[sdiy] Do digital filters still explode?

[karl dalen]

Well, i do remeber the word explode but if it was
Collin who said it, well i can be completely wrong.

The statement then included a explosion of overtones
and undertones, explosion such as in sudden boom of
aliasing, perhaps something similar to too deep and
drastic change of modulation index in a FM oscillator
,burst of squelchy noise.

Kd
 

> All due respect to Colin, but that's
> a pretty broad statement. I'd imagine that the stability of
> a filter under any operating conditions, including audio
> rate modulation depends to a high degree on the filter
> architecture as well as how one is modulating it.
> 
> I've seen some discussion of filter modulation in the past
> that revolved around different ways of interpolating between
> sets of filter coefficients. If the interpolated pole
> trajectories veer outside the unit circle of the z plane
> then you'll surely see instability. Designing interpolation
> techniques that avoid this is a topic that generates a lot
> of research papers.
> 
> Eric
> 
> On Feb 5, 2011, at 8:44 PM, karl dalen wrote:
> 
> > I think it was Collin Fraser who some years ago
> mentioned that
> > digital filters explode if they are audio rate
> modulated, have
> > that been solved now or do they still explode?
> > 
> > I recall that to some discussions on DSP list that had
> a thread
> > subject something like: What else are there left to
> emulate? 
> > 
> > Reg
> > Kd
> > 
> > 
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