BEXT

Traces can be extracted by either shot or receiver name in the BSEGY headers. Alternatively, field record number can also be used. This is useful when more than one shot record is in a larger file. The command line arguments are:
 bext  infile   extsw    value
 
     infile   =  input file name
     extsw    = extraction switch (1 char)
             s= shot name  
             r= receiver name  
             f= field record number 
     value    = shot or rec name (4 char) 
                       or 
                field record number (int) 
 
  WARNING: leading blanks are important   
  (enclose 4 char string in quotes if on command line)
 
   Use bdump program to find names of shots or receivers

For example, consider extracting the traces with receiver label 30 in a file with two shots.
bext merged.seg r " 030"
A partial dump of the headers for merged.seg is:

   30 |   8|8001  030| 148.53| 1000.50   9938.79   9800.50| 1|0.0514|   40 |  0|  0|
   78 |   9|9048  030|  85.15| 1000.50   9938.79   9800.50| 1|0.0386|   40 |  0|  0|
This shows that traces 30 and 78 are at receiver name “ 030” and have the same (x,y,z) coordinates.

Figure 69: BEXT: Extracted traces from receiver location “ 030”. In the merged file (A) red arrows show receiver “ 030” and these are replotted in (B). Note the receiver name is 4 characters, “blank,zero,three,zero”.
\includegraphics[scale=.9]{Figurebext.pdf}