NAME
wesh - is for wavelet estimation and shaping on common-
source records.
SYNOPSIS
wesh [ -Nntap ] [ -Ootap ] [ -Ccardin ] [ -? ]
DESCRIPTION
wesh uses a highly-averaged autocorrelation function com-
puted both across a common-source input record, as well as
separate time windows for each trace, to determine the
source wavelet in each record. An operator is then computed
and applied to each record to shape the determined wavelet
to a desired (Butterworth) wavelet.
The data is exponentially-scaled to make the (possibly
slightly mixed-phase) computed source wavelet into a
minimum-phase wavelet. Next, an average autocorrelation
function is computed by summing normalized autocorrelations
computed over successive overlapping windows down each trace
and over selected traces of the record. Next, we compute a
minimum phase wavelet from the average autocorrelation using
the Wiener-Levinson algorithm and synthetic division.
Inverse exponential scaling then produces the mixed-phase
source wavelet sought for each common-source record.
Finally, we shape each wavelet to a Butterworth wavelet
(zero-phase or minimum-phase).
NOTE: The input dataset should contain common-source (or
common-receiver) records. The input dataset is limited to
1024 traces/record and 6000 samples/trace.
Command line arguments
-N ntap
Enter the full path name of the file containing the
input data set. If not specified, input is expected to
be on the standard input (a pipe into wesh). If no
input file is given, and there is no standard input,
the program will abend.
-O otap
Enter the full path name for the output file to receive
the output data. If no output file is specified, the
program will write the output data to the standard out-
put (a pipe out of wesh).
-C cardin
File from which processing parameters necessary for
executing wesh are specified in card image format. An
error message will be issued if cardin does not exist.
Enter the full path name for the input file containing
the card images. This parameter is not required if
parameters are input by command line arguments. How-
ever, if this file is specified, and a parameter is
also specified in a command line argument, the command
line argument takes precedence.
-lwv lengwv
Enter the wavelet length is ms. Blank or zero defaults
to 200.
-scl rscal
Enter the exponential scaling factor. Default is .98.
Limits are zero and 1.0; program will abend if rscal is
not within these limits.
-lfr nflow
Enter the lower cutoff frequency in HZ of output
Butterworth wavelet. Default is zero. Imposed limits
are zero or nyquist.
-ldb nrlow
Enter the cutoff rate in dB/oct at the lower cutoff
frequency of the output Butterworth wavelet. Default
is 24.
-hfr nfhigh
Enter the upper cutoff frequency in HZ of the output
Butterworth wavelet. Default is zero. Imposed limits
are zero or nyquist.
-hdb nrhigh
Enter the cutoff rate in dB/oct at the upper cutoff
frequency of the output Butterworth wavelet. Default
is 24.
-st1 ntime1
Enter the start time in ms (at near range limit) of
first data window for computing autocorrelations.
Default is 0.
-lwn ntleng
Enter the window length in ms of data windows for com-
puting autocorrelations. Default is 1000.
-sti nstinc
Enter the start time increment in ms of data windows
for computing autocorrelations. Default is 200.
-nw nwndws
Enter the number of successive data windows for comput-
ing autocorrelations. Default is 3.
-vel velwnd
Enter the velocity, in ft/ms or m/ms, to adjust the
start time of the design window. Default is 99.99.
-nr nrang1
Enter the near range limit in feet for computing auto-
correlations. Default is 0.
-fr nrang2
Enter the far range limit in feet for computing auto-
correlations. Default is 999999.
-Z Phase of output Butterworth wavelet; no -Z gives
minimum phase(default); using -Z gives zero phase
wavelet.
When a card image file is specified, the parameter
cards required for wesh are:
Card Image: data column entries
Column Variable
*******This card is REQUIRED*******
Only one 1WESH card allowed per execution.
******* MUST be the first parameter card input.******
1-5 1WESH (required)
6-10 Wavelet length in ms
blank or 0 = 200
22-25 Exponential scaling factor. Decimal may be entered.
blank or 0 = 0.98
33-35 Lower cutoff frequency in Hz of output Butterworth wavelet
blank = 0
37-39 Cutoff rate in dB/octave at lower cutoff frequency of
output Butterworth wavelet
blank or 0 = 24
41-43 Upper cutoff frequency in Hz of output Butterworth wavelet
blank = 0
45-47 Cutoff rate in dB/octave at upper cutoff frequency of
output Butterworth wavelet
blank or 0 = 24
Column Variable
*******This card is REQUIRED*******
Only one 2WESH card allowed per execution.
******* MUST follow 1WESH ******
1-5 2WESH (required)
7-11 Start time, in ms, of first design window for
computing autocorrelations.
blank = 0
12-15 Design window length, in ms
blank or 0 = 1000
16-19 Increment between successive design windows
blank or 0 = 200
20 Number of windows for computing autocorrelations.
blank or 0 = 3
21-24 Velocity to adjust start time of design windows
(ft/ms or m/ms). Decimal may be entered.
default = 99.99
26-31 Minimum range (ft or m) for computing autocorrelations
blank = 0
32-37 Maximum range (ft or m) for computing autocorrelations
blank = 999999
NOTE: Minimum range MUST be less than Maximum range.
45 Flag for phase of estimated wavelet
blank or 0 = minimum-phase
1 = zero-phase
-? Query mode. With this flag, wesh will
send a description of the command line arguments to the
standard error output and stop.
If operating under the Berkeley shell (csh), the -? must be quoted
with single quotes, i.e., '-?'.
BUGS
No trap for running program without an input file and noth-
ing in the standard input.
A command line option letter and its corresponding argument
may not be separated by whitespace.
AUTHOR
Marilyn Miller (May, 1993)
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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