## OpenWave #9 : Measuring significant wave height in the frequency domain

The last post looked at two time domain measurements of significant wave height, the highest 3rd calculation and the 4 times the standard deviation measurement. It turns out that the standard deviation measurement can also be made in the frequency domain. This is because the variance of a time domain signal is equal to…

## OpenWave #8: Calculating significant wave height

There are multiple ways of calculating significant wave height (Hs). According to wikipedia, the original definition was the average of the highest 3rd of waves. What this means is you would measure wave heights(trough to crest) for a set period, order that dataset from lowest to highest, take the top 3rd of the values and…

## OpenWave #7 : Displacement measurement results – peak detect vs zero crossing

This post will detail an experiment in which the wave sensor was attached to a rotating arm at three different diameters. These diameters were 40cm, 60cm and 80cm. For each diameter, measurements were taken at two speeds to get an idea of how rotation frequency affects measurement accuracy. This gives a total of 6 sets…

## OpenWave #6 : Getting vertical displacement working

Post #5 outlined the steps used to go from vertical acceleration to vertical displacement and how the results were completely off. The reason why each of the displacement graphs at the end of the post look so totally different just by changing the integral reset points is because of a negative offset to the velocity…