NAME

     timfreq  - forward fast fourier transform

SYNOPSIS

     timfreq [ -Nntap ] [ -Ootap ] [ -sist ] [ -eiend ] [ -nsnstr
     ]  [ -nenetr ] [ -rsnrst ] [ -renred ] [ -W ] [ -RI ] [ -P ]
     [ -M ] [ -V ] [ -? ]

DESCRIPTION

     timfreq implements the MathAdvantage forward  FFT,  converts
     the  transformed data into amplitude and phase (in degrees),
     and outputs the data in USP format.  The data are output  as
     trace pairs - amplitude and phase, or as single traces where
     the amplitude is in the top half of the trace (with  Nyquist
     at  sample  1)  and where the phase is in the bottom half of
     the trace (with Nyquist at the last sample).

     timfreq gets both its data and its parameters  from  command
     line  arguments.  These arguments specify the input, output,
     the design window, the start and  end  traces,  and  verbose
     printout, if desired.

DISCUSSION

     Once in the frequency domain the user can  apply  any  trace
     processing  code  to  these  traces recognizing that for the
     default mode of packing in each record the amplitude  values
     are  in traces 1, 3, ..., and the phase values are in traces
     2, 4, ...

     When the processing is completed freqtim will get  you  back
     to  real  time  domain traces with the only difference being
     the number of samples/trace will be a next power of 2.

  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).

     -s ist
          Enter the start time of the design window.  The default
          is  the  beginning  of  the  trace.  The filter will be
          applied to the whole trace, regardless of the -s and -e
          entries.

     -e iend
          Enter the end time of the design window.   The  default
          is the end of the trace.

     -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.

     -RI  Enter the command line argument '-RI'  to  output  real
          and  imaginaries  (default  is  to output amplitude and
          phase in degrees.

     -W   Enter the command line argument  '-W'  to  leave  phase
          unwrapped.  The default is to unwrap the phase.

     -P   Enter the command  line  argument  '-P'  to  cause  the
          amplitude  and phase or real and imaginary values to be
          packed into each output trace.  The  top  half  of  the
          trace will contain the amplitudes or reals with Nyquist
          starting at sample 1 and counting down  to  DC  at  the
          middle  sample.  The bottom half will contain the phase
          or imaginaries with DC at  the  middle  sample  plus  1
          counting  up  to Nyquist at the last sample.  With this
          option  there  will  be  the  same  number  of   output
          traces/rec  as the input.  If this option is to be used
          in the freqtim command line you must use it here.

     -M   Enter the command line  argument  '-M'  to  detect  the
          onset  mute  for  each  trace and store the time in the
          trace header slot VPick1 (where program mute  automati-
          cally stores its times).

     -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

     to operate on the output of this program you must  recognize
     that  the  traces are alternating amplitude and yphase pairs
     or that the amplitude and phase have been packed into a sin-
     gle trace.

SEE ALSO

     freqtim

AUTHOR

     Paul Gutowski, x3146, TRC

COPYRIGHT

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