[time-nuts] Counter averaging errors near clock harmonics

Magnus Danielson magnus at rubidium.dyndns.org
Sun Apr 12 03:35:43 EDT 2015


On 04/10/2015 09:27 PM, Charles Steinmetz wrote:
> The subject of errors in averaging counters at input frequencies near
> the clock frequency and its subharmonics and harmonics comes up on the
> list from time to time.  There is a nice discussion of the phenomenon,
> and how it was addressed in the design of the HP 5345A counter, in the
> June, 1974 issue of the Hewlett-Packard Journal:
> David C. Chu, "Time Interval Averaging: Theory, Problems, and
> Solutions," HP Journal v25 n10, June 1974
> <www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1974-06.pdf>

Good point. This technique is also used in the HP5328A, but only for TI 
averaging, not for frequency measurement.


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