Some power spectral density test specifications are too high in amplitude for a given shaker system. Bandsplitting can be cautiously used in these cases.
Here is a brief guideline paper: bandsplit.pdf
Here is a Matlab script that implements bandsplitting per the guidelines: bandsplit.zip
The main script is bandsplit.m. The remaining scripts are supporting functions
Here is an example: bandsplitting_example.pdf
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A bandsplitting function is also included in: Vibrationdata Matlab GUI Package
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See also:
Random Vibration & Power Spectral Density Page
– Tom Irvine