NAME

     psdm  - module to stretch and squeeze seismic data based  on
     a pick file model

SYNOPSIS

     psdm [ -Nntap ] [ -Ootap ] [ -Ppik ] [ -nsnstr ] [ -nenetr ]
     [  -rsnrst  ] [ -renred ] [ -fmaxhz ] [ -linear ] [ -cep ] [
     -R ] [ -V ] [ -? ]

DESCRIPTION

     psdm stretches and squeezes the data  based  upon  an  input
     model  in  xsd pick file format. This approach has been used
     to move primary/multiples into a desired position within  FK
     space  prior  to  application of dip filtering.  The program
     has an inverse option to return stretched-squeezed  data  to
     its original temporal location.

     psdm was designed originally to be used on stacked data sets
     to aid in multiple removal.  It has also been used on common
     offset sections to aid in multiple removal on prestack data.

     The input model must contain pairs of horizons.   The  first
     horizon  of  the  pair defines the surface to be moved while
     the second horizon defines the output datum to move the sur-
     face to.

     For each trace, the first and last samples remain fixed. All
     other data are stretched and squeezed according to the input
     model.  Because of this stretching and squeezing,  the  tem-
     poral  frequency of the data will change and could result in
     a significant amount of temporal aliasing in the  output  if
     the user is not careful.

     psdm retrieves its data and its parameters from command line
     arguments.   These  arguments specify the input, output, the
     pick file, sample, trace and record start and end, the  max-
     imum frequency of interest, the pick file sample units over-
     ride, forward-inverse flag, and verbose printout flag.

  Command line arguments
     -N ntap   [Default: stdin]
          Enter the input data set name 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 dif-
          ferent directory.   Example  -N/b/vsp/dummy  tells  the
          program to look for file 'dummy' in directory '/b/vsp'.

     -O otap   [Default: stdout]
          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).

     -P pickfile   [Default: none]
          Enter the input pick file name immediately after typing
          -P. The fully qualified path name is also required (see
          above).

     -ns nstr   [Default: first trace of record]
          Enter the start trace number.  This defines  the  first
          trace   to  be  processed.   All traces will be passed.
          Only the traces between -ns and -ne  will  actual  have
          psdm applied or removed.

     -ne netr   [Default: last trace of record]
          Enter the end trace  number.   This  defines  the  last
          trace   to  be  processed.   All traces will be passed.
          Only the traces between -ns and -ne  will  actual  have
          psdm applied or removed.

     -rs nrst   [Default: first record of dataset]
          Enter start  record  number.  This  defines  the  first
          record  to  be processed.  All records  will be passed.
          Only the records  between -rs and -re will actual  have
          psdm applied or removed.

     -re nred   [Default: last record of dataset]
          Enter end record number. This defines the  last  record
          to  be  processed.   All records  will be passed.  Only
          the records  between -rs and -re will actual have  psdm
          applied or removed.

     -fmax hz   [Default: option turned off]
          Enter the maximum frequency of interest  containted  in
          the dataset.  The routine will report to the print file
          any occurance of a squeeze that results  in  data  with
          frequencies  lower  than this being temporally aliased.
          This  parameter  is  not  required.   It  is  here  for
          tutorial purposes only.

     -R   Enter -R to remove the stretch-squeeze.  Omitting  this
          parameter will result in stretch/squeeze application.

     -linear
          Enter -linear to enable linear interpolation of  resul-
          tant  data  amplitudes.   Omitting  this parameter will
          result in the application of  cubic  spline  interpola-
          tion.

     -cep Enter -cep to inform psdm that the input dataset is  in
          fact  a prestak cdp sorted dataset corresponding to the
          stack that the pick control was obtained from.   It  is
          necessary  that  the  sequential  record  count of both
          datasets is  identical  AND  in  sync.   This  way  the
          stretch/ squeeze function that would normally have been
          applied to a trace of the stack is actually applied  to
          all  traces  of the CDP gather that make us that trace.
          This psdm'd CDP dataset can now be sorted to offset and
          fkstrip  or  a  filter of your choice can be applied in
          that space to perform the functional equivalent of  CEP
          Demult to your data.

     -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.

BUGS

     Unknown

SEE ALSO

     dipfk(1) fkstrip(1) psdm3d(1) fkshape(1) fkkstrip(1)

AUTHOR

     P.G.A.Garossino, Original code: D.A.Yanchak,  Original  sci-
     ence: S.L.Harris

COPYRIGHT

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