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Path: utzoo!linus!philabs!cmcl2!seismo!harvard!talcott!panda!teddy!rdp
From: rdp@teddy.UUCP
Newsgroups: net.audio
Subject: Re: David Mohler is completely correct
Message-ID: <1167@teddy.UUCP>
Date: Tue, 20-Aug-85 10:00:51 EDT
Article-I.D.: teddy.1167
Posted: Tue Aug 20 10:00:51 1985
Date-Received: Fri, 23-Aug-85 05:24:48 EDT
References: <19@drune.UUCP> <4162@alice.UUCP> <4164@alice.UUCP>
Reply-To: rdp@teddy.UUCP (Richard D. Pierce)
Organization: GenRad, Inc., Concord, Mass.
Lines: 21

In article <4164@alice.UUCP> jj@alice.UUCP writes:
>
>Just as an aside, I'm interested in those filters that
>Mohler has invented that have no ringing.  It's odd,
>but I've written a few papers on filter design, a few more
>on audio, etc, and all of the filters I've seen worked because
>they had "ringing".  Funny thing, a filter with no ringing 
>passes just perfectly well as NO FILTER.
>
>Check out Rabiner and Gold, Oppenheim and Schaeffer, or any
>other basic text.
>

Correct me if I am wrong (and I am sure the righteous amongst certainly
will, in a most vehement manner), but do not filters of the Bessel
persuation (or some other forms of constant time delay) succeed in
filtering without ringing?

Also, I have yet to see any evidence of a first-order filter even having
overshoot, much less ringing, or is something wrong with my scopes, 
resistors, capacitors and books?