Datacenter GNSS Time Best Practices
Eight things worth doing, from the closing slide of a talk on getting the last nanoseconds to UTC. Most cost nothing but attention, and most of the error they remove is invisible until somebody checks.
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Topics In Timekeeping
What makes an accurate GNSS timing receiver?
Six traits, in the order they start to matter. The last one separates a box that wants to be your master clock from a box that knows you already have a better one.
Choosing a GNSS timescale for syncing datacenter clocks
You are not choosing a receiver so much as choosing whose timescale you end up on. There are three ways to do it, they differ by a factor of a hundred in cost, and most datacenters should take the cheapest.
How does GNSS holdover work?
When GNSS goes away your clock coasts on the frequency it was last told. How far it drifts is decided by your room more than your oscillator — which is why a holdover measurement and a holdover specification are different objects, and only one of them is a promise.
Questions to ask a clock vendor
Nine questions whose answers tell you whether a vendor understands their own product — no test equipment required.