R: Linear Frequency Shift

lfs {seewave}

R Documentation

Linear Frequency Shift

Description

This function linearly shifts all the frequency content of a time wave.

Usage

lfs(wave, f, channel = 1, shift, wl = 1024, ovlp = 75,
wn = "hanning", fftw = FALSE, output = "matrix")

Arguments

`wave`	an R object.
`f`	sampling frequency of `wave` (in Hz). Does not need to be specified if embedded in `wave`.
`channel`	channel of the R object, by default left channel (1).
`shift`	positive or negative frequency shift to apply (in Hz).
`wl`	window length for the analysis (even number of points, by default = 1024).
`ovlp`	overlap between successive FFT windows (in %, by default 75%).
`wn`	window name, see `ftwindow` (by default `"hanning"`).
`fftw`	if `TRUE` calls the function `FFT` of the library `fftw`. See Notes of the `spectro`.
`output`	character string, the class of the object to return, either `"matrix"`, `"Wave"`, `"Sample"`, `"audioSample"` or `"ts"`.

Details

A short-term Fourier transform is first applied to the signal (see spectro), then the frequency shift is applied and the new signal is eventually generated using the reverse of the Fourier Transform (istft).
There is therefore neither temporal modifications nor amplitude modifications.

Value

If plot is FALSE, a new wave is returned. The class of the returned object is set with the argument output.

Author(s)

Jerome Sueur sueur@mnhn.fr and Thierry Aubin thierry.aubin@u-psud.fr

References

Hopp, S. L., Owren, M. J. and Evans, C. S. (Eds) 1998. Animal acoustic communication. Springer, Berlin, Heidelberg.

Examples

data(orni)
a<-lfs(orni,f=22050,shift=1000)
spectro(a,f=22050)
# to be compared with the original signal
spectro(orni,f=22050)

[Package seewave version 2.1.6 Index]