[time-nuts] Checking accuracy of Rubidium standards

Bruce Griffiths bruce.griffiths at xtra.co.nz
Mon Nov 10 09:29:01 UTC 2008


Bruce Griffiths wrote:
> Bill Hawkins wrote:
>   
>> -----Original Message-----
>> From: Bruce Griffiths
>> Sent: Sunday, November 09, 2008 10:00 PM
>>
>> -------%<--------
>> Thus
>> VAR(1) = (VAR(1,2) + VAR(1,3) - VAR(2,3))/2
>> VAR(2) = (VAR(1,2) + VAR(2,3) - VAR(1,3))/2
>> VAR(3) = (VAR(1,3) + VAR(1,3) - VAR(1,2))/2
>>
>> and
>> -------%<--------
>> Thus
>> ADEV(1) = (ADEV(1,2) + ADEV(1,3) - ADEV(2,3))/2
>> ADEV(2) = (ADEV(1,2) + ADEV(2,3) - ADEV(1,3))/2
>> ADEV(3) = (ADEV(1,3) + ADEV(1,3) - ADEV(1,2))/2
>>
>>
>> Bruce,
>>
>> Does the third equation really use ADEV(1,3) twice?
>> It doesn't have the same symmetry as the first and second
>> where each index shows up twice.
>>
>> Bill Hawkins
>>
>>
>>   
>>     
> Bill
>
> No it shouldn't, I obviously missed this when editing.
>
> they should be:
>
> VAR(3) = (VAR(1,3) + VAR(2,3) - VAR(1,2))/2
>
>
> ADEV(3) = (ADEV(1,3) + ADEV(2,3) - ADEV(1,2))/2
>
>
> Bruce
>
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>
>   
Oops, the last 3 equations should actually have been:

AVAR(1) = (AVAR(1,2) + AVAR(1,3) - AVAR(2,3))/2
AVAR(2) = (AVAR(1,2) + AVAR(2,3) - AVAR(1,3))/2
AVAR(3) = (AVAR(1,3) + AVAR(2,3) - AVAR(1,2))/2

That is the Allan variances, not the Allan Deviations.

Bruce



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