# FFT of vibration data, Help me please.

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Phakapol Tungboontina am 11 Mai 2022
Dear friends
I have vibration data from the device, I need to convert it into Freq Domain (Magnitude vs Freq). I've tried several times and still stuck, I can't import that data into the formula/function. I've attached an excel file I got from the device. maybe you can download and see the excel files for complete information. Could you guys help me, what function/formula should I write? and how to find the max point in the plot?
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Star Strider am 11 Mai 2022
Try this —
T1 = 717×6 table
hours Current Voltage axis x axis y axis z _____ _______ _______ ______ ______ ______ 1 0.182 228.8 -0.14 -0.25 0.84 2 0.181 228.8 -0.1 -0.22 0.84 3 0.182 229 0.07 -0.06 0.86 4 0.182 228.9 0.04 -0.12 0.86 5 0.181 228.7 0.02 -0.08 0.85 6 0.182 228.9 0.15 -0.01 0.86 7 0.182 229.1 0.02 -0.1 0.85 8 0.181 228.8 0.16 0.04 0.86 9 0.181 228.9 0.02 -0.12 0.84 10 0.181 228.6 0.25 0.14 0.89 11 0.181 228.7 0.19 0.1 0.87 12 0.181 228.9 -0.17 -0.23 0.84 13 0.181 228.8 0.17 0.09 0.88 14 0.182 229.1 0.3 0.17 0.89 15 0.182 229.2 0.29 0.12 0.87 16 0.182 229.5 0.12 -0.01 0.86
VN = T1.Properties.VariableNames
VN = 1×6 cell array
{'hours'} {'Current'} {'Voltage'} {'axis x'} {'axis y'} {'axis z'}
L = size(T1,1);
% QQ1 = nnz(diff(T1{:,1}) ~= 1)
Ts = T1.hours(2) - T1.hours(1); % Sampling Interval
Fs = 1/Ts; % Sampling Frequency
Fn = Fs/2; % Nyquist Frequency
NFFT = 2^nextpow2(L); % For Efficiency
FT_T1 = fft(T1{:,2:end} - mean(T1{:,2:end}), NFFT)/L; % Fourier Transform (Mean Subtracted To Show Other Peaks More Clearly)
Fv = linspace(0, 1, NFFT/2+1)*Fn; % Frequency Vector
Iv = 1:numel(Fv); % Index Vector
figure
plot(Fv, abs(FT_T1(Iv,:))*2)
grid
xlabel('Frequency (hr^{-1})')
ylabel('Amplitude')
legend(VN{2:end}, 'Location','best')
NrSp = size(FT_T1,2);
NrSp = 5
figure
for k = 1:NrSp
subplot(NrSp,1,k)
plot(Fv, abs(FT_T1(Iv,k))*2)
grid
ylabel('Amplitude')
title(VN(k+1))
end
xlabel('Frequency (hr^{-1})')
.
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Star Strider am 11 Mai 2022
As always, my pleasure!
Phakapol Tungboontina am 11 Mai 2022
Can you help me another question that I post in topic How to conversion of Acceleration FFT to Velocity?

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