Hi Paul,
Right, the averaging time, tau, is critical when quoting ADEV
numbers. In fact, the key feature of any ADEV plot is seeing
how stability changes as a function of tau. But Mark mentioned
"at 100 seconds" so that allowed me to compare his single
ADEV number against the tau 100 second column of a full
log-log plot.
Your data looks odd to me. Sample rate, or bandwidth, can
have a noticeable effect for short tau but I would expect that
by the time you're all the way out to tau 100 s that the points
would be about the same. Instead in your case they differ by
an order of magnitude.
Can you zip up the raw 5370 data for each run and email it
to me? That will help me spot the problem.
Thanks,
/tvb
----- Original Message -----
From: "Paul A. Cianciolo" <[email protected]>
To: "'Tom Van Baak'" <[email protected]>; "'Discussion of precise time and frequency
measurement'" <[email protected]>
Sent: Tuesday, August 30, 2011 8:24 AM
Subject: RE: [time-nuts] Question for any HP105 owners
Tom,
Is there an assumption that is normally made when referring to ADEV.
For example I looked at your image and see that you the chart begins at .1
seconds, so I am assuming that the sample rate was .1 sec to acquire these
numbers.
But Mark does not specify a sample time in his ADEV number.
Right now after I am testing a Rakon double oven oscillator and I see the
following.
Using a HP5370, z3801 reference for both the LO and the ref input on HP
Using .1 sec sample rate:
4.18 x 10 -11 @ 1sec
7.04 x 10 -12 @ 10 sec
1.11 x 10 -11 @ 100 sec.
Using a 1 second sample rate
3.85 x 10 -11 @ 1sec
4.01 x 10 -12 @ 10 sec.
9.60 x 10 -13 @ 100 sec.
This oscillator has been running now for barely 20 hours. The z3801a has
been running for about a year
Am I doing something wrong?
Thank you
Paul A. Cianciolo
W1VLF
http://www.rescueelectronics.com/
Our business computer network is powered exclusively by solar and wind
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Converting Photons to Electrons for over 20 years
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