| ifreq {seewave} | R Documentation |
This function returns the instantaneous frequency (and/or phase) of a time wave through the computation of the analytic signal (Hilbert transform).
ifreq(wave, f, channel = 1, phase = FALSE, threshold = NULL, plot = TRUE, xlab = "Time (s)", ylab = NULL, ylim = NULL, type = "l", ...)
wave |
an R object. |
f |
sampling frequency of |
channel |
channel of the R object, by default left channel (1). |
phase |
if |
threshold |
amplitude threshold for signal detection (in % ). |
plot |
logical, if |
xlab |
title of the x axis. |
ylab |
title of the y axis. |
ylim |
the range of y values. |
type |
if |
... |
other |
The instantaneous phase is the argument of the
analytic signal obtained throught the Hilbert transform.
The instantaneous phase is then unwrapped and derived against time to
get the instantaneous frequency.
There may be some edge effects at both start and end of the time wave.
If plot is FALSE, ifreq
returns a list of two components:
f |
a two-column matrix, the first column corresponding to time in seconds (x-axis) and the second column corresponding to instantaneous frequency in kHz (y-axis). |
p |
a two-column matrix, the first column corresponding to time in seconds (x-axis) and the second column corresponding to wrapped instantaneous phase in radians (y-axis). |
This function is based on the analytic signal obtained with the
Hilbert transform (see hilbert).
The function requires the package signal.
The matrix describing the instantaneous phase has one more row than the
one describing the instantaneous frequency.
Jerome Sueur sueur@mnhn.fr
Mbu Nyamsi, R. G., Aubin, T. & Bremond, J. C. 1994 On the extraction of some time dependent parameters of an acoustic signal by means of the analytic signal concept. Its application to animal sound study. Bioacoustics, 5: 187-203.
# generate a sound with sine and linear frequency modulations a<-synth(d=1, f=8000, cf=1500, fm=c(200,10,1000,0,0)) # plot on a single graphical device the instantaneous frequency and phase op<-par(mfrow=c(2,1)) ifreq(a,f=8000,main="Instantaneous frequency") ifreq(a,f=8000,phase=TRUE,main="Instantaneous phase") par(op)