Transform | FFT

Applies the Fast Fourier Transform (FFT ) algorithm to all time domain measurements in a Data Block to transform each of them into its frequency spectrum (DFT ).

The FFT is a loss-less (also called one-to-one & onto) transformation from one domain (time or frequency) to the other
An original time waveform can always be recovered by applying the Inverse FFT to its DFT.

Prime Number FFT

ME'scope uses a prime number FFT, which does not required that the Block Size (number of samples) be equal to a power of 2.

Data Block Before FFT.

Data Block After FFT.

One Sided Versus Two Sided FFT

All of the energy in a time domain signal is spread of all frequencies, including both positive & negative frequencies in its DFT.  The FFT always calculates a Two Sided FFT, where half of a signal is represented by positive frequencies, and half by negative frequencies in its spectrum.  Therefore, a One Sided FFT yields spectrum values that are twice the values of a Two Sided FFT.  The frequency spectrum of a real valued time waveform is symmetric about zero frequency (DC), so only the positive frequency half of the spectrum is displayed.

The amplitude & power values of a DFT calculated with a Two Sided FFT are only half of the values of the its corresponding time waveform
The amplitude & power values of a DFT calculated with a One Sided FFT are the same values as its corresponding time waveform.