使用Matlab从WAV文件中分离DTMF信号 [英] Splitting a DTMF signal from a wav file using Matlab

问题描述

问题出在这里:我有一个wav格式的DTMF信号，我必须确定它已编码的数字序列.我必须在Matlab中使用快速傅立叶变换来执行此操作，这意味着我使用wavread读取了wav文件，并标识了每个相隔40ms或更长时间的数字.

Here is the context of the problem: I have a DTMF signal in wav format, I have to identify the number sequence it has encoded. I must do so using fast fourier transform in Matlab, implying that I read the wav file using wavread and to identify each number that is seperated by 40ms silence or more.

到目前为止，这是我的代码:

Here is my code so far:

[signal, fs] = wavread( 'C:\Temp\file.wav' );  % here, fs = 8000Hz

N = 512;                    
T = 1/fs;                   
L = length( signal )        
samples = fs / 1000 * 40    
windows = floor(L / samples) 
t = (1:L)/fs;

figure(1), plot(t, signal);

这是figure 1的样子，这就是从wav读取的信号:

Here is what the figure 1 looks like, that is the signal read from the wav:

如何有效地将信号分成几部分，以便可以分别对10个部分分别进行FFT解码，以解码相应的数字?

How can I effectively split the signal into pieces so that I can then do an FFT on each of the 10 pieces seperately to decode the corresponding numbers?

推荐答案

这对我有用:

windowSize = 256;   
nbWindows = floor(L / windowSize);

for i=1:nbWindows
    coeffs = fft(signal((i-1)*windowSize+1:i*windowSize));    
    plot(abs(coeffs(1:N)));
    waitforbuttonpress
end;

通过这种方式可以将窗口移至输入信号的结尾

This way it is possible to shift the window until the end of the input signal

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