Variable ramp again

[Don Tillman]

   Date: Wed, 4 Aug 1999 13:26:53 +0200
   From: mbartkow at ET.PUT.Poznan.PL

   It's very simple, though. Consider a nonsymmetrical pulse wave, e.g
   with PW=10%.  Removing the DC offset means that a constant value is
   added which causes that the areas under the negative "half" and the
   positive "half" are equal. 

This makes a great thought experiment, but it won't work in practice.

As a thought experiment it tells us that the sound of a variable duty
cycle sawtooth is going to be like a PWM square wave through an
integrator, adjusting for level and offset (which we can do also do in
our head).  The harmonics will all be the same as a PWM square wave,
there will just be fewer of them.  Great.  Not a breakthrough or
anything, but at the far end of the range those buzzy thin little
pulses will now sound like fat sawtooth waves, making me think it has
a lot of potential.

But the real interesting things happen when we dynamically modulate
the duty cycle, or FM modulate the duty cycle with an audio source, or
cross modulate a couple of these ocillators.  Our thought experiment
knows to give up at this point.  And this is exactly where a dc
restoration circuit and an amplitude adjustment circuit would also
fail.  

  -- Don