[time-nuts] ensemble oscillators for better stability

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sun Dec 30 17:30:50 UTC 2012


Azelio Boriani wrote:
> and not having a -175dBc/Hz reference, how you can tell that your dual
> -150dBc/Hz performs like a -170dBc/Hz?
>    
You can't.
> Moreover: what is the physical principle that can explain this? Injection
> locking?
Not injection locking just the magic of cross corrrelation.
Only the phase noise that is common to both measurement  channels 
remains after sufficient averaging.
> Average in the power summer? Taking hundreds or thousands
> oscillators it seems possible to reach astonishing levels...
>
>    
Bruce

> On Sun, Dec 30, 2012 at 10:44 AM, Bruce Griffiths<
> bruce.griffiths at xtra.co.nz>  wrote:
>
>    
>> Tom Knox wrote:
>>
>>      
>>> Dual oscillators in Cross Correlated
>>> measurements will also produce a 3dB theoretical reduction in a Phase
>>> Noise measurement system.
>>>
>>>
>>>        
>> Since when?
>> Its way better than that.
>> I routinely achieve a PN floor below -170dBc/Hz (I don't have an OCXO with
>> a phase noise floor below ~ -175dBc/Hz) using a pair of oscillators each
>> having a PN floor (~ -150dBc/Hz) well above that
>>
>> Bruce
>>
>>
>>
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