MATLAB: How to use FFT in matlab using imported data in time domain excel file

fft

i have some polymers characterized by transmission terahertz time domain spectroscopy (THz-TDS).

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Import the data into MATLAB using xlsread()

Your data will be a Nx2 matrix in MATLAB with the first column the time data and the second column the data you want to Fourier transform.

So for example:

[X,TXT,RAW] = xlsread('yourfile.xls');
xdft = fft(X(:,2));

Related Solutions

MATLAB: Use FFT in matlab and get phase plot

Here are the frequencies associated with the output from FFT:

Nt =              % Number of time samples
Fs =              % sample frequency (= 1/dt)
df = Fs/Nt;       % frequency increment
Nyq = Fs/2;       % Nyquist frequency
if mod(Nt,2) == 0 % Nt is even
   freq = ifftshift(-Nyq : df : Nyq-df);
else              % Nt is odd
   freq = ifftshift([sort(-1*(df:df:Nyq)) (0:df:Nyq)]);
end

Then you can just do a xlim on the plot to zoom in on a specific frequency range.

MATLAB: FFT of vibration data

     Fs = 800; % sampling rate of 1000 Hz
     t = 0:1/Fs:1-1/Fs;
     x = ad2;
     xdft = fft(x);
     xdft = xdft(1:length(x)/2+1);
     DF = Fs/length(x); % frequency increment
     freqvec = 0:DF:Fs/2;
     plot(freqvec,abs(xdft))

I hope this can work

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Related Solutions

MATLAB: Use FFT in matlab and get phase plot

MATLAB: FFT of vibration data

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