NAME

     dghost - apply deghosting operation to seismic traces

SYNOPSIS

     dghost [ -Nntap ] [ -Ootap ] [ -nsns ] [ -nene ] [ -rsirs  ]
     [  -reire ] [ -hhzd ] [ -vvel ] [ -dxdx ] [ -tpct ] [ -V ] [
     -? ]

DESCRIPTION

     dghost  models  the  deghosting  operator  in  over  sampled
     omega-k  space, computes the operator, and applies it in the
     omega-k domain as a matrix multiply (convolution in the time
     domain).   Both the deghost operator and the data are cosine
     tapered in  space  and  time  (tapering  done  in  the  time
     domain).   One pass deals with either the source or receiver
     ghost depending on the type of sort.  In order to  get  both
     ghosts  the data will have to be resorted and passed through
     dghost again.

     dghost gets both its data and its  parameters  from  command
     line  arguments.  These arguments specify the input, output,
     the src/rcvr depth, the trace spacing, the taper  %,  hi-cut
     frequency, and src/rcvr velocity overrides.

  Command line arguments
     -Nntap
          Enter the input data set name or file immediately after
          typing  -N;  entering  nothing  specifies a 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.

     -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).

     -rs irs
          (integer) First record to process (default = 1)

     -re ire
          (integer) Last record to process (default = all)

     -dx dx
          Input trace spacing (ft,m) (default = none)

     -hh  Enter the source or receiver depth in ft or m  (default
          = none)


     -vvel
          Enter the water velocity (ft,m/s) ( default = none)

     -tpct
          Enter the % taper in time and space (default = 5%).  In
          frequency and wavenumber, the taper is also applied: in
          frequency it covers the low end as  well  as  the  high
          end,  i.e.  pct on each side.  Hence a pct taper cannot
          be greater than 50%.  In wavenumber the taper just cov-
          ers  the  highs  with  a notch at the water velocity to
          prevent artifacts having the water speed.

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

     -?   Enter this (or '-?' if you are running in  c-shell)  to
          get  online  help.   The  program  will terminate after
          printing this.

BUGS

     The filtering effects of the operator tends  to  enrich  the
     lower frequencies so it is advisable to do some sort of fre-
     quency compensation.  One amplitude friendly  method  is  as
     follows:

     timfreq -Nindata | ttothen -exp1 | freqtim | filt -fl5 -fh65
     -Ooutdata

     where indata is the de-ghosted data and outdata is the  fre-
     quency  compensated result.  The frequency boost is a linear
     ramp in frequency and  it  has  been  followed  by  a  broad
     bandpass  filter.  The results of this operation are usually
     rather impressive.

AUTHOR

     Original code by Tony Nekut, TRC (x4106);   usp  version  by
     Paul Gutowski

COPYRIGHT

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