genbzrt - BSU program to generate a bash script to run bzrt in a sliding time window
genbzrt [ USAGE: genbzrt filename tstart tend tstep tgate chV chH ipct hsw1 ]
Basic Seismic Utilities (BSU) bzrt uses Principal Component Analysis (PCA) to study the gross motion in the vertical plane recorded on a 3-C phone. This program generates a bash script which runs bzrt a number of times on a time series. Each execution of bzrt analyzes a sliding time window which progresses a vertical and a horizontal component. Plots of the motion and PCA analysis are done and output. All arguments must be provided on the command line (no prompting as in most BSU codes). Typing the command in a terminal will give the usage, and if less than all arguments are given on the command line, the code will abort and the usage message will be displayed. Program bzrt outputs an appendable file, bzrtpca.dat which captures a quadruplet of values for the time window. Plotting of this output file will reveal when a source passes near by the geophone (estimated from the amplitude of motion). At closest point where amplitude peaks, the PCA determined angle will indicate the major axis of the polarization ellipse. The angles are measured from the vertical axis and there is a 180 degree ambiguity. The default is to plot the column 3 angle and the column 4 amplitude. If the gross motion is vertical, then angles like 0 or -180 should be expected. If the gross motion is horizontally polarized, angles like -90 or +90 should be expected. Users should consider program hvsr for more detailed study of the Horizontal to Vertical spectral ratios. Much will depend on the wave type being analyzed, be it Rayleigh waves (in the context of modes present), or be it some other type of wave like a direct P- or S-wave. The code is in the C-language.
Options
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infile |
Input file name. | ||
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tstart |
Start time for the first time window (float, seconds). | ||
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tend |
End time for the sequence of windows (float, seconds). | ||
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tstep |
Time shift forward of sliding window (float, seconds). Windows can overlap or be separate. | ||
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tgate |
Length in time of the sliding window (float, seconds). If tstep < tgate, then overlap. | ||
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chV |
Channel number corresponding to V-component (int) | ||
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chH |
Channel number corresponding to H-component (int) | ||
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ipct |
Percent of peak motion modulus. To be included in PCA, sample amplitude must be > ipct. | ||
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hsw1 |
Switch to set H-component ID Examples: |
hsw1=2 If Horizontal component will be labeled R-component on plots.
hsw1=3 If Horizontal component will be labeled T-component on plots.
IMPORTANT: Make sure that hsw1 and chH are in agreement.
You are specifying directions that arrows on phone point, motion in that direction negative volts.
NOTE:
If invoked with no options, will display USAGE: message.
EXAMPLE:
genbzrt brsp0005.seg 0.00 20.0 .5 1.0 4 5 60 2
The V-component is channel 4, the H-component is channel 5, amplitudes larger than 60% of peak amplitude in window will be included in PCA. Windows start at 0.0 seconds and run to 20.0 seconds. Thus, the first window will be [0.0 to 1.0], the second window will overlap [0.5 to 1.5] . . . . and the last window will be [19.0 to 20.0] (since the gate is 1.0 and the move up is 0.5). The Postscript plots will be concatenated into a single file, bzrthodo.ps with the script then executing the ps2pdf program. If this program is not installed on your machine, you will want to delete that line in the script.
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gobzrt |
The bash script that runs bzrt commands. |
bzrtpca.dat
File with quadruplets (time, angle-1, angle-2, amplitude). File is appended so that multiple runs of genbzrt will build up a list of angles and normalized amplitude (see genbzrt code).
VPCA.gp
Gnuplot script to plot bzrtpca.dat data. The bash script will automatically run gnuplot and the output will be both X11 and Postscript file VPCA.gp.
bzrt.ps, bzrthodo.pdf
Postscript plots of particle motion
standard output
produces a progress bar
bhelp(1), bazi(1), genbazi(1), hvsr(1), bhod(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]>