NAME

     rhfoc  - x-t elastic offset seismograms in SIS/USP format

SYNOPSIS

     rhfoc [ -fntap ] [ -Ootap ] [ -aalp ] [ -lntau ] [ -flfl ] [
     -fhfh  ]  [ -t ] [ -s ] [ -o ] [ -p ] [ -A ] [ -V ] [ -D ] [
     -P ] [ -? ]

DESCRIPTION

     This program takes the F(f,r) (or  F(f,p)  in  the  case  of
     plane waves from hspecp) output of hspec9, convolves it with
     the source time response by frequency domain multiplication,
     inverse Fourier transforms and multiplies by exp(alpha t) to
     yield the desired F(t,r) (or  F(t,p))  in  SIS  sun  format.
     Choice of acceleration, velocity, or displacement phones are
     available.  format.

     This is final downstream program to generate elastic  offset
     seismograms  from  a  horizontally  stratified  earth  model
     defined by layer thickness, p &  s-wave  velocities,  densi-
     ties, and p & s "Q".

  Command line arguments
     -f file
          Name of the output file of the program rhwvinta.

     -O otap
          Name of the output file (SIS format) to be  written  to
          disk.  If absent then a pie out is assumed.

     Pulse types

     -d -t -o -p
          Source time function to  use.  Default  is  "-d"  delta
          function  filtered  back to a default 80% nyquist, "-t"
          indicates a symmetric triangular pulse, "-p"  indicates
          a  symmetric  parabolic  pulse,  and  "-o" indicates an
          Ohnaka pulse. Unless you are an earthquake  expert  the
          delta function is recommended.

     -fl fl
          Enter the low cut 6db point of the internal butterworth
          filter.  Default = 5Hz

     -fh fh
          Enter the high cut 6db point of  the  internal  butter-
          worth filter.  Default = 80% nyquist

     -s shft
          Enter the shift of the output trace in  ms.  The  shift
          will  be  rounded to nearest sample before application.
          Positive values cause the trace to be shifted  upwards.
          Default = 0.

     -l L L indicates the pulse duration multiplier. The triangu-
          lar  pulse has a total duration of L*dt seconds and the
          parabolic pulse has a total duration of 4*L*dt seconds.
          The  default value is L = 8, indicated when the -l flag
          is not present.

     -a alp
          This controls the corner frequency of the Ohnaka pulse.
          The  Ohnaka  spectrum  has an omega-squared corner fre-
          quency at omega = alp.

     Type of receiver

     -V   Indicates velocity phone is used to record the data

     -D   Indicates an displacement phone is used to  record  the
          data

     -A   Indicates an accelerometer is used to record the data

     -P   Indicates output is to be plane waves with ray  parame-
          ter written into the trace headers.  Otherwise the out-
          put will be X-T with ranges written into the trace dis-
          tance headers.

     Since  the  output  of  the  hspec9  and   hspecp   programs
     correspond  to  a Dirac delta source time functions, the use
     of these pulses yields velocity time histories.  The  pulses
     have  unit  area.  If  the  input specifies distances in km,
     velocities in km/sec and densities, then the output of rhfoc
     corresponds  to a source with seismic moment = 1.0E+20 dyne-
     cm.

INPUT

     All control parameters are defined in the command line.

OUTPUT

     Output is in standard SIS  format  (ieee  floats  and  ascii
     text) suitable for further processing.

SEE ALSO

     dspec8, hspec9, hspecp

SAMPLE OUTPUT

     The following command line example assumes the spectrum file
     swe0010  was already generated by hspecX. The output of this
     program was then used as input of the program filt. The con-
     trolling command was

          rhfoc -fswe0010 -d -V | davc | filt -Oodata -fl5 -fh55

AUTHOR

     R. B. Herrmann, Saint Louis University, 1983

COPYRIGHT

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