I am new at the use of FFT's and am trying to analyze a set of periodic data on a machine we now use that has some feed rate variation coming from the drive system. I wish to convert the peak j values to frequencies of the coefficients of interest. The help screan says:
Frequencies corresponding to coefficients Both fft and cfft return vectors whose elements are the complex amplitudes of the various frequencies in the original signal.
To recover the actual frequencies, you must know:
The sampling frequency of the original signal.
The number of samples in the original signal.
Given these parameters, the frequency associated with the jth element is given by:
where N is the number of data points in the analysis and f(s) is the frequency of sampling.
My question is what the units are for the corresponding C(k) values calculated in this manner. I am trying to understand the results I have obtained in terms of cycles of rotation of the drive system. Can anyone help?