BSHP

Wiener least squares shaping filter design and application to standardize an embeded wavelet. When used in a down-hole survey, it can be used to remove variations in triggering and bandwidth from repeated source efforts from the down-hole data. The design is to find a filter which matches each source effort to a target trace on the reference phone. This way, we remove variations in the source effort from appearing in the down-hole data. This removal occurs when we re-apply the designed filters on the reference phone to the down-hole data, thus standardizing the embeded wavelet.
 bshp infil  infil2 iswopt iswch tmin tmax npf sf infil3 
  
 infil :   =name of input file #1 
            (file1*filter=file2)  
 infil2:   =name of input file #2 
 iswopt:  0=profile mode 
          1=trace mode 
 iswch:   1= (file#1*filter)=output 
          0= (file#3*filter)=output 
 tmin:     =start time of design gate in seconds 
 tmax:     =end time of design gate in seconds 
 npf:      =number of point in filter 
 sf:       =stability factor (.001 typical)  
 infil3:   =name of input file #3 (iswch=0 only)

Example: If tref.seg is the T-component of the reference phone, and if targ.seg is a target trace (perhaps the last of the source efforts as recorded on that same component, the a shaping filter can be found that matches each source effort to that last effort. Rational is that the last source effort is stable due to the compaction of soil below a hammer source. The command to match each source effort to the target trace might be:


bshp tref.seg targ.seg 1 1 0 0.1 360 .0001

The output file would be bshptref.seg and should be plotted to asses the degree of success and the chosen command line arguments. Then application of the filter designed above to the down-hole data might be done with this command:


bshp tref.seg targ.seg 1 0 0. 0.1 360 .0001 twav.seg

where twav.seg is the file with the original down-hole data which are contaminated by variations in trigger source timing and embedded source wavelet. What happens is that the shaping filters are recomputed with the same design input, but applied this time to the file listed as the last argument on the command line. The shaped down-hole data would be the output file, bshptwav.seg.

The degree to which shaping is helpful depends on how repeatable the source efforts are. With a highly stable and repeatable source, there will not be much difference in the result from shaping. However, with a source that produces variation in triggering or wavelet radiated, the result may be very helpful. Shaping will not hurt unless significantly poor choices are made in the command line parameters.