c/goertzel/dtmf.sh

   1 #!/bin/bash
   2 #This is sample implementation of DTMF decoder using my C implementation of Goertzel Algorithm
   3 #This is not very efficient or precise, it's just proof of concept
   4 #Note that it's also quite tricky (but not imposible) to detect DTMF using microphone
   5 #You will probably need to tune treshold and mixer settings a bit...
   6 #I've had best results using dtmfdial (Linux software) and two soundcards connected directly using cable
   7 #Usage example: arecord 2>/dev/null | ./dtmf.sh
   8
   9 tresh=10
  10 last='';
  11 ./goertzel -n B -q -l -r 8000 -d 20 -t $tresh -f 697 -f 770 -f 852 -f 941 -f 1209 -f 1336 -f 1477 -f 1633 $@ | while read line; do
  12         #echo "$line";
  13
  14         #Get time
  15         pos="$(echo "$line" | cut -f 1)";
  16
  17         #Get values for each tone
  18         a="$(echo "$line" | cut -f 2)";
  19         b="$(echo "$line" | cut -f 3)";
  20         c="$(echo "$line" | cut -f 4)";
  21         d="$(echo "$line" | cut -f 5)";
  22         e="$(echo "$line" | cut -f 6)";
  23         f="$(echo "$line" | cut -f 7)";
  24         g="$(echo "$line" | cut -f 8)";
  25         h="$(echo "$line" | cut -f 9)";
  26
  27         #echo "$pos: $a $b $c $d $e $f $g $h";
  28         state="$a$b$c$d$e$f$g$h";
  29
  30         #Test if tones changed since last time
  31         #echo test "$state" != "$last"
  32         test "$state" != "$last" && {
  33
  34                 #DTMF Table
  35                 $a && {
  36                         $e && echo -n '1'
  37                         $f && echo -n '2'
  38                         $g && echo -n '3'
  39                         $h && echo -n 'A'
  40                 }
  41                 $b && {
  42                         $e && echo -n '4'
  43                         $f && echo -n '5'
  44                         $g && echo -n '6'
  45                         $h && echo -n 'B'
  46                 }
  47                 $c && {
  48                         $e && echo -n '7'
  49                         $f && echo -n '8'
  50                         $g && echo -n '9'
  51                         $h && echo -n 'C'
  52                 }
  53                 $d && {
  54                         $e && echo -n '*'
  55                         $f && echo -n '0'
  56                         $g && echo    '#'
  57                         $h && echo -n 'D'
  58                 }
  59
  60         }
  61
  62         last="$state"
  63
  64 done