[time-nuts] Phase noise at 1-100Hz

Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Apr 7 08:49:03 UTC 2011


Javier Herrero wrote:
> Hello,
>
> I will need to measure the phase noise of a 35MHz oscillator in the 
> range of 1 to 100Hz (well... and also at a higher range but this is no 
> problem), and I would like to know about the different alternatives. I 
> would like not to have to mess too much with mixers and soundcard 
> sampling, if possible :)
>
> I think that the HP 5372A with opt 040 is able to do that, is this 
> right and worthy? If so, opt 040 is a pure software option or requires 
> also additional hardware? Would be possible also with a 5370A and 
> software processing of the raw data? Any other alternatives?
>
> Thanks! Regards,
>
> Javier
>
The 5372A or 5370A will only suffice if the phase noise is sufficiently 
high.
They are likely to be too noisy by several orders of magnitude for a 
good crystal oscillator.
However they may suffice for something like a noisy ring oscillator or 
even a low Q LC oscillator.
There's also the question of defining the bandwidth so as to avoid 
folding high frequency phase noise into the measurement when the phase 
sampling rate is relatively low as it will likely be with a 5370A..

Bruce




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