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From: bill@flutter.tv.tek.com (William K. McFadden)
Newsgroups: sci.electronics
Subject: Re: Discrete Time Filter for Audio
Keywords: Audio, filter, discrete
Message-ID: <9918@orca.wv.tek.com>
Date: 22 Jan 91 06:26:34 GMT
References: <1991Jan21.131003@sdd.hp.com>
Sender: news@orca.wv.tek.com
Organization: Tektronix TV Products
Lines: 26

In article <1991Jan21.131003@sdd.hp.com> kirk@sdd.hp.com (Kirk Norton) writes:
>I have done some
>work with discrete time control systems and am familiar with a few
>different methods:  impulse invariant, step invariant, bilinear (with
>and without freq. prewarping), and pole-zero mapping.  Are any of these
>methods commonly used for audio filter design?  Does it depend on the
>desired frequency response characteristics of the filter?

I've designed filters using all of the above methods except pole-zero
mapping.  In every case, the bilinear transform with frequency
prewarping was at least as good as the other methods.  In most cases it
was a lot better (this was especially true for high pass filters).
You'll find, by and large, that this is the preferred method for IIR
filter design.

You are probably also aware of FIR filters, which have no feedback and
linear phase response.  They are more computationally intensive than
equivalent IIR filters, but are used a lot because everybody is so
concerned about phase these days.

(FIR=finite impulse response, IIR=infinite impulse response)
-- 
Bill McFadden    Tektronix, Inc.  P.O. Box 500  MS 58-639  Beaverton, OR  97077
bill@videovax.tv.tek.com,     {hplabs,uw-beaver,decvax}!tektronix!videovax!bill
Phone: (503) 627-6920       "The biggest difference between developing a missle
component and a toy is the 'cost constraint.'" -- John Anderson, Engineer, TI