How to calculate the FFT period

The peak in an FFT magnitude result represents frequency, which is the reciprocal of the period. Multiply the frequency index reciprocal by the FFT window length to get the period result in the same units at the window length.

1. How do you find the period of a signal?
2. How many periods do I need for FFT?
3. What is the period of DFT?
4. How do you find the FFT of a signal?

How do you find the period of a signal?

You can use the formula ω=2πf where ω is the angular frequency (in rads), with the formula T=1f where T is the period of the signal (in seconds, s).

How many periods do I need for FFT?

Number of periods of signal required when doing an FFT: 1

yup.

What is the period of DFT?

the DFT spectrum is periodic with period N (which is expected, since the DTFT spectrum is periodic as well, but with period 2π). Example: DFT of a rectangular pulse: x(n) = 1, 0 ≤ n ≤ (N − 1), 0, otherwise.

How do you find the FFT of a signal?

y = fft(x); fs = 1/Ts; f = (0:length(y)-1)*fs/length(y); When you plot the magnitude of the signal as a function of frequency, the spikes in magnitude correspond to the signal's frequency components of 15 Hz and 20 Hz.