On Tue, 4 Oct 2016 15:41:58 +1100 Larry Hower <ho...@hower.net> wrote:
> Ultimately we want sub-millisecond accuracy. If you want to go that way, you will have to leave windows as this operating system does not offer the facilities to get down to such a low level....Unless you calibrate the whole path by injecting a time pulse into the signal path like Jim Lux and TvB suggested With linux you can get systems synchronized to better than 1ms by using a PTP server in the local network or by directly using PPS. This should get you in the order of better than 100µs probaly 20-30µs. BTW: A word of advice against using NTP servers over the internet for accurate time distribution. I recently set-up two NTP servers to be used as stratum 2 servers (server A and B). Both synchronize to the same stratum 1 server (server S), but are at different ISPs and thus use different paths. NTP on both A and B reports the following values (current snapshot, values are representative): Link delay offset jitter A-S 4.205 0.020 0.081 B-S 2.112 0.039 0.079 A-B 0.606 -0.877 3.192 (as reported by A) I.e. even though A and B use the same server S as reference, the time difference between both servers is 800-900µs. I am not sure where this path asymmetry comes from, but my guess would be on the connectivity of A (there are two groups of stratum 2 it syncs to and one of them shows the same ~900µs offset). I also do not know why the jitter between A and B is so large even though the delay is pretty low (seems to be a weirdness at a router inbetween). Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.