NAME

     pomega  - module to obtain p-omega plot of data set

SYNOPSIS

     pomega [ -Nntap ] [ -rere ] [ -rsrs ] [ -nsns ] [ -nene ]  [
     -fminfmin  ] [ -fmaxfmax ] [ -cci ] [ -Cce ] [ -nraynray ] [
     -V ] [ -? ]

DESCRIPTION

     pomega takes a set of traces and performs a stacking  opera-
     tion to obtain a p-f plot. The method used is as follows. If
     there are N traces at distances  r(i)  and  if  the  Fourier
     Transform  of  each  trace is A(i)exp(phi(i)), then the func-
     tional

          F(f,p) = SUM abs[ phi(i) + omega*p*r(i) ],

     where the sum is from ]i = 1 to N.  This function will  have
     a maximum at the p-f phase velocity curves. The function can
     range between 0 and N. Its maximum value relative to  N  may
     be indicative of phase velocity error.

     pomega gets processing controls from the command line.  Rea-
     sonable defaults are set up. In addition, if no file name is
     given, the binary trace data are expected to be on the stan-
     dard  input.  The output on the standard output is the func-
     tion F(f,p)  (the frequency-ray parameter function) which is
     output as standard seismic traces and can be plotted as such
     (e.g. oper).

  Command line arguments
     -N ntap
          Enter the full path of the  file  continuing  the  data
          set.  If  not specified, input is expected on the stan-
          dard input. If standard input  is  not  specified,  and
          there  is  no  input,  e.g., program run in background,
          expect a  very  ungracious  crash.   (default  standard
          input)

     -O otap
          Enter the full path of the file continuing  the  output
          data set containing the F(f,p) function ( frequency-ray
          parameter function ).  (default standard output)

     -rs rs
          (integer) Give the first record for processing (default
          = 1)

     -re re
          (integer) Give the last record for processing  (default
          = last)

     -ns ns
          Define the starting trace for analysis (default = 1)

     -ne ne
          Define the last  trace  for  analysis  in  each  record
          (default = ns) The use of the ns and ne pair are useful
          to be able to skip dead traces or to select just a por-
          tion of the data set for analysis

     -V   Flag for verbose output on the  standard  output.  This
          lists  salient  trace header information as well as all
          command values used for processing,  the  default  ones
          given if not overridden.

     -fmin fmin
          Minimum frequency for contour plot.  Note  if  a  loga-
          rithmic scale is invoked, additional frequencies may be
          plotted since the logarithmic scale covers exactly  two
          cycles. (default = 1.0 Hz)

     -fmax -fmax
          Maximum frequency for contour plot.  In  no  case  will
          frequencies be above the Nyquist frequency.  (default =
          50.0 Hz)

     -c ci
          Initial phase velocity (m/sec  or  ft/sec)  (default  =
          1000)

     -C ce
          Final phase  velocity  (m/sec  or  ft/sec)  (default  =
          10000)

     -nray nray
          Maximum number of ray parameters to use spaced  between
          pi and pe (default = 20)

     -?   Query  mode.   With  this  flag,  pomega  will  give  a
          description  of the command line arguments and stop the
          program.

BUGS

     The hard limits in the program are 4096 point maximum  trace
     length  for  the  FFT. The FFT is computed for powers of two
     with zero fill where necessary.  There  is  no  tapering  or
     smoothing  at the endpoints of the trace. In addition, there
     is a hard limit of 300 traces, in a dimension  for  distance
     and trace fourier transform.

     Some checking is performed of the input  to  prevent  incon-
     sistencies, a little work would make it more fool proof.

     The program was written  expecting  units  of  ft  and  mil-
     liseconds  in  the  SIS  header.   Thus the plots will be in
     units of Hz and ft/sec.

SEE ALSO

     taupf and taupr

AUTHOR

     P. R. Gutowski, Amoco,  and  R.  B.  Herrmann,  Saint  Louis
     University, July 1985.

COPYRIGHT

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