NAME

     getamp  - get amplitudes from seismic traces

SYNOPSIS

     getamp [ -Nntap ] [  -Pptap  ]  [  -titm  ]  [  -wiwin  ]  [
     -HWheaderwordfR  ]  [  -nsnstr  ]  [ -nenetr ] [ -rsnrst ] [
     -renred ] [ -max ] [ -min ] [ -maa ] [ -head ] [ -nb ] [  -x
     ] [ -E ] [ -V ] [ -? ]

      >  [disk file]

DESCRIPTION

     getamp retrieves amplitudes at a user  specified  time  from
     traces  in  a  seismic  data  set  or  finds the maximum (or
     minimum or maximum absolute) amplitude from  a  window  cen-
     tered on the specified time.  Currently a single time may be
     given so that the event of interest must be flattened  using
     constant  refraction velocity moveout (vred), normal moveout
     (anmo, dipnmo, tvdnmo), or flattened using an oper pick file
     (from  the seismic plot) and programs flatten to write flat-
     tening times into the trace headers, piped into program rest
     to  apply the flattening times.  The user may also specify a
     XSD pickfile with a picked event (only one  per  trace)  and
     use  that  as  the  center of the time window.  The user may
     also read a time from any user defined header word  for  the
     center of the time window.

     Note: the amplitude information along with  the  record  and
     trace  number  will  be  written  to standard out (it can be
     redirected to a disk file name).

     getamp gets both its data and its  parameters  from  command
     line  arguments.  These arguments specify the input, output,
     the amplitude time, 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'.

     -P ptap
          Enter the XSD pickfile name with the  amplitude  values
          (default = no pick file).

     -t time
          Enter the time of the tracking window in ms  (must  set
          -T flag below.  The window is centered about this trace
          time, itm and the maximum (or minimum) amplitude within
          this  window  is  found.   A  message is written if the
          start or end of the window  is  picked  -  chances  are
          there's been a bust in the picking

     -w iwin
          Enter the length of the tracking window in ms (must set
          -T  flag below.  The window is centered about the above
          trace time, itm and the maximum (or minimum)  amplitude
          within  this  window is found.  A message is written if
          the start or end of the window is picked - chances  are
          there's  been  a bust in the picking.  This may also be
          used with pick files and the header word option.

     -HW hdrwrd
          Enter the trace  header  word  mnemonic  to  be  either
          listed  in the output along with the amplitude and time
          (default = none) or define the trace header  word  with
          the   window   time.    The   output  format  will  be:
          i6,4x,i6,9x,e15.5,5x,i5 (i.e. fields 1-6, 11-16, 26-40,
          and  46-50)  in the order record #, trace #, amplitude,
          time(ms)  or  the  case  of  adding  a   header   word,
          i6,4x,i6,9x,e15.5, 5x,i5,5x,i5 (i.e. fields 1-6, 11-16,
          26-40, 46-50 and 56-60) in the order record #, trace #,
          amplitude, time(ms), trace heaer word.

     Program xgraph may be used to plot the output  (as  in  this
     example):

          getamp -Nindata -t1000 -w200 -h119 -P -T > amps

          cut -c11-16,26-40 < amps | xgraph

     where we have run getamp in the tracking mode with  a  200ms
     window  centered  on 1000ms looking for the maximum positive
     value.  We then plot the signed trace distance vs the ampli-
     tude.

     An alternative to using cut is awk. In the above example  if
     we  wanted  to  plot  the  second and third columns we could
     enter

     awk '{print $1,$2}' < amps | xgraph

     -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.

     -nb  Enter the command line argument '-nb' to  not  separate
          records  in the output file with a blank line, i.e. all
          entries in the output  file  will  be  one  line  after
          another.

     -max Enter the command line argument '-max' to extract  max-
          imum positive amplitudes.

     -min Enter the  command  line  argument  '-min'  to  extract
          minimum negative amplitudes.

     -maa Enter the command line argument '-maa' to extract  max-
          imum absolute amplitudes.

     -x   Enter the command  line  argument  '-x'  to  output  in
          xgraph format.

     -E   Enter the command line argument '-E'  to  output  exact
          time  values  associated with the extracted amplitudes.
          This will work with every option.

     -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.

BUGS

     unknown, please inform the USP Team if any are found.

SEE ALSO

     vred, anmo, flatten, rest

AUTHOR

     P. R. Gutowski, James M. Gridley (August 1995 version)

COPYRIGHT

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