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

Arguments

wave

an R object.

sampling frequency of wave (in Hz). Does not need to be specified if embedded in wave.

plot

logical, if TRUE plots the dominant frequency along the time wave(by default TRUE).

interpol

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.

...

other plot graphical parameters.

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). NAs correspond either to pause periods (e. g. detected applying threshold) or sections of the time wave not crossing the zero line. To remove NAs with na.omit allows to get only instantaneous frequency values but discards information about pause sections.

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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