ShortTimeFT: Short Time Fourier Transformation

In Mthrun/TSAT: Time Series Analysis Tools (TSAT)

Short Time Fourier Transformation

Description

Short Time Fourier Transformation

Usage

ShortTimeFT(Datavec, LenWindow,

TypeWindow, GaussianApha=1,

PlotIt=TRUE,Window, ...)

Arguments

Datavec	[1:n], numerical vector of data
LenWindow	Width of the window defined as a length which is typical a small fraction of data
TypeWindow	"hanning", "gaussian" or "specific" can be selected
GaussianApha	standard deviation of gaussian windwo
PlotIt	plots the spectrogram
Window	if specific provide window in convention of specgram
...	see stft for hanning or see specgram

Details

Gaussian Window results in Gabor Transformation

I would be better if data length n is dividable with 2 (e.g. 1024), otherwise approximations are made internally.

"specific" requires a vector which is the result of a window function of signal

Value

List with

Amplitude	Amplitude[1:m:1k] numerical matrix
Spectrogram	stft or specgram

Note

Transformations of Tics to frequencies in Hz are not provided so far..

Author(s)

Michael C. Thrun

References

Lectures of MCT

See Also

stft,

specgram

Examples

t0=seq(from=0.001,
to=2.5,
length.out = 256) 

y=c(cos(2*pi*1.0*t0),
    cos(2*pi*2.5*t0),
    cos(2*pi*5.0*t0),
    cos(2*pi*7.5*t0))

#10sec of ticks of time
t=seq(from=0.001,
to=10,
length.out = 256*4) 


plot(t,y,type='l',
ylab='Amplitude',xlab='Time in sec')

x=ShortTimeFT(y,WindowLen = 8,PlotIt = T)

Mthrun/TSAT documentation built on Feb. 5, 2024, 11:15 p.m.