ffilter {seewave} | 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, from = FALSE, to = FALSE, bandpass = TRUE, custom = NULL, wl = 512, wn = "hanning", output="matrix")
wave |
an R object. |
f |
sampling frequency of wave (in Hz). Does not need to be specified if embedded in wave . |
from |
start frequency (in Hz) where to apply the filter. |
to |
end frequency (in Hz) where to apply the filter. |
bandpass |
if TRUE a band-pass filter is applied between
from and to , if FALSE a band-stop filter is applied
between from and to (by default TRUE ). |
custom |
a vector describing the frequency response of a custom filter.
This can be manually generated or obtained with spec and meanspec .
wl is no more required. See examples. |
wl |
window length for the analysis (even number of points). |
wn |
window name, see ftwindow (by default "hanning" ). |
output |
character string, the class of the object to return, either
"matrix" , "Wave" , "Sample" ,
"audioSample" or "ts" . |
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
(fft
).
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 sueur@mnhn.fr
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(0,32),rep(1,32)),4) g<-fir(a,f=8000,custom=myfilter1) spectro(g,f=8000)