# FFT of Signal doesn´t work well

조회 수: 1(최근 30일)
Cedric Burkhart 2021년 8월 30일
편집: Cedric Burkhart 2021년 8월 30일
Hi,
I would like to have a FFT of a constant signal with two Dirac jumps.
My signal is correct, but my FFT shows nothing. May somebody could help me?
It´s the following code:
t = [1:361] ; % in Grad, Gesamtumdrehung sind 360°
f(t(1):t(end)) = 0; % f = Signal
% Magnets
N = 23; % Amount of magnets
n = 2; % selected magnets
a = 360/n ; % distance between magnets
% Signal 1 = Dirac
tsprung = 20;
tsprung2 = tsprung + a;
f(tsprung)= 1;
f(tsprung2)= f(tsprung);
subplot(211);
plot (t,f);
xft = fft(f);
xabs = abs(xft);
subplot(212);
plot (xabs);
set(gca, 'XTick',[0:20:360])
set(gca, 'YTick',[0:0.1:1])
xlabel ('Position der Magneten in Grad');
ylabel ('Stoß');
legend ('Signal');
THANKS A LOT !

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### 답변(1개)

KALYAN ACHARJYA 2021년 8월 30일
xabs(2nd Plot) is the absolute of fft ??
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Cedric Burkhart 2021년 8월 30일
Yes it should show the absolut numbers of the fft, but if it works without the abs then it will be good as well.
I just wanna see how the frequency-spectrum is before and after the dirac jump.

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