[time-nuts] AVAR calculation

Tom Van Baak tvb at LeapSecond.com
Tue Jan 12 21:06:40 UTC 2010


> Second thought, look at the tau=1 to 10 s and you see that it first 
> rises before the usual slope. This is the effect of averaging in the 
> counter. I would suspect that a HP53132A is being used.

Magnus,

You're correct about averaging effects; for example, see:
http://www.leapsecond.com/pages/adev-avg/

But, I think in this case it's not the measurement system
that's causing it because I saw the same PRS10 hump:

http://www.leapsecond.com/museum/prs10/1sigma2.gif
http://www.leapsecond.com/museum/prs10/log16084v.gif
http://www.leapsecond.com/museum/prs10/

What we see then would appear to be a feature of the PRS10
itself and not  the measurement system. Since the PRS10 is
based on a quality SC-cut OCXO, this might be an artifact of
their blending the OCXO and Rb cell; i.e., it looks just like a
GPSDO PLL hump, only moved two decades to the left.

/tvb




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