Blog Editor’s Note: A good case study below from Orolia. Of particular note is the comment that:
“Though the timing system used time servers that had internal atomic clocks and could operate through a temporary loss of the GNSS signals, this datacenter was critical to network operations. Thus, any signal loss became an issue.”
The folks at Orolia couldn’t, of course, identify the company impacted. They did say it was a MAJOR company and a MAJOR data center.
Golly, it seems time is important…
Using a Passive Anti-Jam Antenna to Combat GNSS Interference
Background
A customer with a major datacenter facility was experiencing issues with its GNSS basedtiming systems. For unknown reasons, GNSS reception was being intermittently lost. The timing system was architected and installed correctly using redundant time servers and components to ensure high availability and uptime. Testing was performed to ensure the fidelity of the system and components and the results indicated that everything was
functioning properly. However, the issues persisted and the GNSS signal was lost almost daily. Though the timing system used time servers that had internal atomic clocks and could operate through a temporary loss of the GNSS signals, this datacenter was critical to network operations. Thus, any signal loss became an issue.
Challenge
The GNSS signal losses were intermittent, and every time the signal was lost, the timing systems would go into holdover and generate alarms. This was more than a nuisance because they couldn’t be ignored; it was critical infrastructure. Even using sophisticated RF detection equipment yielded no results, because no interference or other issues were found when using detection equipment. Timing equipment changeout yielded no
improvements either. In addition, an audit of the installation confirmed that everything was properly installed. However, this loss of signal and associated alarms was taxing the network operators, consuming valuable management time and lowering their confidence in the robustness of the time synchronization system. Ultimately, we suspected that there was interference coming from an outside source.
Image: Glen Wallace, Inverness, Scotland – Inverness Farmers fleet, Wikimedia Commons
