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Few questions about Linear FK and more general questions

Posted: Thu Feb 17, 2011 10:18 am
by tahoser
Hello Marc,

I have few questions about the linear FK. In fact, I have lines of geophones but there are not straight lines and then the linear Fk separates my lines on sub-lines, and so it takes 1 or 2 geophones sometimes, and the results associated is not very good (file attached).
Then, I have several questions:
-how can I know the sensors selected to calculate each result of the linear FK for each line (and sub-line)
-how can I tell him to do not separate on sub-lines.
-how can I plot the shots on the map with the sensors (a very basic question!)
-and how I can extract the result for each FK analysis on separated file in order to plot a reference dispersion curve on each result.

Thank you for your help on trivial questions.

Estelle

Posted: Wed Mar 16, 2011 11:53 am
by admin
The identification is based on "shots". Distinct shots have distinct:
  • source coordinates;
  • starting time (T0);
  • reference time;
  • rough azimuth from source (same as azimuth from source but comparison of two signals based on this criterion is more relaxed, they must differ by at least 90 degrees to be declared as different).
The last condition states only that all receivers must be on the same side of the shot location. If a shot point is in the middle of a line, the line of receivers is viewed as two distinct shots.

This is designed for active linear experiments with signals imported with option "No common time reference" (do not set a common time reference, each signal has its own). For classical active experiment, T0 is equal to the pre-trigger delay and is the same for all signals in the same shot. Time reference is then the absolute time of shot record and is different for all shots, for instance several shots at the same location for stacking.