BRPT

Pre-trigger refers to the time before a trigger signal is received. Engineering seismographs can retain data continuously sampled before the trigger signal. This program shifts the data and resets the delaytime header in the shot header section. The only argument is the input file. The delay time header value is shown in this sample bdump.lst of a file with a pre-trigger ( -10 ms pre-trigger).
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   Length =  2000 samples             |  Shot Elevation =      849.2
   Sample Interval =    0.00025 sec.  |  Shot Depth =        0.0
   Delay Time =  -10 msec.            |  Up Hole Time =     0 msec
   Low Cut Filter  =    0 Hz.         |  Shot X-COORD =    9963.19
   High Cut Filter = 1000 Hz.         |  Shot Y-COORD =   10022.41
   Line ID: 00X5                      |  Shot Date (year.moday) = 2001.0417
   Shot Orientation:                  |  Shot Time (hr:min)   = 10:32
   Azimuth=  0 Deg.  Vertical=180 Deg.|  Charge Size (grams)=     0
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 TRACE|SHOT| STATION | OFFSET|        RECEIVER          |VERT|1STBRK|K-GAIN|AZI|VER|
   #  |REC.|SHOT  REC|       |  ELEV.  X-COORD   Y-COORD|FOLD|(SEC.)| (dB) |   |   |