The FFT plot does not shows up, it is empty
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I want to get FFT of a vibration signal that is rrecorded in csv file. Fortunately, the figure with the plot of the signal displays correct data. However, when I try to perform fft, the figure is empty. I do not know of it is because of my code, the signal (or csv), or the MATLAB settings. Could you please help me to solve the problem.
Here is the code:
data = readtable('scope_0.csv');
column2 = data.Var2;
figure;
plot(column2(1:2000));
fs = 40000;
l1 = length(column2);
fft_result = fft(column2, l1);
fft_abs = abs(fft_result);
t = 0:1/fs:2000/fs;
freq = 0 : (1/t(end)) : fs/2 - (1/t(end));
figure;
plot(freq, fft_abs(1:length(freq)));
And the figures:
2 个评论
Simon Chan
2023-6-10
Could you restart MATLAB and try to run it again?
If it is still not successful, could you attach your data so that we can try to reproduce the same problem or not.
Valeriya Kostyukova
2023-6-10
采纳的回答
Star Strider
2023-6-10
1 个投票
Perhaps:
data(isinf(data)) = NaN;
data = fillmissing(data, 'linear');
since there may be a NaN or Inf value in ‘data’ that is causing the problem.
It would help to have the ‘scope_0.csv’ file.
4 个评论
Valeriya Kostyukova
2023-6-10
Here you go —
data = readmatrix('scope_0.csv')
data = readtable('scope_0.csv');
column2 = data.Var2;
column2(isinf(column2)) = NaN;
column2 = fillmissing(column2, 'linear'); % 'fillmissing'
figure;
plot(column2(1:2000));
fs = 40000;
l1 = length(column2);
fft_result = fft(column2-mean(column2))/l1; % <= CHANGED (Slightly)
fft_abs = abs(fft_result);
t = 0:1/fs:2000/fs;
freq = 0 : (1/t(end)) : fs/2 - (1/t(end));
figure;
plot(freq, fft_abs(1:length(freq)));
Do not use fillmissing on ‘data’ or much (possibly all) of the matrix disappears because of the third column.
.
Valeriya Kostyukova
2023-6-10
Star Strider
2023-6-10
My pleasure!
If my Answer helped you solve your problem, please Accept it!
.
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