MTMgabor: Evolutive MTM Spectrum

In RSEIS: Seismic Time Series Analysis Tools

Evolutive MTM Spectrum

Description

Time varying Auto-Regressive Spectrum (Gabor Transform) using MTM

Usage

MTMgabor(a, dt = 0, ppoint=95 , numf = 1024, Ns = 0, Nov = 0, fl = 0, fh = 10)

Arguments

a	signal
dt	sample rate interval (s)
ppoint	percent confidence for F-test (default=95)
numf	Number of frequencies
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 (multi-taper method) for spectrum estimation. This is a non-interactive version of MTM.drive.

Value

List

sig	input signal
dt	deltat
numfreqs	Number of frequencies output
wpars	input parameters list(Nfft=numfreqs, Ns=Ns, Nov=Nov, fl=fl, fh=fh)
DSPEC	spectrum image
HIMAT	matrix with high values of F-test at 90 percent confidence
DOFMAT	Matrix image of degrees of freedom
FVMAT	Matrix image of F-test values
kdof	test degrees of freedom=2*nwin-2
ppoint	percentage point for confidence bounds
freqs	output frequencies (y axis)
tims	output times (x-axis)

Author(s)

Jonathan M. Lees<[e-mail]>

References

Percival and Walden;

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

Percival, Donald B.,Walden, Andrew T. (1993):Spectral Analysis for Physical Applications,Cambridge University Press, Cambridge, 583p.

See Also

evolfft, evolMTM, MTM.drive, GETARAIC, doGABOR.AR, DOsgram, doGABOR.MTM

Examples

data(KH)
###   swig(KH)

Xamp <- KH$JSTR[[1]]
Nfft <- 1024   ###  fft length
Ns <- 512      ###  number of samples in a window
Nov <- 480    ###  number of samples of overlap per window
fl <- 0        ###  low frequency to return
fh <- 12     ###  high frequency to return
 dt  <-  KH$dt[1]

####  shorten the signal here, just for speed on the example:
sig = Xamp[37501:75001]

EV <-   MTMgabor(sig, 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")

RSEIS documentation built on Sept. 13, 2024, 1:09 a.m.