Fourier Transform of a CSV type data

[mcduff]

I believe/guess it is an optical spectrometer, like one that measure transmission or absorption. Thus measure intensity only, no phase information.

mcduff

[Alias110]

This is correct. Optical spectrometer only gives you amplitude vs frequency/wavelength. 

I have brought Matlab code here with required imported file ( spectrum data). 

Thank you for sharing your thoughts with me. 

Sincerely,

[PsyenceFact · Accepted solution]

Your MATLAB code uses a forward FFT on the real data in your CSV file so gives you a complex result.  You then plot the scaled absolute value of this result against time.  I haven't been able to look at your LabVIEW version of this as I'm (still) using 2015, but I can't see this being complicated.  Using FFT.vi should give you the same result and if you set the shift? input to TRUE, this will do the same as the MATLAB fftshift function and put the zero frequency at the centre of the data.  Something like this:

Still not what I'd call an inverse FFT though!

PsyenceFact

[mcduff]

+1 to what PsyenceFact said.

You need to read up on the fft.

mcduff

[Alias110]

Thanks for all of your helps