[time-nuts] Phase noise measurement with a scope

[Chris Albertson]

My dim memory says there is some analog way to multiply the phase noise.
 What does that?   Then it might be easier to measure.


On Wed, Jun 12, 2013 at 2:36 PM, Marek Peca <marek at duch.cz> wrote:

> My point was, that DSO is basically an ADC. Therefore, there is some
>>> amount of noise, nonlinearity and drift, limiting the jitter measurement.
>>> Do you think any method can dig more information from given data than
>>> sinc() interpolation and zero-crossing computation?
>>>
>>
>  The cross-spectrum averaging does indeed do just that, relying on two
>> ADCs to produce uncorrelated noise, which can be averaged out.
>>
>> Or am I misunderstanding your point?
>>
>
> Nothing against that. It depends on what noise level after averaging you
> require. I only posted my experience with a very low-quality DSO, which has
> 100psRMS single-shot. Using sinc() interpolation, but my point was, that I
> suppose there is no way to obtain better single-shot performance than this.
> To average out 100psRMS to, say, 1psRMS, it would require 10^4 edges (under
> the assumption, that the 100psRMS is well behaved noise).
>
> What performance it could yield with a better scope? I hope I'll try
> LC584AL some day, I guess it might give sth like 10psRMS single-shot...
>
>
> Regards,
> Marek
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-- 

Chris Albertson
Redondo Beach, California