[time-nuts] ensemble oscillators for better stability
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?
> Moreover: what is the physical principle that can explain this? Injection
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...
> 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
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