what is the median frequency matlab code?

Prashant Kumar answered . 2024-12-21 00:19:44

You need to use the cumtrapz function:

t = ...;                                                % Time Vector
s = ...;                                                % Signal Vector

Fs = 1/mean(diff(t));                                   % Sampling Frequency
Fn = Fs/2;                                              % Nyquist Frequency
L = length(t);

FTs = fft(s)/L;
Fv = linspace(0, 1, fix(L/2)+1)*Fn;                     % Frequency Vector
Iv = 1:length(Fv);                                      % Index Vector

CumAmp = cumtrapz(Fv, abs(FTs(Iv)));                    % Integrate FFT Amplitude
MedFreq = interp1(CumAmp, Fv, CumAmp(end)/2);           % Use ‘interp1’ To Find ‘MF’

figure(1)
plot(Fv, abs(FTs(Iv))*2, '-b')                          % Plot FFT
hold on
plot(Fv, CumAmp, '-g')                                  % Plot Cumulative Amplitude Integral
plot([MedFreq MedFreq], ylim, '-r', 'LineWidth',1)      % Plot Median Frequency
hold off
grid

I tested this with an archive signal, so the code works. It should work with your signal without modification. You can delete the plotting of the cumulative amplitude integral (green line), since it is there only to illustrate that the median frequency is calculated correctly.

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