NAME
rwspec - Spectral decomposition of a single or multiple
frequencies or periods via running window analysis.
SYNOPSIS
rwspec [ -Nntap ] [ -Ootap ] [ -sstart ] [ -eend ] [ -fmin-
min freq ] [ -fmaxmax freq ] [ -fintfreq increment ] [
-winwindow length ] [ -pminmin period ] [ -pmaxmax period ]
[ -pintperiod increment ] [ -tapercosine taper ] [ -nstrace
start ] [ -netrace end ] [ -rsrecord start ] [ -rerecord end
] [ -int ] [ -G ] [ -opbias ] [ -trbias ] [ -phase ] [ -V ]
[ -? ]
DESCRIPTION
rwspec Performs a spectral decomposition on seismic data for
a single or multiple user defined frequency or period (or
range) with the user defined sliding window which can have
a Gaussian or cosine taper on a range of samples defined by
start and end times of selected traces or ranges of traces
with a user specified value. Output is an sis format file
of the user defined spectral decomposition. The user may
define the output sample rate to reduce the size of the out-
put file and reduce the computation time. The program will
also scale to data to the correct limits (dynamic range) for
Landmark conversion.
rwspec gets both its data and its parameters from command
line arguments. These arguments specify the input, output,
the operator window, the percent of cosine taper, optional
landmark scaling, and verbose printout, if desired.
Command line arguments
-N ntap
Enter the input data set name or file immediately after
typing -N unless the input is from a pipe in which case
the -N entry must be omitted. This input file should
include the complete path name if the file resides in a
different directory. Example -N/b/vsp/dummy tells the
program to look for file 'dummy' in directory '/b/vsp'.
-O otap
Enter the output data set name or file immediately
after typing -O. This output file is not required when
piping the output to another process. The output data
set also requires the full path name (see above).
-s start time
Enter the global start time of the spectral decomposi-
tion. Default = trace start.
-e end time
Enter the global end time of the spectral
decomposition. Default = trace end.
-win window
Enter the window operator length. Default = 0.0.
-fmin min frequency
Enter the minimum frequency (hz) value of the desired
analysis.
-fmax max frequency
Enter the maximum frequency (hz) value of the desired
analysis.
-fint frequency interval
Enter the frequency interval for the analysis. Default
= 1.
-pmin min period
Enter the minimum period value of the desired
analysis.
-pmax max period
Enter the maximum period value of the desired
analysis.
-pint period interval
Enter the period interval for the analysis. Default =
1.
-taper percent taper
Enter the percent of cosine taper . Default = 0.0
-dto output sample rate
Enter the desired output sample rate . Default = input
sample rate. Confusion may arise as to the exact sam-
ple center time the program uses versus what you asked
for. This routine first calculates the closest sample
to your window start [-s above] and window end [-e
above]. It then converts your -dto[] entry to samples
and outputs centers going from start sample to end sam-
ple every dto samples. The number of output volume
equivalents is then related to how many times the above
loop executes prior to walking past your end sample. A
table is written to the printout file listing the out-
put volume window center samples and times that you can
consult to see what actually happened. It is polite to
give this routine -s, -e -dto parameters that land on
samples. Remember that in USP sample one is assumed to
be time zero. Also a -dto[] entry of less than your
sample interval is not valid. If you ask for such a
thing you will get the output at your input sample
interval. No interpolation is provided here.
-ns trace start
Enter the first record number for analysis Default =
1.0
-ne trace end
Enter the last trace number for analysis Default = end
of data
-rs recored start
Enter the first record number for analysis Default =
1.0
-re record end
Enter the last record number for analysis Default =
end of data
-int Enter the command line argument '-int' to flag for
scaling data for Landmark format conversion.
-G Enter the command line argument '-G' to get a Gaussian
taper.
-opbias
Enter the command line argument '-opbias' to remove the
operator bias during the decomposition calculation.
This, along with the trace bias removal above, used to
be the default in this routine [prior to June 28,
1999]. After much thought and consultation with
Gutowski and Vassiliou I can find no theoretical reason
for this operation. It can do nothing but harm to your
output thickness estimates. I would NOT use this
option and recommend AGAINST using it. I am leaving
the capability as an option merely for historical com-
pleteness. A user may need to turn this on to recreate
an old result. If you choose to try this option you
may well be faced with explaining what you think your
are doing.
-trbias
Enter the command line argument '-trbias' to remove
the trace bias prior to decomposition. This used to be
the default in this code as written by the original
authors. I am not sure what they were thinking as
assumptions of zero mean are really not valid for short
time series which are often the case with this applica-
tion. I believe the notion for this option came from
thinking about the FFT of a stationary time series
where zero mean is an assumption that makes sense. It
is a dangerous option to invoke here however, espe-
cially if you are after thickness estimates in the
presence of thinning units. I am leaving this capabil-
ity as an option in the program purely for historical
reasons. Also a user may want to recreate an old
result and may need this turned on for that purpose.
Please be very careful with your analysis and give this
a lot of theoretical thought if you choose to use this
option [Garossino].
-phase
Enter the command line argument '-phase' calculate
phase.
-V Enter the command line argument '-V' to get additional
printout.
-? Enter the command line argument '-?', -h or -help to
get online help. The program terminates after the help
screen is printed.
DISCUSSION:
For an excellent primer on this process point your web
browser to
http://eptgweb/~usp/TechTransfer/OnlineTraining/Spec_Tutorial/SpecDoc.html
BUGS
unknown
AUTHOR
James M. Gridley and Greg Partyka, 27 July 1995. Complete
rewrite [Paul G.A. Garossino June, 1999] to correct fre-
quency referencing errors as well as make trace and operator
bias removal an option rather than the default. Many com-
puter science gitches were fixed and the code was made com-
patible with program spec so that the same results can be
had by either routine.
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
Man(1) output converted with
man2html