evolfft {RSEIS} | R Documentation |
Spectrogram using simple fft (Gabor Transform)
evolfft(a, dt = 0, Nfft = 0, Ns = 0, Nov = 0, fl = 0, fh = 10)
a |
signal |
dt |
sample rate interval (s) |
Nfft |
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 |
This is a duplication of the spectrogram function in matlab which applies Welsh's Method.
List
sig |
input signal |
dt |
deltat |
wpars |
input parameters |
DSPEC |
spectrum image |
freqs |
output frequencies (y axis) |
tims |
output times (x-axis) |
Jonathan M. Lees<jonathan.lees.edu>
evolMTM, evolAR, MTM.drive
data(CE1) #### plot signals plot(CE1$x, CE1$y, type='l') ### set parameters Nfft=1024 ### fft length Ns=250 ### number of samples in a window Nov=240 ### number of samples of overlap per window fl=0 ### low frequency to return fh=1/(2*CE1$dt) ### high frequency to return ######## calculate the evolutive fft (Gabor Transform) EV = evolfft(CE1$y, dt =CE1$dt , Nfft = Nfft, Ns =Ns , Nov =Nov , fl =fl , fh = 25) ### plot image, but it does not look too interesting image(EV$DSPEC) ### plot Gabor transform with special function PE = plotevol(EV, log=0, fl=0.01, fh=100, col=rainbow(100), ygrid=FALSE, STAMP="", STYLE="fft")