Marek Peca wrote:
The cross-spectrum averaging does indeed do just that, relying on two ADCs to produce uncorrelated noise, which can be averaged out.(..) 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?
Or am I misunderstanding your point? Cheers Stefan
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