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From: Roy Sigurd Karlsbakk <roy@karlsbakk.net>
To: Matti Aarnio <matti.aarnio@zmailer.org>,
	Kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: i4l dtmf errors
Date: Sat, 14 Dec 2002 15:54:29 +0100	[thread overview]
Message-ID: <200212141554.29354.roy@karlsbakk.net> (raw)
In-Reply-To: <20021212121004.GC32122@mea-ext.zmailer.org>

>   Quick reading of  drivers/isdn/isdn_audio.c(*)  shows that it does use
>   fixed-point Görtzel (Goertzel in english) algorithm for detecting
>   tones, but it does _not_ do comparison of received overall signal
>   power vs. detected DTMF tone powers.
>
>   When there is signal power outside the DTMF channels, signal should
>   not be detected.  Also, DTMF tone powers should be roughly equal,
>   and exactly two tones should be present for valid detection.
>
>       http://www.numerix-dsp.com/goertzel.html
>
>   Adding those power tests should be fairly trivial, but I leave it
>   to Somebody Else...

Is there a 'somebody else' (perhaps the isdn maintainer?) that have time to 
look at this?

thanks

roy
-- 
Roy Sigurd Karlsbakk, Datavaktmester
ProntoTV AS - http://www.pronto.tv/
Tel: +47 9801 3356

Computers are like air conditioners.
They stop working when you open Windows.


  reply	other threads:[~2002-12-14 14:46 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-12-12 10:45 i4l dtmf errors Roy Sigurd Karlsbakk
2002-12-12 12:10 ` Matti Aarnio
2002-12-14 14:54   ` Roy Sigurd Karlsbakk [this message]
2002-12-14 20:51 ` Wolfgang Fritz
2002-12-14 23:14   ` Kai Germaschewski
2002-12-16 17:44     ` [PATCH] (Was: i4l dtmf errors) Wolfgang Fritz
2003-01-06  9:57       ` Roy Sigurd Karlsbakk
2002-12-16 11:07   ` i4l dtmf errors Roy Sigurd Karlsbakk

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