Figures of merit for time servers

[Gary E. Miller]

Yo Clark!

On Mon, 23 May 2016 21:47:39 -0400
"Clark B. Wierda" <cbwierda at gmail.com> wrote:

> What are the figures of merit that we should be tracking when
> monitoring the quality of servers using NTP for exchange?

I think you have the basics: offset, dispersion, jitter, wander.  Plus the
50%, 95% and 90% bounds of those.

If we get a handle on that we can look at Allan Deviation (ADEV), but
we are way far away from that now.

> Based on Gary's message (I hope it was Gary), we should use the same
> terms to reference the same "thing".  We should be precise in that
> usage and avoid the softer terms.

The NTP doc pretty much defines our topic words.

http://support.ntp.org/bin/view/Support/NTPRelatedDefinitions

But it does get a bit sloppy on some terms like "accuracy".

> Once I have some data, I can figure out a good way to display it and
> iterate from there.

In a related space (time-nuts), they use a mostly widows program
called "Lady Heather".  It has some nice ideas.

http://www.ke5fx.com/heather/readme.htm

See attached for a cool screen shot of its output.

One cool thing on it is the Allan Deviation (ADEV) data.

Sadly it is specific to the Trimble style of cell tower reference
clocks.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588
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