[time-nuts] Re. DIY atomic "resonator" 6GHz synthesizer from ADI

Bob kb8tq kb8tq at n1k.org
Tue Apr 11 22:13:25 EDT 2017


If you make the cells in the basement (or even in most factories) the ability to have a wide range
synthesizer will come in handy. The whole “6.834xxx GHz” thing is dependent on a number of variables. 
It is not at all uncommon to produce cells that come out 10’s or 100’s of KHz off of the “right number”.
Wide range synthesizer = higher yield. 


> On Apr 11, 2017, at 10:00 PM, Richard (Rick) Karlquist <richard at karlquist.com> wrote:
> You always want two frequency sources.  One generates a carrier
> frequency offset many MHz from 6.834 GHz and the other frequency
> source modulates the carrier with a sideband that is at the
> exact ~6.834 GHz frequency that finds the atomic line.  The
> sideband is in turn modulated with audio to find the exact
> center of the line.  This is now the easiest section to
> design.
> This architecture automatically gives you gobs of resolution.
> Of course you always have the C field for infinite resolution.
> The other thing it does is prevent RF leaks from exciting the
> atoms, since the strong LO is safely offset from 6.834.
> Rick N6RK
> On 4/11/2017 2:59 PM, paul swed wrote:
>> When I read about the frequency generation in the Rb or CS there are
>> normally many numbers associated with the actual frequency. Down to at
>> least the 1 Hz level. Many of these PLLs are intended for multi-KHz steps.
>> I speculate you might need 2 PLLs one thats very fine in I hz increments
>> that gets added to something like these PLLs that step in 200 KHz
>> increments.
>> Regards
>> Paul
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