[time-nuts] Yb clock - stability estimation procedure?

Magnus Danielson magnus at rubidium.dyndns.org
Mon Aug 26 02:01:24 EDT 2013


On 08/25/2013 08:25 PM, Bob Camp wrote:
> Hi
>
> The most common approach is to *assume* that the two devices are not correlated. SInce it's a negative, you really can't prove it. What you can do is to disprove it by finding and documenting  a correlation. 
>
> ADEV it's self has a confidence level based on the number of samples taken. What is normally reported is the calculated number, not the number plus the uncertainty. The same carries over to the square root of 2. It's simply the best estimate of what's going on. As long as they say what the do / do what they say, it's not really a problem. 
>
> The next step is typically to build a couple more devices and start doing a simultaneous  N way comparison. That will let you play with math and better estimate the performance of each of your devices. The best case would be to compare devices made by different labs using different approaches. That usually lets you spot the correlation issues between devices.
Exactly. As you have three devices, measuring them pair-wise you get
three measures and three un-knowns, and you can untangle the stability
of each individual. If you have yet more, you can get some confidence
levels also as it becomes overdetermined.

Cheers,
Magnus


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