[time-nuts] Allan deviation plots etc

[WarrenS]

>From what I have seen, Allan data has a major limitation for finding long term aging.
When you want to know what the aging will be over the next 10 years, 
Allan needs to have 30 or 40 years of data. Not the most practical way.

I have found for long term aging, taking data at around once per month generally does a good job, IF the osc is a "good osc"

Not sure if the attached under 60k plot will be seen.
It is plot of actual data for 3 of my Osc over a 5 to 9 year time span. (Ref was GPS)
The 10MHz SC10 shows a very consistent -8.3e-11 per day aging rate, after a two year 'warm up.'
The Dana 1992 high stability option shows a less consistent   +2e-10 per day rate, 
and the 5MHz, a small OXCO, has a Zero aging rate averaged over the last 6 years, and shows it can be pretty misleading to talk about just aging rate per year if the stability is not there.

warren

*******************
----- Original Message ----- 
From: "John Green" <wpxs472 at gmail.com>
To: <time-nuts at febo.com>
Sent: Tuesday, August 04, 2009 6:38 AM
Subject: Re: [time-nuts] Allan deviation plots etc


> 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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