[time-nuts] Phase noise measurement with a scope

[Marek Peca]

>> (..) 
>> I have tried it with a very cheap one, Rigol 2-channel, originally 50MHz, 
>> reflashed to 100MHz. 2 signals, ref&measured, into Ch1, Ch2. Waveforms 
>> (2x500Msps) acquired, sinc() interpolated. Results: short-term single-shot 
>> jitter around 100ps RMS. Long-term was of no interest for my purpose now, 
>> so no observations here.
>> 
>> Therefore, it is almost of no use at all for higher precision needs.
>
> I was thinking about using a 4-channel scope with cross-spectrum averaging. 
> Look at the Timepod by John Miles for an example of the method. I'm trying to 
> guesstimate if the R&S RTO scope, perhaps with the aid of the I/Q option, is 
> capable of doing such measurements, and with what kind of performance.

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?

Regards,
Marek