> > wouldn't it be easier to check for zerocrossings?
>
> This would assume a perfect sine wave for both tones. The bad thing
> about zero crossing is that even the tiniest amount of noise
> completely ruins it, and then you're looking at second derivatives,
> which are also dependent upon signal
On Thu, Jul 25, 2002 at 10:45:27AM -0400, Paul Davis wrote:
> >Hello to all,
> >
> >who has already done DTMF recognition with ALSA ( OSS )?
> >I searched for examples in google, but I have found that
> >only in TODO lists ;-(.
> >
> >Is this so difficult or why doesn't exist anything about that?
> wouldn't it be easier to check for zerocrossings?
This would assume a perfect sine wave for both tones. The bad thing
about zero crossing is that even the tiniest amount of noise
completely ruins it, and then you're looking at second derivatives,
which are also dependent upon signal quality. Th
On Thu, Jul 25, 2002 at 10:45:27AM -0400, Paul Davis wrote:
> >who has already done DTMF recognition with ALSA ( OSS )?
> >I searched for examples in google, but I have found that
> >only in TODO lists ;-(.
> >
> >Is this so difficult or why doesn't exist anything about that?
Please have a look a
wouldn't it be easier to check for zerocrossings?
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>Hello to all,
>
>who has already done DTMF recognition with ALSA ( OSS )?
>I searched for examples in google, but I have found that
>only in TODO lists ;-(.
>
>Is this so difficult or why doesn't exist anything about that?
its a relatively trivial FFT problem. use FFTW to analyse the signal,
the
Hello to all,
who has already done DTMF recognition with ALSA ( OSS )?
I searched for examples in google, but I have found that
only in TODO lists ;-(.
Is this so difficult or why doesn't exist anything about that?
regards
Philipp Vollmer
-
