Subject: Re: [linux-audio-dev] Amateur Radio Repeater - Audio control via soundcard
From: vincent_AT_ulyssis.org
Date: Sat Apr 07 2001 - 00:28:41 EEST
[cut]
> I have read the information about full duplex and low latency. I think
> those things are within my ability. The part I am particularly stumped
> about is tone detection. This is not a signal modification DSP kind of
> effort, just detecting whether a particular tone pair (DTMF) or subaudible
> tone is part of the audio input.
> I would appreciate any leads or advice you all might have for me.
[cut]
This might be oversimplistic, but it could help you:
Compute a Discrete Fourrier Transform of your input, so you can check whether
some frequency (some DTMF tone) is in it.
Rumors go that the fast Fourrier Transform of the West is the best (I have
seen this transform being used in some LADSPA plugin I think ...)
http://www.fftw.org/
On that website also are a load of links to info about Discrete Fast Fourrier
Transforms ...
Anyway, this is just a small hint, hope it helps
Kind Regards
Vincent
This archive was generated by hypermail 2b28 : Sat Apr 07 2001 - 00:52:07 EEST