[sdiy] oscillator jitter / phase noise

[Magnus Danielson]

From: René Schmitz <uzs159 at uni-bonn.de>
Subject: Re: [sdiy] oscillator jitter / phase noise
Date: Fri, 04 Jun 2004 12:42:01 +0200
Message-ID: <40C051F9.4000009 at uni-bonn.de>

> Hej Magnus et al.,

Hej René!

> Magnus Danielson wrote:
> 
> >>Since most people do not have access to old gear, audio sampling
> >>would be also interesting. It is easier to obtain a DAT tape
> >>of a pure VCO recording then to get hold on the machine.
> > 
> > 
> > The information is essentially lost, so for this purpose it is not usefull.
> 
> 
> I would say, that if it isn't recordable with a DAT (or the likes), it 
> shouldn't be audible on a recording. I think it would be futile to 
> examine a process that is masked by the common recording methods.

That would be to over-interprent what I was saying. What I mean to say is that
it is much harder to retrieve the phase modulation waveform when digitized.
It is still encoded in the sampled waveform, but in a form which is harder to
retrieve than having the raw waveform into a dedicated instrument.

> But I would doubt that it can't be captured by audio rate sampling. I 
> think the zero crossings might not be accurately reproduced, but any 
> jitter would also pop up on the slope (think sawtooth) as well, probably 
> too tiny to accurately trigger on that though.

The phase modulation is distributed throughout the full cycle, but a high
resolution measurement is not possible by simple means as we can do when we
have intact through-zero slopes.

Cheers,
Magnus