NAME

     tpstack  - module to do a forward tp or hyperbolic stack  of
     seismic data

SYNOPSIS

     tpstack [ -Nntap ] [ -Ootap ] [ -nsnstr  ]  [  -nenetr  ]  [
     -rsnrst  ]  [  -renred ] [ -vvel ] [ -tpstp1 ] [ -tpetp2 ] [
     -ntpnumtp ] [ -itnwt2 ] [ -otnwt1 ] [ -ffmax ] [ -Ftftaper ]
     [ -V ] [ -? ]

DESCRIPTION

     tpstack works on each record of input.  It  computes  static
     shifts for each trace distance based on the hyperbolic equa-
     tion described by  de Bazelaire, Geoph v. 53 p.143 1988  for
     each  time,  tp,  of  focussing  depth  and  then stacks the
     shifted traces.  The resultant stacked trace is then output.
     An  interesting feature of the output is that it is directly
     related to velocities and amounts  to  a  kind  of  velocity
     analysis for each trace...

     The output of tpstack can be piped into envelop to give  the
     envelope  traces which can then be displayed using oper with
     a color table suitable for displaying velocity  data.   This
     can  then  be picked.  The apparent velocities can be deter-
     mined by the relation  Va = vel * sqrt(tp/t0),  where t0  is
     the  2-way  travel  time of the plot and tp is the real hor-
     izontal scale of the plot.

     tpstack gets both its data and its parameters  from  command
     line  arguments.  These arguments specify the input, output,
     the velocity, the start and end focussing times, the  number
     of  times  to  output, the start and end traces, 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).

     -ns nstr
          Enter the start trace number.  The default is the first
          trace of the record.

     -ne netr
          Enter the end trace number. The  default  is  the  last
          trace of the record.

     -rs nrst
          Enter start record number.  Default value is the  first
          record.

     -re nred
          Enter end record number.  Default value is last record.

     -v vel
          Enter the shot medium velocity in m or ft/s.   This  is
          really  the  velocity  down  to the first reflector and
          scales all velocities determined from  the  tp  values.
          There is no default.

     -tps tp1
          Enter the start tp value  in  ms  (see  tpe  and  numtp
          below).  No default.

     -tpe tp2
          Enter the end tp value (ms).  No Default.

     -ntp numtp
          Enter the number of tp values between tp1 and tp2.  The
          increment is determined from this value and tp1 and tp2
          above and is written into the printout  file  and  into
          the trace headers on output.  The default is the number
          traces/record of the input data.

     -it nwt2
          Enter the number of traces to taper the inside  of  the
          spread.   This  is  sometimes  useful  for split spread
          input data.  A linear taper is  applied  to  nwt2/2  on
          either side of the gap from 1.0 down to 0.0 at the gap.
          Default is no taper.

     -ot nwt1
          Enter the number of traces to taper the outside of  the
          spread.   This  is  sometimes useful if the ends of the
          spread have high amplitude  events  which  might  caude
          endge effects.  Default is no taper.

     -f fmax
          Enter the maximum frequency (hz) to  use.   This  might
          help if the data are temporally resrtricted to low fre-
          quencies only.  Default is 1/2 nyquist.

     -Ft ftaper
          Enter the frequency (hz) range beyond fmax  over  which
          to  apply  a cosine spectral taper.  The effect of this
          is not known.  Default is no taper.

     -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.

AUTHOR

     Original code by R. Crider, ES&S;  this implementation by P.
     Gutowski, TRC

COPYRIGHT

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