Calculate energy from FFT
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Hi all,
I've generated FFTs for a set of signals at different deflections. I want to calculate total energy for some frequency ranges.
- So first I want to select the frequency ranges in which the dominant peaks of FFT are coming (each peak in each frequency range).
- Then calculate total energy in these frequency ranges.
Following is the code I'm using for getting FFT (also attached the set of time domain signals and deflection data):
[m, n]= size(amp); % amp- amplitude data
t=linspace(0,5000,n); % time
Fs=2000000;
for i=1:m
L = n;
NFFT = 2^nextpow2(L);
UT = fft(amp(i,:),NFFT)/L;
f = Fs/2*linspace(0,1,NFFT/2);
ft(i,:) = zeros(1,NFFT/2);
ft(i,:) = UT(1:NFFT/2);
mag(i,:) = 2*abs(ft(i,:));
end;
figure
for i=1:m
plot(f,mag(i,:))
hold on;
end;
xlabel('Frequency (Hz)','fontsize',12)
ylabel('Magnitude','fontsize',12)
title('Frequency Spectrum of recieved signals','fontsize',14)
axis([0,150000,0,4])
legend(arrayfun(@(deflection) ['Deflection = ',num2str(deflection),'\mum'],deflection,'Uni',0));
set(gcf, 'Color', 'w');
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