ffilter | R Documentation |
This function filters out a selected frequency section of a time wave (low-pass, high-pass, low-stop, high-stop, bandpass or bandstop frequency filter).
ffilter(wave, f, channel = 1, from = NULL, to = NULL, bandpass = TRUE,
custom = NULL, wl = 1024, ovlp = 75, wn = "hanning", fftw = FALSE,
rescale=FALSE, listen=FALSE, output="matrix")
wave |
an R object. |
f |
sampling frequency of |
channel |
channel of the R object, by default left channel (1). |
from |
start frequency (in Hz) where to apply the filter. |
to |
end frequency (in Hz) where to apply the filter. |
bandpass |
if |
custom |
a vector describing the frequency response of a custom filter.
This can be manually generated or obtained with |
wl |
window length for the analysis (even number of points). |
ovlp |
overlap between successive FFT windows (in %). |
wn |
window name, see |
fftw |
if |
rescale |
a logical, if |
listen |
a logical, if |
output |
character string, the class of the object to return, either
|
A short-term Fourier transform is first applied to the signal
(see spectro
), then the frequency filter 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.
If plot
is FALSE
, a new wave is returned. The class
of the returned object is set with the argument output
.
Jerome Sueur
afilter
,lfs
,fir
,
preemphasis
, combfilter
, bwfilter
a<-noisew(f=8000,d=1)
# low-pass
b<-ffilter(a,f=8000,to=1500)
spectro(b,f=8000,wl=512)
# high-pass
c<-ffilter(a,f=8000,from=2500)
spectro(c,f=8000,wl=512)
# band-pass
d<-ffilter(a,f=8000,from=1000,to=2000)
spectro(d,f=8000,wl=512)
# band-stop
e<-ffilter(a,f=8000,from=1500,to=2500,bandpass=FALSE)
spectro(e,f=8000,wl=512)
# custom
myfilter1<-rep(c(rep(0,64),rep(1,64)),4)
g<-ffilter(a,f=8000,custom=myfilter1)
spectro(g,f=8000)
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