4 ms·
All these use at least GPS for timing
by misnome 10mo ago
All these use at least GPS for timing
- adastra22 10mo agoNo, they don’t. GPS is orders of magnitude less reliable than the most up to date metric time synchronization over fixed topology fiber links.
- misnome 10mo agoI wonder why we bothered building GPS signal waveguides into the bottom of a mine then. Clearly we should have consulted the experts of hacker news first. Losing NTP for a day is going to affect fuck-all.
- AlotOfReading 10mo agoI'm not even sure why you're trying to argue this. It's well established that Time over Fiber is 1-2 orders of magnitude more accurate and precise than GNSS time. Fiber time is also immune to many of the numerous sources of interference GNSS systems encounter, which anyone who's done serious timekeeping will be well acquainted with.
- misnome 10mo agoTrying to argue that neutrino experiments use GPS time, because they do? I’m sure synchronising all the worlds detectors over direct fiber links would… work, but, they aren’t. Unless you are trying to argue internal synchronisation in which case, obviously, but that has absolutely zero to do with losing NTP for a day, the topic of conversation.
- AlotOfReading 10mo agoThe deployments are still obviously limited, but this is something you can straight up buy if you're near a NIST facility [0]. I believe the longest existing link is NJ<->Chicago, which is used for HFT between the exchanges. [0] https://shop.nist.gov/ccrz__ProductDetails?sku=78200C https://shop.nist.gov/ccrz__ProductDetails?sku=78200C
- CamperBob2 10mo agoI doubt that very much. GPS time integrity is a big deal in many very important applications -- not the least of which is GPS itself -- and is treated as such. Yes, an individual fiber distribution system can be much more accurate than GNSS time, but availability is what actually matters. Five nines at USNO would get somebody fired.