chaos filter

[Kimmo Koli]

On Tue, 20 Oct 1998, Dr. Jörg Schmitz wrote:

> I'm thinking about a chaos-filter. 
> Imagine a pendulum, which is driven by another pendulum with a fixed 
> "input"-frequency. Then the other (driven)
> pendulum will behave chaotic (or not), depending on the relation of the
> input
> frequency and the frequency of the driven pendulum (which is determined
> by the length of the axis).
> This mechanical arrangement transformed into an analog computer must
> be a funny sounding filter if, for example, the length of the driven
> pendulum
> is controlled by the input frequency (i.e. input CV of the VCO), and the
> 
> relation between the input frequency and driven-pendulum-frequency by
> another
> CV, which is comparable to the filter amount.
> 
> Is something like that known, or any suggestions ?
> 
Well, in a the IEEE International Symposium of Circuits and Systems a few
years back was presented a chaos-oscillator based on a state variable
filter with an additional nonlinear feedback generated by a comparator with
hysteresis (by Edgar Sanchez-Sinencio's research group at Texas A&M). So it
is very much like a chaotic pendulum, indeed. 

You could have CV control for the linear Q-tuning feedback and a CV
controlled  comparator output voltage limiter and an independent CV
controlled hysteresis. Probably tweaking this chaotic filter may not be
very intuitive, though. I bet its more like programming a DX7 without any
hint of FM-synthesis theory. Anyway, the "filter" should at least  slightly
track with the main frequency CV.

Best regards, 
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   Kimmo Koli                         Helsinki University of Technology 
   kimmo at ecdl.hut.fi                  Electronic Circuit Design Laboratory
   http://www.ecdl.hut.fi/~kimmo      P.O.Box 3000
   Tel:  +358 9 451 2273              FIN-02015 HUT
   Fax:  +358 9 451 2269              Finland 
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