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Old 08-03-2005, 12:05 PM   #1
jspenguin
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DTMF detection


I am writing a simple answering machine program and I need an algorithm to detect DTMF (dual-tone multifrequency) tones. I have a simple frequency detection algorithm, but it only works on single frequencies.
 
Old 08-03-2005, 04:59 PM   #2
Amadaeus09
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One approach is to include a Fast Fourier Transform (FFT) library to attach magnitude-of-presence to each frequency, then pay attention only to the 2 largest magnitudes.

Another, more efficient approach is to use the Goertzel Algorithm:
http://ptolemy.eecs.berkeley.edu/pap...www/node3.html


Last edited by Amadaeus09; 08-03-2005 at 11:54 PM.
 
  


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