Design a DTMF decoder, which is capable of decoding a three-digit extension number. Note that a three-digit extension number is composed of three consecutive DMTF tones based on the following table:

1336 Hz 1477Hz 1209 Hz

697Hz 1 4 7

852Hz 2 5 8

770Hz 3 6 9

Your decoder should rely mainly on SIMULNK blocks for its functionality. Signals can be loaded from the workspace and the result can be saved to the workspace. However, the decoder's main functionality must be via SIMULINK blocks. Thus, the input to the decoder can be any signal generated based on the above table and the output should be the corresponding three-digit extension number.