How to remove Silence from an that has DTMF tones in it?

Question

Soniya Rudani 2014-7-22

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https://ww2.mathworks.cn/matlabcentral/answers/142935-how-to-remove-silence-from-an-that-has-dtmf-tones-in-it

编辑： Walter Roberson 2021-11-21

The input to my file is are the DTMF digits but since it has silence intervals in it, i.e., 'beep',silence,'beep',silence, and due to this silence when fft is taken,The system cannot identify the correct frequencies of dtmf so how can i remove this silence?

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Answer 1

sandeeep jan 2017-10-4

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https://ww2.mathworks.cn/matlabcentral/answers/142935-how-to-remove-silence-from-an-that-has-dtmf-tones-in-it#answer_284234

编辑：Walter Roberson 2021-11-21

在 MATLAB Online 中打开

Fs = 8000;
t = 0.25;
N = 1:ceil(t*Fs);
% define DTMF:
R = [697,770,852,941]; % Hz, rows
C = [1209,1336,1477]; % Hz, columns
[Ra,Ca] = meshgrid(R,C); % Hz, all
Rb = 2*pi*(Ra(:)/Fs);
Cb = 2*pi*(Ca(:)/Fs);
T = sin(Rb*N) + sin(Cb*N);
% get user input:
J = '123456789*0#';
% subplot is by row
I = input('Enter keys/s [0:9*#]: ','s');
assert(all(ismember(I,J)),'An invalid key was entered')
% plot and play:
for k = 1:numel(I)
    X = strfind(J,I(k));
    subplot(4,3,X);
    plot(T(X,:));
    xlabel(sprintf('KEY%s',I(k)))
    sound(T(X,:));
    pause(0.5);
end