MATLAB: How to combine signals for each digit in telephone number (dtmf) to form one continuous signal

digitsdtmfplotsignals

Hello. I have this problem: How to combine signals for each digit in telephone number (dtmf) to form one continuous signal, but each digit signal should be separated by silence period? I could manage to plot for each digit, but dont know how to combine them into one? I attached my source code. And I have to get signal like in the picture

Best Answer

Set

 y = []; 
 silence = zeros(1,numel(time_vector);

before the for loop and then use

y = [y y_high+ y_low silence]

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MATLAB: Plotting more than one DTMF frequencies on a graph

Okay, now that your question is clearer to me, I think this is what you want:

t = 0:1/32798:0.25-1/32798;
x2 = sin(2*pi*1336*t) + sin(2*pi*697*t);
x7 = sin(2*pi*1209*t) + sin(2*pi*852*t);
int_of_silence = .1; shift = t(end)+ int_of_silence;
plot(t, x2, 'b', t+shift, x7, 'b',  [t(end) t(end)+int_of_silence], [0 0], 'b', t+2*shift, x2, 'b', 2*[t(end) t(end)+int_of_silence], [0 0], 'b')

You see the trick is shifting the time axis for each segment by the right amount, I called it shift. The [t(end) t(end)+int_of_silence], [0 0], 'b' part is only to draw a line at 0 between segments.

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You have

speech = ('coch4.wav');
speech2 = speech;

So your speech2 filename is the same as your speech filename.

[y,Fs]=audioread(speech2); %don't use wavread or audioread

So you read from coch4.wav via speech2 filename

audiowrite(speech, speech_trimmed, 44100);

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Best Answer

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