MATLAB: FFT from time domain in excel

fftMATLAB

I am trying to get Frequency domain results from my Time domain analysis data regarding a floating offshore wind turbine responses.
I have learnt that I can use FFT in Matlab to perform this action. Can anybody suggest me how to do FFT and plots with excel file which has over 50000 lines of data?
I have attached one of the xlsx files that I need to FFT. Thank you.

Best Answer

There is not much to see in the plot: 
D1 = readmatrix('PlatformHeave.xlsx');
t = D1(:,1);                                                % Time Vector
Fs = 1/mean(diff(t));                                       % Sampling Frequency
Fn = Fs/2;                                                  % Nyquist Frequency
y = D1(:,2:end);                                            % Signal Matrix
ym = y - mean(y);                                           % Subtract Column Means From All Columns (Eliminates D-C Offset Effect)
L = numel(t);                                               % Signal Lengths
FTy = fft(y)/L;                                             % Fourier Transform (Scaled For Length)
Fv = linspace(0, 1, fix(L/2)+1)*Fn;                         % Frequency Vector
Iv = 1:numel(Fv);                                           % Index Vector
sep = ones(numel(Fv),1) * (1:size(FTy,2));                  % 'Separation  Matrix' — Plots Each Record In Its Column Locatioln
Fm = ones(numel(size(FTy,2)),1) * Fv;                       % Frequency Matrix
figure
plot3(Fm, sep, abs(FTy(Iv,:))*2)
grid on
xlabel('Frequency (Hz)')
ylabel('Record (Column #)')
zlabel('Amplitude')
set(gca, 'ZScale','log')
.
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