NAME

     samps  - module to compute amplitude/phase spectra

SYNOPSIS

     samps [ -Nntap ] [ -Ootap ] [ -rsirs ] [ -reire ] [ -tsits ]
     [  -teite  ]  [ -siwst ] [ -eiwed ] [ -tipt ] [ -f1freq1 ] [
     -f2freq2 ] [ -fifinc ] [ -P ] [ -XY ] [ -V ] [ -? ]

DESCRIPTION

     samps computes amplitude or phase spectra for the input data
     as  per  the  input  parameters.   The  conventional Fourier
     transform is used (rather than the Fast  Fourier  Transform)
     so  that  the  frequency sample increment can be arbitrarily
     specified. The output, either amplitude or phase is smoothed
     using  the  Hamming-Tukey  method.  Output  data consists of
     amplitude or phase spectra that are  either  in  normal  sis
     format  or  in  the  form of x-y pairs and can be plotted by
     means of oper or x-y plotting programs such as xgraph  (plot
     x-y  pairs in X-windows).  The sample interval in the output
     data line header is set to milli-Hz and hence output  scales
     can be read as Hertz.

     samps gets both its data and  its  parameters  from  command
     line  arguments.  These arguments specify the input, output,
     the start and end records and traces, start  and  end  times
     for windows, frequency end points, frequency increment ,win-
     dow  tapering, and verbose printout, if desired.

  Command line arguments
     -N ntap
          Enter the input data set name or file immediately after
          typing  -N.   If piping in this command line entry will
          be omitted.  The 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).

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

     -re ire
          Enter the end record number.   Default  value  is  last
          record.


     -ts its
          Enter start trace number.  Default is  first  trace  of
          record.

     -te ite
          Enter end trace number.  Default value is last trace of
          record.

     -s iwst
          Enter start  time  of  window  for  harmonic  analysis.
          Default is the start of the trace.

     -e iwed
          Enter end of window for harmonic analysis.  Default  is
          end of trace.

     -t ipt
          Enter percent taper to apply to window.  Default is  no
          taper.

     -dB  If amplitude output in decibels is desired,  enter  the
          maximum decibel deflection.

     -f1 freq1
          Enter  beginning  frequency  for   harmonic   analysis.
          Default is 0 Hz.

     -f2 freq2
          Enter ending frequency for harmonic analysis.   Default
          is Nyquist frequency.

     -fi finc
          Enter frequency increment in Hz.  Default is 1./(window
          length in sec.).

     -P   Enter the command line argument '-P' to  output  phase.
          The analysis window center is the phase reference.

     -XY  Enter the command line argument  '-XY'  to  output  x-y
          pairs  (freq  and  either amplitude or phase) to stdout
          which can either be redirected to a file  or  piped  to
          xgraph (if you are using x-windows).

     -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.

EXAMPLE 1:

     Export a slab of seismic amplitude data  called  'rwflt.3dv'
     from  a  landmark  proje  ct  called  'baltim'  bounding the
     'eocene' horizon for use in routine samps.
      Bring the resulting frequency traces to Landmark as a "3dv"
     file which can be u sed for subsequent frequency slices.

     #!/bin/sh -e
     lm3dvtosis -project baltim -input rwflt.3dv |
     lm3dhrztosis -project baltim -h1 eocene |
     stratslab -uhHORZ01 -uw-50 -lw+50 -tmax 100 -tdatum 50 -ttaper 10 |
     samps -f270 -fi1 -Oout.samps
     utop -Nout.samps -dt1 |
     sistolm3dv -project baltim -output nsfr01.3dv

REFERENCES:

BUGS

     No bugs known at present.

SEE ALSO

     flatten, rest, lm3dhrztosis

COPYRIGHT

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