What is the output of FFT in Matlab?

What is the output of FFT in Matlab?

Y = fft( X ) computes the discrete Fourier transform (DFT) of X using a fast Fourier transform (FFT) algorithm. If X is a vector, then fft(X) returns the Fourier transform of the vector. If X is a matrix, then fft(X) treats the columns of X as vectors and returns the Fourier transform of each column.

What is the frequency in FFT?

The frequency resolution is defined as Fs/N in FFT. Where Fs is sample frequency, N is number of data points used in the FFT. For example, if the sample frequency is 1000 Hz and the number of data points used by you in FFT is 1000. Then the frequency resolution is equal to 1000 Hz/1000 = 1 Hz.

How is the FFT used in signal analysis?

Computations Using the FFT The power spectrum shows power as the mean squared amplitude at each frequency line but includes no phase information. Because the power spectrum loses phase information, you may want to use the FFT to view both the frequency and the phase information of a signal.

What is the computational advantage of the FFT?

The computational advantage of the FFT comes from recognizing the periodic nature of the discrete Fourier transform. The FFT simply reuses the computations made in the half-length transforms and combines them through additions and the multiplication by e − (j 2 π k) N, which is not periodic over N 2, to rewrite the length-N DFT.

How are real times complex multiplications used in FFT?

For each frequency we chose, we must multiply each signal value by a complex number and add together the results. For a real-valued signal, each real-times-complex multiplication requires two real multiplications, meaning we have 2N multiplications to perform. To add the results together, we must keep the real and imaginary parts separate.

How is the amplitude of a FFT related to the phase?

The amplitude of the FFT is related to the number of points in the time-domain signal. Use the following equation to compute the amplitude and phase versus frequency from the FFT. where the arctangent function here returns values of phase between –π and +π, a full range of 2π radians.