How does Ruskin process tide and wave data?

Outside of the standard pressure sensor parameters (pressure, sea pressure, depth), the tide and wave processing provides these additional parameters:

Parameter Mode How it’s calculated

Tidal slope

|tide16 or
|wave16

The tidal slope is calculated using a 15-sample window centred around the point of interest. The values are weighted with discrete Fourier transform (DFT) coefficients and averaged over a window function.

Significant wave height and period

|wave16

The average of the first 3rd of the wave height/period values sorted in descending order of height.

Ten percent wave height and period

|wave16

The average of the first 10th of the wave height/period values sorted in descending order of height.

Maximum wave height and period

|wave16

The maximum of the wave height/period values

Average wave height and period

|wave16

The average of the wave height/period values

Wave energy

|wave16

Wave energy = Variance (m4) * gravity (m/s2) * density (kg/m3)
Wave energy units are Joules.
Variance = 1/2 A2 (m4)
Variance is the average over one wavelength of the surface elevation squared.
The first (partial) wave is ignored for averaging purposes, though it is counted for the variance and wave energy.

More details can be found in the publication, Performance of a new submersible tide-wave recorder.