[time-nuts] GPSDO TC & Damping
Magnus Danielson
magnus at rubidium.dyndns.org
Sat Jan 10 09:49:00 UTC 2009
Dick,
> Sorry, Magnus, I didn't mean to put words in your mouth.
No worries, I just did not want it to be raised to "truth".
> I was remembering last Fall, when you suggested that people look at your
> ADEV plot and to be mindful of the of the bounding slopes of the
> curves. If I've mis-remembered the emphasis or the facts, I do
> apologize. I thought your argument then, as I remember it, was strong
> and valuable. Seems like it gave a good range of possible values to
> use for Tau in the measurements.
Do not recall the particular discussion. A ref into the archives or date
would be apprechiated.
> I probably won't go far beyond the capabilities of the TBolt, such as
> implementing a PID controller with dynamic control of variables using
> a microcontroller and LPGAys and writing my own software, but I love
> it when you talk that way.
Sounds dangerous. :)
I have been looking further into the variance, ADEV, MDEV and TDEV with
respect to the effect of various dampings. It is becomming clear to me
that the gain effect which can be attributed to damping will ripple over
to all those measures. I have not had the time to convert this to a
complete analysis, but I think I can do that.
However, to give a partial answer to Bruce, I would like to point to a
passage in Gardiner where the optimum damping for minimum flicker noise
is being found, and that is for 1.14 rather than 0.5 which would be
minimum noise bandwidth. Gardiner does not go into ADEV and friends, but
does provide the refernces and gives an indication of convergance
problems for flicker noise on variance, also indicating that this is a
problem for further analysis. Using ADEV and friends in replacement
analysis could be made analogously for other noise types and as it
happends also work in cooperation with investigating the effect on
various noisetypes.
Regardless, it is an interesting little problem and I get to exercise
the little grey and refresh my always failing abilities in integration.
Cheers,
Magnus
More information about the Time-nuts_lists.febo.com
mailing list