[sdiy] Moogey jitter

[harrybissell]

I'd suggest that ~we~ trigger the scope with the actual reset pulse
of the VCO. That should eliminate a lot of uncertainty.

Best thing to do from there would be to run a really really really
fast counter, and store the count for every cycle.  

Then there would be very little doube if the system was
jittering.

Another way would be a fast comparator set at 1/2 the ramp peak
amplitude... but if the voltage was not stable it would be
a bad measurement

H^) harry

mark verbos wrote:
> 
> This low frequency noise that effects the reset comparator and the
> integrator slope would also effect the DC location of the saw wave from
> the core output , wouldn't it?
> 
> I noticed some "wavering" of my analog VCO waves and it gave me an idea
> a while back. I opened up Pro Tools and made some raw waves with the
> signal generator. Then, with the pencil tool, at a huge magnification, I
> drew in a randomly moving dc offset on another track. I then mixed the
> waves together, along with some of this red or brown noise. That didn't
> sound like anything at all. However, when I then ran that mixed signal
> through distortion, or waveshaping or some other effects these randomly
> varying DC offsets really added to the analog-ness of the sound. I don't
> know if it would qualify as "Moogy" but it did sound interesting. I also
> tried using triangle waves that I pitched down 4 or more octaves. This
> also had an interesting effect.
> 
> Mark
> 
> René Schmitz wrote:
> > Hi Ian and all,
> >
> > Ian Fritz wrote:
> >
> >> Conclusion:  Any phase beating effects are going to occur over longer
> >> time scales due to drifting and wandering, not the bogus phase jitter
> >> that Kevin claims.
> >
> >
> > Absolutely.
> >
> > But there is a problem with denominations here. I'd call this frequency
> > fluctuations. Or like Magnus: wandering, quicker than drift, but slower
> > than jitter. (You might even think of drift and jitter being the same
> > thing, it merely depends on the timescales on which you observe.)
> > And I don't see how small fluctuations of momentary frequency away from
> > the average frequency would not change the beating pattern. Provided the
> > frequency of these fluctuations is low enough, that an effect can
> > accumulate over these timescales (several seconds).
> > Kenneth's sample is too short IMO to really be useful in analysing that.
> >
> > Cheers,
> >  René
> >