STFT computation

1. How is STFT calculated?
2. What is STFT used for?
3. What is the difference between FFT and STFT?
4. What is the magnitude of STFT?

How is STFT calculated?

In practice, the procedure for computing STFTs is to divide a longer time signal into shorter segments of equal length and then compute the Fourier transform separately on each shorter segment. This reveals the Fourier spectrum on each shorter segment.

What is STFT used for?

The short-time Fourier transform (STFT) is used to analyze how the frequency content of a nonstationary signal changes over time. The magnitude squared of the STFT is known as the spectrogram time-frequency representation of the signal.

What is the difference between FFT and STFT?

FFT has a resolution of 2048 lines, Blackman window, and 50% overlap and STFT also has Block size 2048, FFT size 16K, Blackman window used, and 50% overlap. As we can see, STFT performs better with the same block size (but more calculated lines). We improved frequency resolution for the same amount of scooped data.

What is the magnitude of STFT?

STFT magnitude, specified as a matrix. s must correspond to a single-channel, real-valued signal. Example: abs ( stft ( sin (pi/2*(0:255)),'FFTLength',128)) specifies the STFT magnitude of a sinusoid. Example: abs ( stft ( chirp (0:1/1e3:1,25,1,50))) specifies the STFT magnitude of a chirp sampled at 1 kHz.