[time-nuts] Fw: Rb Oscillator - rather fundamental question
Magnus Danielson
magnus at rubidium.dyndns.org
Wed Feb 24 07:49:14 UTC 2010
Rick Karlquist wrote:
> EWKehren at aol.com wrote:
>> The HP 5062C is not a "Primary Standard", and that is why it is called a
>> "Reference" because it uses a different transition of Cesium 133 with the
>> frequency of 9192.631,774,3 MHz which does not meet the definition of a
>> second
>> and resulted in a relative short product life even though modified to run
>> with a FTS tube and "Standard Frequency" makes it a grate Frequency
>> Standard.
>> Bert Kehren
>
> I never knew that. I stand corrected on the 5062C.
Ehm, no. This is just 4,3 Hz higher than the 0 C-field transition. It's
not a different transition, it is the C-field shifted (0, 0) transition.
I know of no Caesium clock that uses 0 C-field applied. The C-field
helps to spread out the 7 Rabi constellations such that the Ramsey
features can be investigated for the (0,0) transition can be
investigated correctly. This is a key to properly test the frequency.
The C-field shift is compensated for as it is fairly accuratly
predicted. The C-field is servoed by looking at the neighboring
tranistions Rabi constellations which depends stronger on the C-field.
This is what a "digital" Caesium does and is what is needed to become
primary standard as it removes aging in the C-field. The systematic
error that remains can be handled at design and trimmed in product
development.
The 5062C is not different in this respect.
So Rick, I don't find that you stand corrected.
Cheers,
Magnus
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