How to plot ifft for a frequency signal?
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Priyom Goswami
el 5 de Ag. de 2021
Comentada: Yazan
el 6 de Ag. de 2021
I've a .dat file (attaching the .mat file of that .dat file after converting, since this platform doesn't allow to upload .dat file while asking question) which represent the frequency spectrum of a vibration signal from a bearing having a sampling frequency of (fs=32768). How to convert the frequency signal to time domain signal. Please help.
3 comentarios
Scott MacKenzie
el 6 de Ag. de 2021
Editada: Scott MacKenzie
el 6 de Ag. de 2021
Have you tried? Please post the code you've attempted so far.
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Yazan
el 6 de Ag. de 2021
Editada: Yazan
el 6 de Ag. de 2021
clc, close all
fs = 32768;
fidx = z.Date23122013;
specOneSide = z.Time100351;
[fidx, idx] = unique(fidx);
specOneSide = specOneSide(idx);
fOneSide = (fidx./fidx(end))*fs/2;
subplot(1,2,1)
plot(fOneSide, specOneSide), xlabel('Frequency - Hz'), ylabel('Magnitude spectrum');
axis tight, title('One-sided spectrum');
specTwoSide = [flip(specOneSide(1:end)); specOneSide(2:end-1)];
N = length(specTwoSide);
f = -fs/2:fs/N:fs/2-fs/N;
subplot(1,2,2)
plot(f, specTwoSide), xlabel('Frequency - Hz'), ylabel('Magnitude spectrum');
axis tight, title('Two-sided spectrum');
sig = ifft(fftshift(specTwoSide));
figure,
t = (0:N-1)./fs;
plot(t, sig), axis tight, title('Signal');
xlabel('Time - sec'), ylabel('Amplitude');
5 comentarios
Yazan
el 6 de Ag. de 2021
Notice that the values of the Date23122013 (or your frequency axis points) are not unique. Also, for one value of Date23122013, you have sometimes multiple values of Time100351. My code uses the first appearing value of Time100351 for a given Date23122013 automatically, which is sometimes zero, but you might prefer otherwise. It is always a good idea to clean your data first.
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