evolMTM {RSEIS}R Documentation

Evolutive Multi-taper Spectrum

Description

Time varying Multi-taper Spectrum (Gabor Transform)

Usage

evolMTM(a, dt = 0, numf = 1024, Ns = 0, Nov = 0, fl = 0, fh = 10)

Arguments

a Signal
dt Sample rate interval (s)
numf Number of points in fft
Ns Number of sample in sub-window
Nov Number of sample to overlap
fl low frequency to display
fh high frequency to display

Details

This is a spectrogram function similar to the Gabor Transform but uses the MTM method for spectrum estimation.

Value

List

sig input signal
dt deltat
wpars input parameters
DSPEC spectrum image
freqs output frequencies (y axis)
tims output times (x-axis)

Author(s)

Jonathan M. Lees<jonathan.lees@unc.edu>

References

Lees, J. M. and Park, J., 1995: Multiple-taper spectral analysis: A stand-alone C-subroutine, Computers & Geology, 21(2), 199-236.

See Also

evolfft, MTM.drive

Examples


data(KH)
###   PICK.GEN(KH)

Xamp = KH$JSTR[[1]]

dt = KH$dt[1]
plot(seq(from=0, length=length(Xamp), by=dt), Xamp, type='l')
##  limit the trace, somewhat
Xamp = Xamp[12670:22669]
plot(seq(from=0, length=length(Xamp), by=dt), Xamp, type='l')

Nfft=4096   ###  fft length
Ns=512      ###  number of samples in a window
Nov=480    ###  number of samples of overlap per window
fl=0        ###  low frequency to return
fh=12     ###  high frequency to return

EV = evolMTM(Xamp, dt = dt, numf = Nfft, Ns = Ns, Nov = Nov, fl = fl, fh
= fh)

PE = plotevol(EV, log=1, fl=0.01, fh=fh, col=rainbow(100), ygrid=FALSE,
STAMP="", STYLE="ar")

##   compare with:
## EVf = evolfft(Xamp, dt = dt, Nfft =Nfft , Ns =Ns , Nov =Nov , fl =fl, fh = fh)

##  PE = plotevol(EVf, log=1, fl=fl, fh=fh, col=rainbow(100), ygrid=FALSE,STAMP="", STYLE="fft")



[Package RSEIS version 2.1-4 Index]