[time-nuts] Disciplining Rubidium
bruce.griffiths at xtra.co.nz
Thu Apr 24 08:30:14 EDT 2008
John Ackermann N8UR wrote:
> John Miles wrote:
>> Phase noise generally gets better with the higher-frequency OCXOs, though.
>> I think the best of all possible worlds would be a 5-MHz OCXO like the one
>> you describe, being used to discipline a 10 MHz or higher-frequency part.
>> -- john, KE5FX
> I'm not sure about that -- at least, the Wenzel ULNs show better noise
> at small offsets for the 5 MHz than the 10 MHz versions (though the
> floor is the same).
Surely the fact that the product of quartz resonator Q and its resonant
frequency is approximately constant has something to do with this via
the Leeson effect?
Higher frequency crystals tend to have lower Q and hence lower close in
phase noise at a given offset this being somewhat exacerbated by the
fact that the higher frequency crystal tends to have a wider resonator
The way to improve this is to find a substance with a larger Q at a
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