NAME

     gasp - apply general amplitude scaling to trace data

SYNOPSIS

     gasp [ -Nntap ] [ -Ootap ] [ -Cctap ] [ -coef ] [  -t0startw
     ]  [ -tmaxstopw  ] [ -vwinvel ] [ -hw1startw ] [ -hw2stopw ]
     [ -hwsscalar ] [ -sscale factor ] [ -rsirs ] [  -reire  ]  [
     -rec ] [ -job ] [ -max ] [ -med ] [ -R ] [ -V ] [ -? ]

DESCRIPTION

     gasp scales data based on a design window.  Scaling consists
     of  computing a scale factor and applying this the the input
     data.  The scale factor can be computed in 3 ways:

     1. trace constant

     2. record constant

     3. job constant

     and using 3 modes:

     1. maximum absolute amplitude

     2. average absolute amplitude (based on live traces  &  live
     samples)

     3. median amplitude

     When using record constant scaling a  coefficients  file  is
     created  so  that  the record constant scaling may be backed
     off at some future point in the processing flow.  Should the
     command  line  entry   -coef  be  present  the  routine will
     attempt to apply the gain coefficients found in the attached
     coefficients file.

     Regardless of the scaling method chosen the scalar used  may
     be  recorded  in  the  trace  header using the -hws[] option
     below.  If used the scaling may be removed at any  point  in
     the  future by simply running gasp with the -R option below.
     There is no need to flag the removal with -job, -rec etc  as
     the  scalar  in  the  trace header will be used for removal.
     There is no facility at present to then reapply this  scalar
     though  such an option could be added if needed.  Be certain
     to use a floating point header entry such as Horz08 to store
     the scalar.

     gasp gets both its data and its parameters from command line
     arguments.   These  arguments specify the input, output, the
     amplitude scale factor , and the operator length in ms.


     Note: you can pipe into gasp only for trace or  record  con-
     stant  scaling.   An  attempt  to pipe in using job constant
     scaling will cause an abort.  For job constant  scaling  you
     must have the data resident on disk.

  Command line arguments
     -Nntap
          Enter the input data set name or file immediately after
          typing  -N,  entering  nothing implies stdin pipe. This
          input put 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  'vsp'  stored  on the 'b' disk.
          Note: if job constant scaling is  required  or  records
          are  very  large (>8000 traces) an attempt to pipe into
          this process will give an error

     -Ootap
          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).

     -Cctap
          Enter the coefficients data set name  or  file  immedi-
          ately  after typing -C.  This file contains the coeffi-
          cients applied when using the -rec option.  If accessed
          in  concert  with the -R option below then a previously
          applied gain will be removed from the data.  This  file
          may  be viewed using xgraph which may be an interesting
          way of examining record to record coupling  variations.
          (def = GaspCoef)

     -coef
          Enter -coef to apply  the  gain  coefficients  from  an
          attached coefficients file.  This option is only possi-
          ble when using the record constant option.

     -t0 startw
          Start time of window used to compute scale factor  (def
          = 0 ms)

     -tmax stopw
          End time of window (def = last sample)

     -vwinvel
          Adjust t0 using trace distances and  this  velocity  in
          ft,m/sec (def=999999)

     -hw1startw
          Mnemonic of trace header entry containing the  analysis
          window  start time in milliseconds.  If not included on
          command line this option will not be used.

     -hw2stopw
          Mnemonic of trace header entry containing the  analysis
          window  end  time  in milliseconds.  If not included on
          command line this option will not be used.

     -hwsscalar
          Mnemonic of trace header entry to contain, or  contain-
          ing  the  scalar used for the trace.  The default is to
          not load anything to the trace header.  If you use this
          option  be certain to use a floating point header entry
          such as Horz01 thru Horz08.  There is a  check  in  the
          program to warn you if you have messed up here.

     -sscale factor
          Enter the scale factor that specifies  what  percentage
          of  2047  you  want  the  average  absolute  amplitude.
          (default = 15%)

     -job, -rec
          Enter -job for job constant scaling, or -rec for record
          constant  scaling,  or nothing for trace constant scal-
          ing.

     -max Enter -max to use maximum absolute amplitude for  scale
          factor or nothing to use

     -rsirs
          Enter start record to process.

     -reire
          Enter end record to process.

     -med Enter -med to use median amplitude  for  scale  factor.
          Be  very cautious when using this option for trace con-
          stant scaling - bad  traces  can  get  gained  substan-
          tially.

     -R   Enter the command line argument '-R' to remove the gain
          previously applied.  This option is available only with
          -rec and requires the input  of  a  valid  coefficients
          file (see -C above).

     -V   Enter the command line argument '-V' to get  additional
          printout.

     -?   Enter the command line  argument  '-?'  to  get  online
          help.   The program terminates after the help screen is
          printed.

COPYRIGHT

     copyright 2001, Amoco Production Company
               All Rights Reserved
          an affiliate of BP America Inc.