[time-nuts] OCXO phase noise

Javier Herrero jherrero at hvsistemas.es
Mon Feb 13 16:11:16 UTC 2012


I've an answer from Abracon. I had overlooked these plots: 
http://www.abracon.com/Precisiontiming/AOCJY%20Typ%20Phase%20Noise%20Plots.pdf

The answer is that we can expect for the 40MHz unit a phase noise 
performance half way between the 10MHz and 100MHz units performance. 
That is, compared with the 10MHz unit, roughly a 20dB increase at 10Hz, 
a more or less 12dB increase at 100Hz, 6dB at 1000Hz, and around 3dB 
from that point.

Regards,

Javier

El 13/02/2012 16:45, Javier Herrero escribió:
> 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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>
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Javier Herrero
Chief Technology Officer                  EMAIL: jherrero at hvsistemas.com
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