bimg - BSU program that cross correlates by relative offset cases (Fortran Version)
bimg [ -h | infile t1 t2 tlagmx jnear jfar ]
Basic Seismic Utilities (BSU) cross correlates traces with each other. Useful in cases of passive seismic sources. Output is sorted by relative offsets. The range of offsets is set by jnear and jfar (units of traces). The smallest offset is 1 trace separation, the maximum is the available near to far offset, but that will only be a single instance. Average group interval computed, assumed all traces are equally spaced. Acausal output is for waves propagating in one direction, causal section for waves propagating in the opposite direction (see file bimgxxxx.seg). The acausal and causal portions are combined without any weighting in second output file (see file BIMGxxxx.seg). Assumes all sources in line with geophones (no azimuthal corrections for apparent velocity). Likely use is traffic noise acquired along a road. Fortran-Language Version.
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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t1 |
Start time in seconds (float) of correlation gate. | ||
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t2 |
End time in seconds (float) of correlation gate. | ||
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tlagmx |
Maximum lag time (2 sides) of cross correlation. Example, if tlagmx=4.0 seconds, then 0 to 2.0 seconds is acausal side, 2.0 to 4.0 seconds is causal side of output. | ||
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jnear |
The minimum offset to be output in correlations. This will be 1 trace appart or more. The units are traces, an integer. For example, if we have a 48 trace record, the maximum amount of output will result if jnear = 1. | ||
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jfar |
The maximum offset to be output in correlations. This will less than or equal to the separation between the near and far trace. The units are traces, an integer. For example, ifwe have a 48 trace record, jfar = 48 is the largest value. While there will be only one instance of this separation, the number of output offsets are stacked traces where the stack decreases with offset. If N=number traces in record, then the maximum number of possible offsets are computed: |
N_offsets=(N-1) + (N-2) + (N-3) + . . . + (N-(N-1)). Thus for N=6, 15 traces will be output for jnear=1 and jfar=6. The near offset case will be 5 fold stack, and a single fold at the furthermost offset. A higher fold at the far offset output instance results from decreasing jfar.
NOTE:
If invoked with no options, will prompt user for input
parameters.
EXAMPLE:
bimg w001.seg 0. 20. 4. 1 24
File w001.seg is processed by bimg. Time gate is 0 to 20 seconds, cross correlation (2 sided) is 4 seconds. Output traces are cross corrlated result.
bimgxxxx.seg
Two sided correlation output. Named according to convention (first 4char bimg, the next 4char are the first 4char of the input file name, suffix .seg)
BIMGxxxx.seg
One sided corrlation, combined causal and acausal in a sum. Named according to convention (first 4char bimg, the next 4char are the first 4char of the input file name, suffix .seg)
standard output
produces a progress bar
bimgxxxx.lst
Echo check of input parameters in listing file.
bhelp(1), bcor(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]>