michaelkoopmans asked: When a wave spectra is calculated, isn't a response amplitude operator utilized? Where does the Datawell sensor get this information? Or has Liquid Robotics estimated this statistic using a combination of wave tank testing and computer simulations?

The filter response of the instrument is determined ahead of time.  In addition,  there is of course the hydrodynamic response of the glider with its length and width in relation to the wave length.  This was examined when the glider travelled a square trajectory, The resulting spectra showed only little differences due to slowly changing wave conditions, rather than hydrodynamic response issues.

LB