[time-nuts] Allan Deviation recipe?

Gary E. Miller gem at rellim.com
Mon Jul 18 22:01:58 EDT 2016


Yo Tom!

On Mon, 18 Jul 2016 18:42:39 -0700
"Tom Van Baak" <tvb at LeapSecond.com> wrote:

> Lots of ways to do it. There are GUI tools; command line tools, in C
> or Python or Matlab.

Got some C or Python?

> But to start with I highly recommend using John's TimeLab:
> http://www.ke5fx.com/timelab/readme.htm

I don't do Windows...  And I want this to auto-generate graphs for web
pages on RasPi's.  Lot's of RasPi's.  :-)

> Here's a sample 1PPS phase (time interval error) data file (from a hp
> 53132A): http://leapsecond.com/pages/MG1613S/log167.txt

Yeah, that looks sorta like what I have.

> Or here's the same file in a more standard format:
> http://leapsecond.com/pages/MG1613S/log167.dat

Just the facts there, i can do that.

> http://leapsecond.com/pages/MG1613S/log167-adev.gif

That's what I think I am looking for.

A bit of background.  Ntpd generates a number they call the Allan
Deviation, but the description looks like the Allan Variation, they
describe is as the minima in the Allan Deviation plot, when it has a U
shape.

They then use that number to set the PLL optimally.

Something looks fishy to me, so I want to visualize it, and help the
rest of the NTPsec team see it as well.

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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