[ntp:questions] Can NTP sync within 1ms
unruh at invalid.ca
Tue Apr 29 16:15:36 UTC 2014
On 2014-04-29, Rob <nomail at example.com> wrote:
> William Unruh <unruh at invalid.ca> wrote:
>> The problem is not the electronics, it is the response of the system to
>> the interrupt. That interrupt processing time is in the usec range.
> This does not really matter when it is constant.
> And my experience is that the jitter on the PPS refclock is usually
> 0, 1 or 2us when I check it.
That sounds like 100% variability. And the serial port level converter
time delay is much more constant.
Also look at the jitter when the system is heavily loaded with disk
input/output or network load.
> On a newer server that has just been configured for this task it is
> the same:
> remote refid st t when poll reach delay offset jitter
> oPPS(0) .PPS. 0 l 16 16 377 0.000 -0.001 0.001
> (the GPSDO is still synchronizing, things may be even better after that)
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