[time-nuts] Allan deviation plots etc

John Green wpxs472 at gmail.com
Tue Aug 4 13:38:12 UTC 2009


Ulrich Bangert wrote:
my point has not been to judge who has to be interested in what. My point
has only been to use the right terms for it. Let me give an example: John
uses the term

> ...but I am more concerned with ... and stability over time

Well, stability over time is what exacly is displayed in a tau-sigma-diagram
of an oscillator. Since only a few words before he is saying that he is NOT
intersted into Allan Deviation plots, then he is perhaps interested into
something else?

Allan deviation plots are interesting and if I had the means to generate
them, I certainly would. Since I don't, I find it easier to interest myself
in ways to try to measure oscillator performance in  practical terms with
the equipment at hand. What I would really like is to be able to produce a
specification in the same form as the oscillator manufacturers. I am used to
data in that form and while the Allan deviation gives somewhat the same
data, I rarely see one that gives a clue to stability over a year or 10
years. Most of the ones I see seem more concerned with seconds to hours and
maybe weeks at most. Of course, my method won't give any clue as to how an
oscillator will perform over years either.
I hope this clears things up a bit.


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