Whiten

[massimo]

Ciao,
whiten is a method of deconvolution of the signal which helps to improve the resolution the beampower?

This method allows to improve the signal to noise ratio?

In processing based on phases (FK, SPAC) is always useful to use this method?

thanks
massimo

[admin]

whiten is a method of deconvolution of the signal which helps to improve the resolution the beampower?

It is just normalization of the amplitude spectrum with a zero-phase shift.

This method allows to improve the signal to noise ratio?
In processing based on phases (FK, SPAC) is always useful to use this method?

When massively processing noise correlations it helps to remove effects of strong events (earthquakes, explosions,...). Effect on signal to noise ratio probably depends upon the application and the method. For instance F-K beam forming for subsurface site characterization, whitening is not recommended as transient strong and far sources may bring substantial and correct information. In a case where there are many local and close sources inside the array, whitening may help to improve the performances of the array processing. I think it is rather site and ambient sources dependent. I'm not aware of any complete study testing the pros and cons of whitening in those cases. Do you have any literature reference about that?

For SPAC processing whitening does strongly alter the results. The processing relies on phases but on the amplitudes as well.