seewave (version 1.1)

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 = FALSE,
xlab = "Time (s)", ylab = "Frequency (kHz)", ylim = c(0, f/2000),...)

Arguments

wave

data describing a time wave.

f

sampling frequency of 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 functions returns a vector of numeric data. Values corresponds to the instantaneous frequency of the time wave. NAs correspond either to pause periods (e. g. detected applying threshold or sections of the time wave not corrsing 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

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)
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)")