Re: IIR vs. FIR filters
Re: IIR vs. FIR filters
- Subject: Re: IIR vs. FIR filters
- From: Michael Ashton <email@hidden>
- Date: Tue, 10 Dec 2002 15:02:02 -0700
One of the simplest ways, but often not the
best solution for an Nth order FIR filter is to take the first
N samples of the impulse response from the IIR filter
(these first N samples can be easily generated in C code by passing
an impulse - first sample 1.0, following samples 0.0 - through
the IIR code). Improvements can be made by windowing this result.
I like this idea. Might this not sidestep some of the stability issues
one gets with IIRs?
Only one problem with FIRs though. Say you want to simulate a tunable
Moog-style / 4-multiply filter. Isn't it easier to do that with an IIR?
Perhaps you could do multi-rate processing of some sort through an FIR
to get the tuning, and run a feedback loop for resonance .. dunno. I'll
bet somebody's done this before.
It occurred to me just now that a slick way to get around the
biquad-warping problem for digital 4-multiply filters might be to take
the impulse response of a continuous-time circuit and do convolutions
... hmm ...
Lots of memory though ..
Maybe I should bring this up on a computer-music list :)
----
Michael Ashton <email@hidden>
"Turning off Rendezvous to improve security is like having a company
policy that every employee will be hit in the face with a baseball bat
every day when they come to work in the morning, to discourage thieves."
-- Stuart Cheshire, the Rendezvous FAQ
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