication Systems

White Rabbit based National infrastructure for Time and Frequency Distribution
Vladimir Smotlacha, CESNET Josef Vojtech, CESNET
Location: Seaview A/B
Date/Time: Thursday, Jan. 30, 9:20 a.m.

National research and education optical network serves primarily for Internet connectivity of participating 26 universities and 57 institutes joined in the Academy of Sciences. The network optical layer has been carefully tailored also for non-data photonic services, including time and frequency, e.g. to comparing of atomic clock time scales that we started more than 10 years ago. Our participating partners are joined in non-commercial activity CITAF; as a result of this cooperation and based on long term experience, we decided to provide access to accurate time and stable frequency also to other users. We have started to build wide infrastructure for accurate time and frequency transfer to majority of CESNET network nodes utilizing the White Rabbit technology.
The deployed infrastructure will consist of 20+ nodes including two sites in neighboring countries where is available a cross-border links: Vienna in Austria and Cieszyn (alternatively Wroclaw) in Poland.
Starting principles for the infrastructure:
- At least two independent atomic references compared each to other by other GNSS calibration receivers.
- Traceability to UTC(TP), the national approximation of UTC time scale.
- Use of reserved bandwidth in telecom optical fibre backbone fiber deployed with multivendor flex spectrum DWDM (Dense-Wavelength Division Multiplexing) between distant points of presence.
- Dedicated bidirectional amplifiers.
- Fully reciprocal path between main nodes to minimize uncertainties.
- Dedicated bidirectional fiber between point if presence and service client.
- Permanent monitoring to check performance and accuracy of distributed time.
- Utilization of advanced commercial resilient White Rabbit devices (multi source, redundant power supply, ...)
At the PTTI meeting, we will present detailed plans, tender/deployment status and up-to-date experience with our time and frequency infrastructure.