genbhod - BSU program generates bash scripts to determine down-hole tool orientation by PCA HORIZONTAL IMPACT SOURCES
genbhod [ no options ]
Basic Seismic Utilities (BSU) program generates 4 bash script files which can be run to determine 3-C geophone orientations based on the large particle motion. Two of the scripts are for a surface, reference geophone, and two are for the down-hole geophone. The Principal Component Analysis (PCA) is actually done by the program, bhod. There are many assumptions made in this code! The code is hard wired for the specific data collection method of the author.
Users are advised to consult the comments in the source code, genbhod.f, and the BSU documentation (BSU User’s Manual).
EXAMPLE:
genbhod
Enter 1char_ALPHA PREFIX
w
enter FIRST FILE NUBER (<=3digits) for which the source polarization is 270 deg.
1
enter LAST FILE NUMBER (<=3digits) for which source polarization is 270 deg.
165
enter UP/DOWN SWITCH
+1
enter azimuth of bowspring (R-component)
45
The above exchange between the program (italics) and user specifies that files w001.seg through w165.seg (odd numbers only) were shot with the source blow from East to West (270 deg azimuth), and files w002.seg through w166.seg (even numbers only) were shot with the opposite source effort (90 deg azimuth). The SH-wave enhancement will subtract scaled versions of odd file numbers from even file numbers (w002.seg - w001.seg for example which would be renamed h002001.seg). The scaling will be done on the vertical component (to better null out the Rayleigh and P-waves) before the subtraction. The hxxxyyy.seg files will undergo PCA by program,bhod, and tool azimuth will resolve R-component toward 45 degrees azimuth. The user is responsible for changing the permissions on the bash scripts to execute.
In general, one will only run gobhod and gobrunbhod (the down- hole tool scripts). However, the reference tool versions provide insight into how the source polarization changes with time into the survey (since the reference phone is fixed in orientation). Once down-hole tool orientation has been determined (file bhod.lst from bhod), one will want to insert the horizontal component orientations into headers (program btor). This will be followed by a rotation into alignment with the source polarization with program brot.
DOWN-HOLE TOOL
|
gobhod |
Scales and subtracts alternating down-hole signals, moving the result to hxxxyyy.seg files. Run this file first in directory where 6 channel field records reside. |
gorunbhod
Applies PCA analysis to horizontal traces (2 and 3). This bash script is run second in the directory where the hxxxyyy.seg files reside. Basically, this script executes bhod for each hxxxyyy.seg file.
REFERENCE-PHONE
gobhodR
Scales and subtracts alternating reference signals, moving the result to hxxxyyy.seg files. Run this file first in directory where 6 channel field records reside.
gorunbhodR
Applies PCA analysis to horizontal traces (5 and 6). This bash script is run second in the directory where the hxxxyyy.seg files reside. Basically, this script executes bhod for each hxxxyyy.seg file.
bhelp(1), genbhodV(1), bhod(1), bsum(1), bscl(1), btor(1), brot(1)
Michaels, P., 2001, "Use of Principal Component Analysis to Determine Down-Hole Tool Orientation and Enhance SH-Waves", Journ. Environmental and Engineering Geophysics, Vol. 6, No. 4, December, p175-183.
No known bugs.
Copyright © 2017 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. <pm@cgiss.boisestate.edu>