APPLICATION OF THE RECURSIVE-APPROACHING SIGNAL FILTER (RASF) TO VSP DATA-PROCESSING

The recursive-approaching signal tilter (RASF) is a newly developed fi ltering technique that combines many advantages of linear, nonlinear, and adaptive filters. It passes step functions without altering them a nd removes many types of noise, such as Gaussian and Laplacian distrib uted noise. When applied to VSP data processing, the RASF emphasizes t hose abrupt discontinuities that originate or terminate at discrete de pth points and effectively accomplishes the separation of upgoing and downgoing wave modes. The RASF may be transformed into a desired filte r by simply changing a parameter to achieve the maximum usefulness of VSP field data. In the tests with the synthetic VSP modeling data corr upted by white Gaussian noise and real VSP data, the RASF compares fav orably to f-k velocity and median filtering methods in removing noise, preserving step functions, and computational simplicity.