dtmf_goertzel.m

用dsp解压mp3程序的算法

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% dtmf_goertzel.m - This program generates bin number of DTMF tone
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clear all; close all;

% Low freq group: fL = 697, 770, 852, 941 Hz

fL = [697 770 852 941];

% High freq group: fH = 1209, 1336, 1477, 1633 Hz

fH = [1209 1336 1477 1633];

Fs = 8000;
N = 256;        % 256-point DFT

kL = ceil ((fL*N)/Fs)
kH = ceil ((fH*N)/Fs)
index = [kL kH];

load tx_data_5;

% Use Goertzel algorithm to extract the digit info

mag_low = abs(goertzel(HT(1:N), kL)).^2;
[y_low,index_low]= max(mag_low);

mag_high = abs(goertzel(HT(1:N), kH)).^2;
[y_high, index_high] = max(mag_high);


% Select the keypad

key = [ '1' '2' '3' 'A'; '4' '5' '6' 'B'; '7' '8' '9' 'C'; '*' '0' '#' 'D'];
fprintf('The key detected is %c',key(index_low, index_high));