Interesting Paper available on Moog VCF
Erik The ViKing
E.G.P.Schuijers at stud.tue.nl
Sat Sep 21 14:24:13 CEST 1996
>
> Date: Fri, 20 Sep 1996 12:22:20 +0100 (CET)
> From: "Erik Schuijers" <E.G.P.Schuijers at stud.tue.nl>
>
> What technique many companies use these days is called sigma-delta
> conversion.
>
> I can't see how sigma-delta conversion would help here.
>
I didn't say it would help.... It's just a sneaky way of getting a high-res
AD-conversion.
The anti-aliasing filter could be very simple thanks to the high
sampling-frequency.
Note: in the decoding part of a sigma-delta conversion there's a sum of
quantisation errors.
> Date: Fri, 20 Sep 1996 13:15:51 -0400 (EDT)
> From: Eli Brandt <eli at ux3.sp.cs.cmu.edu>
>
> Take the case where we've got harmonic partials and they're all in
> phase. So the input signal x(t) is a sum of cos(kt) terms, out to K.
> Each term a_k cos(kt) can be expanded, using the Chebychev* T_n, to a
> degree-k polynomial in cos(t). Waveshaping their sum with a degree-D
> polynomial gives one of degree-KD. Then translate each cos^n(t) back
> to a sum of cos(kt) terms, k<=n. So we have a sum of cos(kt) terms,
> k<=KD.
>
Hmmm, this is a nice method for making samples. But I don't think this would
work in real-time. (Unless you'd want to give up on your P6-200!!!)
Erik
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