On Sat, 2012-04-07 at 08:21 -0400, V G wrote:
> Hi all,
>=20
> What algorithms/filters/whatever would I start looking into to use a
> microcontroller/FPGA/digital ICs/analog components to detect the frequenc=
y
> of a single audio source such a as an electric guitar input? I don't real=
ly
> even need the actual frequency number, I just somehow need to convert the
> input wave into a square wave/pulse that can be used to pulse an LED, for
> example.
>=20
> I used my oscilloscope to look at the signal generated by the guitar, and
> it's pretty clean, but it:
>=20
> 1. doesn't look exactly like a sin wave
> 2. decreases in amplitude over time (and becomes almost exactly like a
> sawtooth wave at low amplitudes)
>=20
> How would I go about extracting the frequency out of this, or getting a
> clean pulse corresponding to the frequency (like a square wave, or
> whatever)?

Do a transform in to the frequency space (DFT or others depending on
what hardware you've got) and usually just select the biggest peak.

You might have program a little more intelligence then that if you the
guitar is being put through distortion stuff, but I doubt it.

If you're update rate is low (say 5Hz) you have lots of options.

TTYL

--=20
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