STFT语法解释.docx

spectrogram
Spectrogram using short-time Fourier transform
Syntax
S=spectrogram(x)
S=spectrogram(x,window)
S=spectrogram(x,window,noverlap)
S=spectrogram(x,window,noverlap,nfft)
S=spectrogram(x,window,noverlap,nfft,fs)
[S,F,T]=spectrogram(x,window,noverlap,F)
[S,F,T]=spectrogram(x,window,noverlap,F,fs)
[S,F,T,P]=spectrogram(...)
spectrogram(...)
Description
spectrogram, when used without any outputs, plots a spectrogram or, when used with an S output, returns the short-time Fourier transform of the input signal. To create a spectrogram from the returned short-time Fourier transform data, refer to the [S,F,T,P] syntax described below.
S = spectrogram(x) returns S, the short time Fourier transform of the input signal vector x. By default, x is divided into eight segments. If x cannot be divided exactly into eight segments, it is truncated. These default values are used.
window is a Hamming window of length nfft.
noverlap is the number of samples that each segment overlaps. The default value is the number producing 50% overlap between segments.
nfft is the FFT length and is the maximum of 256 or the next power of 2 greater than the length of each segment of x. Instead of nfft, you can specify a vector of frequencies, F. See below for more information.
fs is the sampling frequency, which defaults to normalized frequency.
Each column of S contains an estimate of