What are the units of my data after an FFT?

Your raw data is in mv vs 1/time thus after FFT the ordinate still has units of mv and the abscissa units of time.

1. What units does FFT return?
2. What are the outputs of FFT?
3. What does FFT do to data?
4. Does Fourier transform change units?

What units does FFT return?

If you take the Fourier transform of x(t) to get X(jw) , then the units of X(jw) are C*sec or C/Hz (according to the Fourier transform integral). If you use (abs(X(jw)))^2 , then the units are C^2*sec^2=C^2*sec/Hz .

What are the outputs of FFT?

These frequencies actually represent the frequencies of the two sine waves which generated the signal. The output of the Fourier transform is nothing more than a frequency domain view of the original time domain signal.

What does FFT do to data?

It transforms time-domain data into the frequency domain by taking apart a signal into sine and cosine waves. In a complex signal, the FFT helps the engineer to determine the frequencies that are being excited and the amplitude at each frequency.

Does Fourier transform change units?

So the Fourier transform of a time series does not have units of frequency. It actually has units of inverse-frequency added on, so that when we multiply it by a frequency, we get the same units back that we started with. For example, if f is measuring volts, F has units of volts-seconds.