[time-nuts] OCXO phase noise

Javier Herrero jherrero at hvsistemas.es
Mon Feb 13 15:45:10 UTC 2012


Thanks for your answers, Magnus and John. For now, I will take the 12dB 
value as a starting point until further confirmation.

Regards,

Javier

El 13/02/2012 10:32, Magnus Danielson escribió:
> On 02/13/2012 10:16 AM, John Miles wrote:
>>> That is exactly my thinking, but I was looking for a second opinion :)
>>> We have anyway asked Abracon for pn data on the 40MHz version to be
>>> sure.
>>
>> Most likely, the PN improvement will be somewhat better than the 
>> expected 12
>> dB close to the carrier, and somewhat worse than expected (if you see 
>> any
>> improvement at all) farther out.
>>
>> The corner frequency that separates "close in" and "farther out" will be
>> device-specific,  but it'll probably happen between 100 Hz and 2 kHz.
>
> A more proper analysis would separate the effects of oscillator Q, 
> resonator loop noise and the buffer noise and then scale them 
> accordingly.
>
> Assuming the same Q (which isn't correct) the oscillator core 1/f^2 or 
> 1/f^3 flips up on. The buffer noise then masks on top of that.
>
> Cheers,
> Magnus
>
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