DTMF : Determining the pressed button on a phone

hey, I have a question that should be solved by MATLAB. I have a .wav file which consists of sound of the dialed phone buttons. Firstly, we should read that .wav file by wavread. And then we have to find the dialed numbers using MATLAB... How can I do that?

[Alll]

Let me ask my question in that way: assume that we have function which is sum of two different sinusoids. We have the sum function so how can we find the frequencies of added sinusoidals?

Answer 1

[Paulo Silva]

doc fft

If you have many combinations of frequencies you must first separate the wav file in pieces and analyse each one with the example code you see in the fft documenation, for each combination of two frequencies you will see two big spikes on the graph, the value in x axis is their frequency.

[Alll]

I could not apply the example code that I see on "doc fft" on my homework...

actually, when we read .wav file by wavread there are lots of discrete numbers in a matrice which specifies the sound file. When I take the DFT of that matrice I got again a matrice;this time consists of complex numbers. At that I got I cant go further....

[Paulo Silva]

http://www.mathworks.com/matlabcentral/fileexchange/29373-dtmf-tones-detection

[Alll]

thank you Paulo. I finally did it! I just separated that matrice in pieces as you said and then applied the code! It works.

[Eng Abeer]

 how did you do it ?
i have a assignment on it , please help