Frequency Analysis $($Dual$-$Tone Multi Frequency $($DTMF$)$ Decoder$)$

Given a $.$wav file that contains a very noisy DTMF signal, your task is to build a DTMF decoder using any computer languages $($MATLAB is recommended$)$ to decode this signal. Make sure that the system is fully automatic. Although, a real$-$time approach is preferable, a batch processing for each segment is acceptable.

Hints:

Here is how DTMF works. It generates $2$ frequencies for each key pressed. For example, when an $"8"$ key is pressed, the DTMF signal consists of $852$ and $1336Hz$ components. A keypad and the $8$ frequencies are shown below.

Z

Z

Z

Z

Hints: $($cont$.)$

Listen to this wave file should help.

Segmentation for each segment $($may use a thresholding, etc.$)$

For each segment, do the frequency analysis.

Make a decision based on the previous step $($may use the nearest distance, etc.$)$

Note:

Discussion section of your report is very important. Make sure you write down everything you observe. Wrong observations are better than none.