Q {seewave}R Documentation

Resonance quality factor of a frequency spectrum

Description

This function estimates the frequency pureness of a time wave by returning the resonant quality factor Q at a specific dB level.

Usage

Q(spec, f = NULL, level = -3, plot = TRUE, colval = "red",
cexval = 1, fontval = 1, flab = "Frequency (kHz)",
alab = "Relative amplitude (dB)", type = "l", ...)

Arguments

spec a data set resulting of a spectral analysis obtained with spec, or meanspec (in dB). This can be either a two-column matrix (col1 = frequency, col2 = amplitude) or a vector (amplitude).
f sampling frequency of the wave used to obtain spec (in Hz). Not necessary if spec is a two columns matrix obtained with spec or meanspec.
level frequency bandwidth set by an amplitude value relative to spectrum (in dB).
plot logical, if TRUE returns the spectrum with Q plotted (by default TRUE).
colval colour of plotting Q.
cexval character size of plotting Q.
fontval font of plotting Q.
flab title of the frequency axis.
alab title of the ampltiude axis.
type if plot is TRUE, type of plot that should be drawn. See plot for details (by default "l" for lines).
... other plot graphical parameters.

Details

A high Q value indicates a highly resonant system.

Value

Q is returned as a single numeric data.

Note

This function is based on fft.

Author(s)

Jerome Sueur sueur@mnhn.fr

See Also

spec, meanspec, corspec, fft.

Examples

# bird song
data(tico)
t<-spec(tico,f=22050,at=1.1,plot=FALSE,dB=TRUE)
op<-par(mfrow=c(2,1),las=1)
Q(t,type="l")
Q(t,type="l",xlim=c(3.8,4.2),ylim=c(-60,0))
title("zoom in")
par(op)
# cricket, changing the dB level
data(pellucens)
p<-spec(pellucens,f=11025,at=0.5,plot=FALSE,dB=TRUE)
op<-par(mfrow=c(3,1))
Q(p,type="l",xlim=c(1.8,2.6),ylim=c(-70,0))
title("level = - 3 (default value)",col.main="red")
Q(p,type="l",level=-6,
    xlim=c(1.8,2.6),ylim=c(-70,0),colval="blue")
title("level = - 6",col.main="blue")
Q(p,type="l",level=-9,
    xlim=c(1.8,2.6),ylim=c(-70,0),colval="green")
title("level = - 9",col.main="green")
par(op)

[Package seewave version 1.5.0 Index]