Best practices question
paul at anastrophe.com
Wed Jun 26 20:14:36 UTC 2019
On 6/26/19 11:22, Paul Theodoropoulos wrote:
> wow, fascinating - I set my c-ntpsec PPS min/maxpoll to 2. The RMS
> time jitter rose a fairly significant amount, from hovering around
> 0.6µs to now 1.0µs -- while the RMS frequency jitter plummeted from
> hovering around 4ppb down to, well, barely discernably above 0ppb on
> the graph.
> eh, saying it just doesn't tell the story -
> Time jitter: https://i.imgur.com/jNlaAAj.png
> Frequency jitter: https://i.imgur.com/wAF2nu9.png
I think maybe I'm hitting a bug or I'm just not understanding (usually
the latter), as it doesn't seem possible:
jitter fluctuating between 400 parts per trillion and 800 ppt?? From a
Raspberry Pi running at 1.4Ghz?
That said, I switched to min/maxpoll 1 for PPS, and saw a corresponding
change - so Time jitter appears to be inversely correlated to Frequency
jitter - less frequency jitter, more time jitter, and vice-versa. This
is all fascinating.
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