[ntp:questions] project ntp.br - discrepancy from UTC

Unruh unruh-spam at physics.ubc.ca
Tue Jan 1 00:48:30 UTC 2008


david at ex.djwhome.demon.co.uk.invalid (David Woolley) writes:


>I seem to remember that typical NTP servers can lock to this to
>microsecond accuracies, although typical network delays will degrade
>this to around 1 ms.

Certainly my system, using a GPS18LVM gets a jitter or around 1usec,
much of which I suspect is the interrupt handling in the Linux operating
system. Other clocks which get time from that source using ntp seem to have
an offset of theorder of 50usec ( although this can depend crucially on the
load on the machines, network, etc). You can see some of this at
www.theory.physics.ubc.ca/chrony/chrony.html Note that all those machines
are in the same building as the ntp GPS server.





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