[time-nuts] Characterising frequency standards

Steve Rooke sar10538 at gmail.com
Thu Apr 9 12:00:13 UTC 2009


2009/4/9 Tom Van Baak <tvb at leapsecond.com>:
> The first argument to the adev1 program is the sampling interval t0.
> The program doesn't know how far apart the input file samples are
> taken so it is your job to specify this. The default is 1 second.
> If you have data taken one second apart then t0 = 1.
> If you have data taken two seconds apart then t0 = 2.
> If you have data taken 60 seconds apart then t0 = 60, etc.
> If, as in your case, you take raw one second data and remove
> every other sample (a perfectly valid thing to do), then t0 = 2.
> Make sense now? It's still "continuous data" in the sense that all
> measurements are a fixed interval apart. But in any ADEV
> calculation you have to specify the raw data interval.

I think the penny has dropped now, thanks. It's interesting that the
ADEV calculation still works even without continuous data as all the
reading I have done has led me to belive this was sacrosanct.

What I now believe is that it's possible to measure oscillator
performance with less than optimal test gear. This will enable me to
see the effects of any experiments I make in the future. If you can't
measure it, how can you know that what your doing is good or bad.

Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW
Omnium finis imminet

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