[time-nuts] Counters for ADEV measurements

Tom Van Baak tvb at LeapSecond.com
Tue Oct 2 10:03:09 EDT 2012

> I'm also interested in this.  I've got one of these and a 53131A and
> am still learning the ins and outs of ADEV measurements with timelab.
> I was not aware of the 5/10MHz shortcomings of the 53131A that were
> discussed this weekend..
> Brent

To be fair, HP/Agilent did not hide this fact, but I agree it is buried rather deep in the 53131A/53132A manual. The new series (e.g., 53230A) has a similar issue. There's a wonderful paper by Robert Leiby about this design artifact:

"... Frequency Error near the Reference Frequency Harmonics"

This is no reason not to use a frequency counter in the lab. It simply explains why this class of counter works amazingly well at arbitrary frequencies and not quite as well right around magic numbers like 5 or 10 MHz.


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