BGAR

Computes an amplitude decay envelope over a user provided RANGE interval. The envelope is corrected for spherical divergence, converted to decibels, and a linear fit performed. The user may then apply the recommended gain correction, or over ride it with their own choice. The spherical divergence and exponential gain corrections are applied to the entire data set, (not just the interval of analysis). The data are not filtered before hand, so the decay measurements are a single result for the entire available bandwidth. If you want to measure inelastic decay as a function of frequency, then use program BAMP 8.2.6. This program simply provides a broad-band view of amplitude decay as sensed by the summed absolute value amplitude of each trace on a survey. A PostScript plot of the linear regression is output (requires PLPLOT package be installed)

   bgar  infile   rmin   rmax   dbu 
 
     infile   =  input file name
     rmin     =  min. range design gate  
     rmax     =  max. range design gate  
     dbu      =  gain correction to apply (dB/m)
NOTE: 
    No prompt for dbu until after gain assessment. 
    However, you may specify dbu on the command line 
    if you already have a value you wish to use.

Example, bgar c008.seg 6. 100. .03

Figure 77: BGAR: Broadband scale by spherical divergence and exponential decay. Range from 6 to 100 meters.

Figure 78: BGAR: Broadband scale by spherical divergence and exponential decay. Specified .03 dB/m for inelastic decay.