bazi - BSU program to solve for PCA on R- and T- components of 3-C surface phone
bazi [ -h | infile | chR | chT | ipct | tsw1 | tmin | tmax ]
Basic Seismic Utilities (BSU) uses Principal Component Analysis (PCA) to determine direction to a seismic source based on hodogram motion in horizontal plane as recorded on a 3-C phone. Intended to sense Rayleigh waves, the user is responsible for understanding the source and likely type of wave sensed. One can set a threshold for analysis (ipct), and this can help favor the likely hood of surface waves in the recording, assuming the geophone is on the surface of the ground. A postscript file is created to plot the samples above the threshold and the vectors resolved to point either toward or away from the source RELATIVE to the R-component. There is a 180 degree ambiguity. One must also provide an angle indicating the direction of the T-component relative to the R-component (positive clockwise). File baziPCA.lst, contains quadruplets specifying the time at the center of the window, the two angles resolved by PCA, and the amplitude of the signal (a large amplitude implies a near source). Program genbazi is a sister program that can generate a bash script to scroll down a time series recording when examining the direction and amplitude of a source in passive data. Code is in Fortran 90.
Options
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-h |
Online help giving details on command line arguments | ||
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infile |
Input file name. | ||
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chR |
Channel number corresponding to R-component | ||
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chT |
Channel number corresponding to T-component | ||
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ipct |
Percent of peak motion modulus. To be included in PCA, sample amplitude must be > ipct. | ||
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tsw1 |
Switch to set T-component relative to R-component. Examples: |
tsw1=+90 If R=East, T=South
tsw1=-90 If R=East, T=North
You are specifying directions that arrows on phone point, motion in that direction negative volts.
|
tmin |
Start time of analysis window in seconds. |
|||
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tmax |
End time of analysis window in seconds. |
NOTE:
If invoked with no options, will prompt user for input
parameters.
EXAMPLE:
bazi 0000.seg 2 3 75 +90. 1.0 1.5
The R-component is channel 2, the T-component is channel 3, amplitudes larger than 75% of peak amplitude in window will be included in PCA. Window starts at 1.0 seconds and ends at 1.5 seconds.
bazi.ps
Postscript plot of PCA.
bazipca.lst
File with quadruplets (time, azimuth-1, azimuth-2, amplitude). File is appended so that multiple runs of bazi will build up a list of azimuths and amplitude (see genbazi code).
baziXXXX.lst
This lists the PCA analysis details. Naming convention for example above, XXXX=0000, (ie. bazi0000.lst). Includes Echo check of input parameters in listing file.
standard output
produces a progress bar
bhelp(1), genbazi(1), bzrt(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]>