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DTMF decoder in Pd
Wednesday, November 25th 2015 11:15am
Tags: dtmf, pd, puredata, dialing

I was doing some digital housekeeping recently and came across an unfinished DTMF decoder that I started in Pd.  DTFM is also commonly known as "touch tone" and is a signaling system traditionally used over telephony systems (and things like ham radio repeaters).  I opened up the patch and found that it wasn't working quite right, so I tinkered and made something usable/releasable.

dtmf_decoder_pd.png
The help patch above shows decoding from a recording, live from the computers audio input (mic), and also from a fake DTMF dialpad that I made (which also uses my [dtmf~] abstraction).  If you're watching a movie or listening to the radio and hear some gold old-fashioned touch tones, you can now decode the digits using this Pd abstraction.  Good times.

Back in the 90s, I built several DTMF decoder circuits by hand, some that even interfaced wiht the computer's parallel port for logging.  Wow, that was a long time ago.  If you hunt around, I suppose you can still find DTMF decoder ICs, but they're certainly becoming harder to find.  I guess these days, it makes sense to use the $2000 general-purpose computer on your desk/lap to do that work instead of $10 in parts.  :-)

You can download this DTMF decoder (as well as my other DTMF related pd abstractions) over at my github repo: https://github.com/breedx2/pure-data.  Let me know if you find them useful!