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The United Kingdom’s primary steward of official time turned to Symmetricom when it needed to deploy a new methodology for providing time.
Overview
National Physical Laboratory (NPL), the United Kingdom’s national standards organization, maintains the nation’s standards for most physical measurements including time, length, mass, density and force. NPL is an internationally respected and independent center of excellence in research, development and knowledge transfer. The organization focuses on measurement and materials science, and for more than a century has operated at the forefront of science. Its measurement research and innovation are respected around the world and play a key role in supporting the competitiveness of UK companies.
Challenge:
NPL maintains time for the United Kingdom via a Symmetricom hydrogen maser clock and has traditionally distributed the time to the general public and businesses via radio signals as well as dial-in phone connections. Recently the organization began receiving many requests from end-users to provide time over the Internet.
NPL already had the ability to do this via four Symmetricom time servers it previously had in place for distributing time across its internal network. The organization decided to devise an architecture by which it would convert two of the Symmetricom time servers so that the general public could access them.
But before going public with the new service, NPL wanted to deploy a management system for which it could guarantee 24x7 access and 100-percent accuracy.
“We wanted to build an extra level of redundancy into the system,” explained Peter Whibberley, Senior Research Scientist for NPL. “Our internal clocks and the Symmetricom time servers are as reliable as any time devices in the world, but given the fact that businesses rely on us for providing time, we needed an absolute guarantee of accurate time.”
Thus NPL sought a solution that would inform them immediately if any problems occurred in the system. This would allow the organization to quickly switch time distribution over to another system and ensure customers would always retrieve accurate time.
Solution:
Having successfully utilized the hydrogen maser clock as well as four Symmetricom time servers (two TymServe 2100s and two NTS-200s), NPL had already become familiar with the reliability of Symmetricom products. Hence, Whibberley choose Domain Time II software from Symmetricom to monitor the time servers.
“We also researched other products just to ensure we would find the best possible solution and guarantee accurate time for our customers,” Whibberley said. “We could not find an alternative that even came close to Domain Time II.”
In deploying the new system, NPL configured the time service to originate from its hydrogen maser clock, traceable back to Coordinated Universal Time (UTC) and verified by a cesium clock. The two TS2100s synchronize to the extremely precise one pulse per second (1PPS) derived from the output of the maser with time of day for the 1PPS inserted via RS232 into the TS2100. The result is the TS2100’s become extremely precise network time servers. The two NTS-200’s then peer to the TS2100’s for accurate time and are available to serve time to the public via the Internet. If a breakdown occurs along one of the systems, NPL can re-route customers to the other system.
“This configuration gives us total control over the time we distribute,” Whibberley said. “We have two working systems, and we don’t have to rely on any outside sources such as the GPS (global positioning system).”
Results:
Domain Time II gives NPL a verifiable audit trail of the performance of the Symmetricom time servers, and the software automatically provides clear, indisputable records to easily resolve any time issues that arise. The records collected include complete information that allows NPL to determine precisely when each time server was last synchronized as well as its variance from the reference time source.
Whibberley found Domain Time II easy to install and use. “We did not require any help from Symmetricom,” Whibberley said. “The user interface of Domain Time II displays information efficiently so we can tell immediately how well the time distribution systems are performing.”
“Domain Time II essentially serves as an assurance policy for us,” Whibberley said. “We’re assured that whenever someone requests the time from one of our time servers, we will provide the correct time. Given the nature of what we do, our international reputation is at stake every time someone requests time from us, it’s critical that we never distribute inaccurate time.”
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