I should mention that I do get a second peak in the frequency at around 200 Hz, which is exactly what I want. I just want to get rid of the maximum peak occurring at 0 Hz...
FFT is finding a max amplitude at 0 Hz
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Aimie
am 28 Jun. 2012
Kommentiert: Iftakharul alam
am 28 Jul. 2020
Can anyone explain why fft is giving a maximum amplitude at 0 Hz if the actual signal is pretty clear?
In my code, x is the signal as a function of time and r = length(x):
NFFT = 2^nextpow2(r);
X = fft(x,NFFT)/r;
Fs = 1/dt; % sampling frequency
f = Fs/2*linspace(0,1,NFFT/2+1); % frequency
A = 2*abs(X(1:NFFT/2+1)); % ampitude spectrum
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Honglei Chen
am 28 Jun. 2012
You need to remove the DC component first. Just do
x = x-mean(x)
or
x = detrend(x)
before applying FFT
2 Kommentare
Iftakharul alam
am 28 Jul. 2020
Dear Honglei Chen,
really appreciated to see you answer!
Thank you so much.
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