DTMF Signal Detection Using Goertzel Algorithm in MATLAB

Here is an example MATLAB code that uses the Goertzel algorithm to detect DTMF signals:

% Goertzel algorithm for DTMF signal detection

% Define the DTMF frequencies frequencies = [697 770 852 941 1209 1336 1477 1633];

% Define the sampling frequency and duration of signal Fs = 8000; % Hz duration = 0.5; % seconds

% Generate a DTMF signal with random digits digits = [1 2 3 4 5 6 7 8 9 0]; random_digit = digits(randi([1,length(digits)])); tone1 = sin(2pifrequencies(randi([1,4]))(0:1/Fs:duration)); tone2 = sin(2pifrequencies(randi([5,8]))(0:1/Fs:duration)); dtmf_signal = [tone1 + tone2, zeros(1,0.1*Fs)];

% Implement the Goertzel algorithm for each frequency for i = 1:length(frequencies) k = round((length(dtmf_signal)frequencies(i))/Fs); w = 2pik/length(dtmf_signal); coeff = 2cos(w); Q1 = 0; Q2 = 0; for j = 1:length(dtmf_signal) Q0 = coeffQ1 - Q2 + dtmf_signal(j); Q2 = Q1; Q1 = Q0; end power = (Q1^2 + Q2^2 - coeffQ1*Q2)/length(dtmf_signal); fprintf('Power at %d Hz: %f\n', frequencies(i), power); end

% Determine the detected DTMF tone [~,index] = max(power); if index <= 4 fprintf('Detected tone: %d\n', frequencies(index)); else fprintf('Detected tone: %d\n', frequencies(index-4)); end

In this code, we first define the DTMF frequencies and the sampling frequency and duration of the signal. We then generate a random DTMF signal with two tones, one from the low frequency group and one from the high frequency group.

We then implement the Goertzel algorithm for each frequency and calculate the power at each frequency. Finally, we determine the detected DTMF tone by finding the maximum power and identifying the corresponding frequency.

Note that this code is just an example and can be modified to detect DTMF signals in a variety of scenarios.