Description of the Merge Procedure.

When you run Merge, the following sequence is followed:

1. Determine the maximum absolute value on the reference phone vertical component (for the last even record). This is done by first running bscl on the last even record (brotL146.seg in the example) and then scanning the resulting listing for the amplitude. The bscl command is
   
    bscl brot$PRFX $evmax.seg 4 1 3 1>/dev/null 
   
   and the capture of the amplitude from the listing is done by the command
   
    AMP= gawk '/Peak Absolute Value/ {print $4}' bsclbrot.lst` 
2. A list of reduced file names is created with the file command. Thus, FILE=L001 L002 L003 . . L146 when the following command is executed:  
    
    FILE= find brot*seg | sed s/\.seg/”/g |sed s/brot/”/g`
3. The list in FILE is then directs a do loop which scales each brotL*.seg file first to unity maximum absolute amplitude on the reference vertical component, followed by a rescaling that makes all the files in the list end up having the same maximum absolute value on their respective vertical reference phone signals. This single new value is of course the AMP value captured in step (1) above.
4. The newly formed scaled versions all have been scaled to the same peak signal on their vertical reference, and this is dominated by the Near Field and Rayleigh waves. The goal is to null out the Rayleigh wave, and focus on the body waves down-hole. At this point, a sequence of bmrg runs are made to collect common receiver gathers. The files created are:
      a) rfv1.seg and rfv2.seg  [reference, Vertical for shot azimuths 270 and 90 degrees respectively]
      b) rft1.seg and rft2.seg  [reference, T-comp. for shot azimuths 270 and 90 degrees respectively]
      c) swt1.seg and swt2.seg  [down-hole, T-comp. for shot azimuths 270 and 90 degrees respectively]
      d) swv1.seg and swv2.seg  [down-hole, Vertical for shot azimuths 270 and 90 degrees respectively]
5. Enhancements without shaping filters are computed by subtracting the az270 files from the az90 files (SH-wave enhancement), or summing the az270 and az90 files (P-wave enhancement). The resulting output files are:
      a) twav.seg  [SH-wave enhanced, viewed on the T-component down-hole]
      b) pwav.seg  [P-wave enhanced, viewed on the Vertical component down-hole]
6. The shaping filter versions of enhanced P- and SH-waves is done by first running bshp on the reference phone traces, matching each reference to a target waveform, and then applying the filters on a second pass to the down-hole data. Thus, filter design is on the reference phone data, application is to both the reference phone (for QC) and to the down-hole (removes source fluctuations from down-hole data). The resulting file comparable to step (5) are:
      a) twave.seg  [SH-wave enhanced, viewed on the T-component down-hole]
      b) pwave.seg  [P-wave enhanced, viewed on the Vertical component down-hole]
   Note: The only difference in the names is the extra letter “e”.

In summary, the files twav.seg and pwav.seg are enhanced SH- and P-waves, without any shaping filters. The files twave.seg and pwave.seg have the additional Wiener Least Squares shaping based on observations of the reference phone.