Evolutive MTM Spectrum
Time varying Auto-Regressive Spectrum (Gabor Transform) using MTM. This is a driver for MTMgabor.
doGABOR.MTM(Xamp, DT = 0.008, ppoint=95 , multi = 1, scale.def = 0, TWIN = 2, TSKIP = 0.2, PCTTAP = 0.05, PLOT=TRUE)
Xamp |
signal |
DT |
sample rate interval (s) |
ppoint |
percent confidence for F-test (default=95) |
multi |
Multiples of time window estimate |
scale.def |
scaling flag for plotting (0=raw, 1=log, 2=sqrt) |
TWIN |
time for window |
TSKIP |
time for skip |
PCTTAP |
percent of taper to apply to individual windows |
PLOT |
logical, TRUE=plot to device |
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.
list output of MTMgabor:
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) |
The main difference between this and other similar calls is the way the windows are determined.
Jonathan M. Lees<jonathan.lees@unc.edu>
Lees, J. M. and Park, J., 1995: Multiple-taper spectral analysis: A stand-alone C-subroutine, Computers \& Geology, 21(2), 199-236.
Percival, Donald B.,Walden, Andrew T. (1993):Spectral Analysis for Physical Applications,Cambridge University Press, Cambridge, 583p.
MTMgabor, evolfft, evolMTM, MTM.drive, GETARAIC, doGABOR.AR, DOsgram
data(KH) ### swig(KH) Xamp = KH$JSTR[[1]] Xamp = Xamp[57914:64914] EV = doGABOR.MTM(Xamp, DT = KH$dt[1], multi = 1, scale.def = 0, TWIN = 1, TSKIP = .1, PCTTAP = 0.05)
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