With these considerations in mind, the theoretical average FFT noise floor is 6.02n+1.76 dB+10 log[(3×M)/(π×ENBW)], where M is the number of data points in the FFT, ENBW is the equivalent noise ...

A Fast Fourier Transform (FFT) plot is generated by collecting a large number of conversion samples from the output of the A/D converter in a periodic fashion that is receiving an AC input signal.

Power spectral density is simply the Fourier transform of the signal. When we have a discrete case, as in Figure 2 , the PSD can be calculated by using the fast Fourier transform (FFT) algorithm.