[ntp:questions] Slow convergence loopstats (but nice results)

Terje Mathisen terje.mathisen at tmsw.no
Wed Dec 11 20:04:07 UTC 2013

schmidt.rich at gmail.com wrote:
> I do the latter. To use PTP to timestamp one would have to modify NTP
> source outside of refclock_phc(), which we would not presume to do.
> However the PHC loopstats has a standard deviation of 0.58
> microseconds, so we are not far off in using standard NTP
> timestamping.


It is extremely sad that history have saddled us with extremely poor 
motherboard clock crystals, but now, more than 30 years after the 
original IBM PC, we're getting something which is a couple of orders of 
magnitude better, but as a pure side-effect of the need to time network 
packets. :-(

> Rich Schmidt
>> Do you use the PTP hw to also timestamp actual ntp packets, or just
>> the
>> onboard tcxo (or whatever the LAN card osc is) as a stable time
>> base?
>> Terje

- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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