Find maximum peaks in fft and power spectral density function

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marcusbarnet 2018-3-29

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https://ww2.mathworks.cn/matlabcentral/answers/391386-find-maximum-peaks-in-fft-and-power-spectral-density-function

评论： marcusbarnet 2018-3-29

prova1.mat

I have an array ( raw_acceleration) of 1600 elements acquired every 10 seconds at 160Hz from a sensor. I use this array to calculate the fft and the Power Spectral Density and it works very well:

Fs=160;
raw_acceleration = u;
N = length(raw_acceleration);
xdft = fft(raw_acceleration);
xdft = xdft(1:floor(N/2+1));
psdx = (1/(Fs*N)) * abs(xdft).^2;
psdx(2:end-1) = 2*psdx(2:end-1);
freq = 0:Fs/length(raw_acceleration):Fs/2;
plot(freq,10*log10(psdx))
grid on
xlabel('Frequency (Hz)')
ylabel('Power/Frequency (dB/Hz)')

I obtain this plot:

As you can see, I obtain four peaks centered around four different frequencies.

I would like to have a Matlab code which is able to automatically find these four maximum peaks and their frequency. At the moment, I always need to plot the graph and manually detect the maximum peak and its frequency.

Is there any way to do this by code? I hope you an help me.

I attached a sample of raw_acceleration array.