Mark Spencer wrote:
> The DTMF detector in the linux kernel is fairly simplistic and doesn't do
> many relative energy tests. The Zapata library has a much better tone
> detector, but it is FP, and so would have to be made fixed point. If
> nothing else, it may provide some lessons for the ISDN folks.
I remember that a good DTMF decoder can be very simplistic: DTMF was designed
for that.
The idea is:
- separate the high tones from the low tones.
- amplify clip the high band and the low band separately
- run the tone decoders on the clipped signals
The clipping stage would make sure that only relatively pure tones will trigger
the detector.
See also http://groups.google.com/groups?selm=7462%40accuvax.nwu.edu
Thomas
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Tue Jan 07 2003 - 22:00:36 EST