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Path: utzoo!linus!decvax!harpo!eagle!karn
From: karn@eagle.UUCP (Phil Karn)
Newsgroups: net.audio
Subject: Filter orders
Message-ID: <1081@eagle.UUCP>
Date: Wed, 31-Aug-83 02:11:32 EDT
Article-I.D.: eagle.1081
Posted: Wed Aug 31 02:11:32 1983
Date-Received: Wed, 31-Aug-83 23:12:18 EDT
Lines: 10

The comment about different attenuation slopes for Butterworth
and Bessel filters is incorrect.

The ultimate attenuation of a high or low pass filter is 6 db/octave/order,
regardless of the filter type.  This attenuation is determined by the
highest power of S (complex frequency) appearing in the transfer function,
and this number is also the filter order.  Only the response "near" cutoff
is changed by changing the coefficients of the lower order terms.

Phil