NAME

     hodo  - 2-component analysis

SYNOPSIS

     hodo [ -Nntap ] [ -Fftap ] [ -Hhtap ] [ -Xxtap ] [ -Aatap  ]
     [ -sist ] [ -eiend ] [ -nsns ] [ -nene ] [ -rsirs ] [ -reire
     ] [ -flfl ] [ -fhfh ] [ -nfnf ] [ -lwlw ] [ -Sisrc ] [  -all
     ] [ -V ] [ -? ]

DESCRIPTION

     hodo analyzes various characteristics  of  2-component  data
     over  user  defined narrow band passes.  The outputs are all
     in 2-column xgraph format.  Currently the outputs  supported
     are  the  gaussian  bandpass filters, the particle motion or
     hodogram, the waveforms, and the agc gain curves.  The  goal
     is to acquire some understanding of the relationship between
     the two components as a function of frequency.

     hodo gets processing controls from the command line. Reason-
     able  defaults  are  set  up.   Input data is in the form of
     standard seismic records (whatever gather) of  trace  pairs,
     where  the traces of each pair is a component, e.g. first is
     vertical and the second is inline.

     This first version is pretty stripped down but  future  ver-
     sions  might output things like the rectilinearity function,
     correlation coefficient...


  Command line arguments
     -N ntap
          Enter the full path of the  file  containing  the  data
          set.  In none is given input defaults to a pipe.  Note:
          input data consists of 3-component  data  multiplxe  d,
          i.e.,  vertical,  radial, transverse, vertical, radial,
          traansverse, etc, for t he entire  gather.   This  data
          may be generated from separate data sets using  fBmergn
          with a -m flag.

     -F ftap
          Enter the output file  name  for  the  narrow  bandpass
          filters.   The default file name is filter.xg.  It con-
          sists of 2-column xgraph format.

     -H htap
          Enter the output file name  for  the  partical  motion.
          The  default  file  name is hodo.xg.  It consists of 2-
          column xgraph format.

     -X xtap
          Enter the output file  name  for  the  waveforms.   The
          default  file name is wave.xg.  It consists of 2-column
          xgraph format.

     -A atap
          Enter the output file name for  the  agc  gain  curves.
          The  default  file  name  is agc.xg.  It consists of 2-
          column xgraph format.

     -s ist
          (integer) Window start time The  start  and  end  times
          should  bracket the event of interest and should not be
          too long in order to avoid overwhelming xgraph.

     -e iend
          (integer) Window end time in ms.   The  start  and  end
          times  should  bracket the event of interest and should
          not be too long in order to avoid overwhelming xgraph.

     -ns ns
          First trace in record to process (default = 1)

     -ne ne
          Last trace in record to process (default = all)

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

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

     -fl, -fhfl,fh
          Minimum low cut and maximum high cut frequencies in  Hz
          for  gaussian narrow bandpass filters.  Default = 1.0Hz
          and 1/2 Nyquist, respectively.

     -nfnf
          Maximum number of frequency bands.   The  actual  value
          will be calculated internally and reported in the prin-
          tout file.  This is based on  the  contruction  of  the
          gaussian filters (e.g. their width, etc).  Default = 50

     -lw lw
          Length of agc window in ms  (default = 500 ms).

     -S isrc
          Source type determines on which component agc  computa-
          tion is done:

          1 = V
          2 = R
          0 = V+R (resultant): default


     -all If present, output all available xgraph files

     -V   If present give verbose printout

     -?   Query mode.  With this flag, hodo will give a  descrip-
          tion  of  the  command line arguments and stop the pro-
          gram.

DISCUSSION

     The program makes use of the gaussian  filter  comb  wherein
     adjacent  teeth  of  the conb are positioned such that their
     overall sum leads to a flat spectrum.

BUGS

     Be careful of the octave option  (negative  number  of  fre-
     quency  bands)  that  the upper band does not exceed nyquist
     (500/sample interval)

AUTHORS

     P. R. Gutowski, BP Research Center, 2000

COPYRIGHT

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