[time-nuts] Testing the TAC, and a question about ADEV

Magnus Danielson magnus at rubidium.dyndns.org
Fri Dec 28 20:43:10 UTC 2012

On 28/12/12 20:33, Fabio Eboli wrote:
> Bruce, Bob, now I have more questions
> than before :)
> First and most important:
> Where can I find references about the
> statistical method you mentioned?
> I tried to search online but didnt't find
> any info.

The bucket statistic method is very simple.
You divide a scale into a suitable set of ranges, equally wide. The you 
count how many "hits" you get within each of those ranges or "buckets".

As your oscillators drift in phase relative to each other, you could 
divide that into say 1024 "buckets". In this case, you would choose the 
scale to stretch over the range of ADC values. Another way would be to 
stretch them over the saw-tooth ramp.

> What do you think about the simple setup
> I mentioned before (the 2 Rb osc)?
> If I set accurately the frequency difference
> (easy with a scope and a timer) I will know
> the cycle-by-cycle pulse increment
> (or reduction).

Yes. If you have a 1 s rate of measurement, dial in 1E-11 in frequency 
error, the advancement will be 10 ps (1E-11 s). The increment will be 
y*T where y is the relative frequency error and T is the interval.


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