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Reply-to: Wolfgang Fritz <wolfgang.fritz@gmx.net>
To: linux-kernel@vger.kernel.org
From: Wolfgang Fritz <wolfgang.fritz@gmx.net>
Subject: Re: [Asterisk] DTMF noise
Date: Wed, 08 Jan 2003 17:30:54 +0100
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Wolfgang Fritz wrote:

[cut]

> 
> There exists a long text about DTMF detection somewhere on the net (I 
> may have the link in the office but I'm on vacation now). What I 
> remember is that a "correct" DTMF detection requires much more computing 
> power as the present i4l implementation needs (much longer audio samples 
> for the goertzel filter, a larger number of frequencies to check) and a 
> standard test procedure with a lot of test cases which are not available 
> to mortal humans (audio tapes from Bellcore IIRC)
>

The link below is not the text I mean above but shows an approach which 
is similar to the present i4l implementation but has some improvements 
which may be good enough for us.

http://www.mitsubishichips.com/press/dtmf0199e.pdf

> Wolfgang
>  >
[cut]




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