zc: Instantaneous frequency of a time wave by zero-crossing

Description

This function measures the period of a full oscillating cycle.

Usage

zc(wave, f, channel = 1,  plot = TRUE, interpol = 1, threshold = NULL,
xlab = "Time (s)", ylab = "Frequency (kHz)", ylim = c(0, f/2000),
warning = TRUE, ...)

Value

If plot is FALSE, zc returns a two-column matrix, the first column corresponding to time in seconds (x-axis) and the second column corresponding to the instantaneous frequency of the time wave in kHz (y-axis).

‘NA’s correspond either to pause periods (e. g. detected applying

threshold) or sections of the time wave not crossing the zero line. To remove ‘NA’s with na.omit allows to get only instantaneous frequency values but discards information about pause sections.

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).
plot: logical, if TRUE plots the dominant frequency along the time wave(by default TRUE).
interpol: a numeric vector of length 1, interpolation factor.
threshold: amplitude threshold for signal detection (in % ).
xlab: title of the x axis.
ylab: title of the y axis.
ylim: the range of y values.
warning: a logial to specify if warning message should be displayed or not when interpol is > 100.
...: other plot graphical parameters.

Author

Jerome Sueur sueur@mnhn.fr, Caroline Simonis and Thierry Aubin

Details

If plot is FALSE, zc returns a vector of numeric data with the instantaneous frequency.

References

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

Examples

Run this code

data(pellucens)
pellu1 <- cutw(pellucens,f=22050,from=0,to=1,plot=FALSE)
# without interpolation
zc(pellu1,f=22050,threshold=5,pch=20)
# with interpolation
zc(pellu1,f=22050,threshold=5,interpol=20,pch=20)
# a way to plot with a line and to filter low frequencies
pellu2 <- zc(pellu1,f=22050,threshold=5,interpol=20,plot=FALSE)
pellu3 <- na.omit(pellu2[,2])
pellu4 <- pellu3[pellu3>3]
plot(x=seq(0,nrow(pellu1)/22050,length.out=length(pellu4)),
    y=pellu4,type="l",xlab="Time(s)",ylab="Frequency(kHz)")

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