hvsr - BSU compute and plot Horizontal to Vertical spectral ratio
hvsr [ -h | infile | chV | chH | tmin | tmax | mpts | idata | wht ]
Basic Seismic Utilities (BSU) computes spectral ratio Horizontal/Vertical component from multi-component seismic recordings. One can choose to either input the seismic signals or autocorrelations of the signals (idata). Using autocorrelations is provided if one wishes to stack recordings from a number of geophones in one analysis. It is assumed that the source may be passive, no trigger signal available. To compute autocorrelations external to this program, use program bxcr specifying the same file for both infile arguments (the code can also do cross-correlations). The results from bxcr runs for different geophones can be stacked using program bsum as many times as needed for each file. If all the autocorrelations are in the same file, then bstk would be used. This program, hvsr, will need an estimate of the order of the process. This order is the number of samples of the autocorrelation to include. The resulting spectra will be Yule-Walker All Pole. One may choose to run the program first with a large order and inspect the output autocorrelations to decide on the order. The smaller the order, the smoother the spectral estimates will appear. Output plot files are in GNUPLOT format. These can be edited to change the range of frequencies to be plotted (the default is out to the Nyquist). See the "set xrange[0 : Nyquist ] parameter to edit, reducing the upper limit. Spectra are computed from the Z-transform evaluated on the unit circle at a sampling of 1/imax Hz. Default compile set imax = 4 (0.25Hz freq. increment). This can be changed in the code if desired and recompiled. Fortran 90.
Options
|
-h |
Online help giving details on command line arguments | ||
|
infile |
Input file name | ||
|
chV |
Channel with vertical component signal. | ||
|
chH |
Channel with horizontal component signal. | ||
|
tmin |
Start time of the window for autocorrelation unless autocorrelations are input. | ||
|
tmax |
End time of the window for autocorrelation unless autocorrelations are input. | ||
|
mpts |
Number of sample lags to include (one sided autocorrelation regardless of input). Note that the bxcr code will compute a two sided autocorrelation, but this is reduced to just one sided inside the hvsr code if idata = 1. | ||
|
idata |
Switch to specify which type of data are being input to hvsr. |
idata = 0 time series recorded
by geophone
idata = 1 autocorrelations
|
wht |
Whitening parameter. This is the percent of the zero lag autocorrelation to add to the zero lag autocorrelation. The result will bias the spectral amplitudes greater than zero. There is a risk that a ratio with zero in the denominator will blow up. Suggest a value like .01 for this parameter. |
NOTE:
If invoked with no options, will prompt user for input
parameters.
EXAMPLE:
hvsr 0000.seg 1 2 0 .25 28 0 .01
Input file 0000.seg is processed using the recorded time series for the H and V components. The correlation will be taken for signals between 0 and 0.25 seconds. The number of autocorrelation lags will be 28. The whitening is .01% of the zero lag value.
hvsrauto.ps and hvsrauto.gp
Postscript and gnuplot files for showing autocorrelations
hvsrspec.ps and hvsrspec.gp
Postscript and gnuplot files for showing the spectral amplitudes of the vertical and horizontal spectra.
hvsratio.ps and hvsratio.gp
Postscript and gnuplot files for showing the H/V spectral ratio as a function of frquency.
hvsrauto.dat
Text file with columns: lag, vertical, and horizontal autocorrelations (normalized).
hvsrXXXX.dat
Text file with columns: Frequency, Vertical, Horizontal, and H/V results. The XXXX in the name will depend on the input file name. For the example above, hvsr0000.dat would be the name.
hvsrXXXX.lst
Listing file for hvsr. The characters, XXXX, will be the first 4 char of the input file name.
bhelp(1), bxcr(1) bsum(1) bstk(1) xcor1(1) eureka(1)
No known bugs.
Copyright © 2021 by Paul Michaels
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
P. Michaels, PE. <[email protected]>