White Rabbit – sub-nanosecond synchronization for large distributed systems
33 points by michaelsbradley 2 days ago | 7 comments
roughly 17 minutes ago
Haven't dug in on the technicals, but this is coming out of CERN, it looks like - and in that light, the links to "We're hiring" on that page almost feel like a flex...
replyskulk 2 hours ago
Haven't looked into this in depth but sub-nanosecond sync for systems up to 10km apart is interesting since 10km is about 33 light microseconds. There is some trickery going on.
replyelromulous 2 hours ago
It's totally possible to achieve synchronization better than light transmission time. For the purposes of synchronization, the speed of light delay, and any other delay are indistinguishable, and need not be distinguished.
replyooterness 45 minutes ago
Two-way time transfer measures the round-trip propagation time. As a result, it's not directly relevant to the accuracy.
replyUltraSane 2 hours ago
Yes, it uses phased locked loops and measures phase difference between the master clock and the local clock.
replycolechristensen 58 minutes ago
The gravity well time dilation is about 3.5 nanoseconds per meter per year near the surface of the earth. (time changes rate with altitude in a gravity well)
replySub-nanosecond synchronization is getting into the relativity is measurable realm.