Whitten application

Discuss here all technical and scientific questions about the processing of ambient vibrations for site characterization (H/V, Array methods,...)
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Whitten application

Postby shaham » Sun Aug 21, 2011 6:16 am

Dear Dr.Wathelet
I want to know
-The theory of the "whiten" ability and its application.
-Is it useful or not to use "whiten" before a H/V process run?

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Postby admin » Wed Sep 21, 2011 2:36 pm

"whiten" is simply setting the amplitude of signal spectra to 1 for all frequencies. This operation keeps the phase of the spectra untouched. Hence this operation is a valid pre-processing for processing based on phases (FK, SPAC, correlations,...).

With H/V, you'll get a flat curve in all cases, located around 1. Based on amplitude differences between vertical and horizontal components, H/V is strongly affected by a whitening process. So NEVER run a "whiten" before processing H/V. You would conclude erroneously that all sites behave like rock sites.

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