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### Topic: Detect Wave Height (Read 2057 times)previous topic - next topic

#### fender21

##### Nov 25, 2012, 04:00 am
Hi all,
I am attempting to build a water buoy which could determine wave height.  The problem is I have no idea how I would calculate such a thing, any thoughts on what types of tools could be used to estimate this kind of information?

#### arduinopi

#1
##### Nov 25, 2012, 04:18 am
although I have little experience. I know you will need a gyro, a accelerometer or both and could use those to calculate the movement of the buoy vertically as well as tilting.
All of my projects --> http://www.frankmagazu.com/

#### zoomkat

#2
##### Nov 25, 2012, 07:51 am
Have you researched how the current buoys measure wave height?
Why I like my 2005 Rio Yellow Honda S2000  https://www.youtube.com/watch?v=pWjMvrkUqX0

#### PeterH

#3
##### Nov 25, 2012, 12:51 pm
I would have thought your best bet would be to make a buoy heavily biased to a vertical orientation, with an accelerometer to measure vertical displacement. For a lower-tech solution I'd look for a oscillating spring/mass system to measure displacement.

#### robtillaart

#4
##### Nov 25, 2012, 09:25 pm

3d axis accelerometer to to measure acceleration,
integrate acceleration over time to get the speed,
integrate speed over time to get distance

That is the theory

it boils down to a formula like  height = sum(0.5*a*t^2)   // sum as long as the vertical acceleration has the same sign. if the sign swaps start over again.

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

#### fender21

#5
##### Nov 26, 2012, 11:05 pm
Thanks all.  I ran across this statement by NOAA on how it's caclulated. I'm not sure I can translate it into an actual number but it sounds like a fun project to play around with:

NDBC-reported wave measurements are not directly measured by sensors on board the buoys. Instead, the accelerometers or inclinometers on board the buoys measure the heave acceleration or the vertical displacement of the buoy hull during the wave acquisition time. A Fast Fourier Transform (FFT) is applied to the data by the processor on board the buoy to transform the data from the temporal domain into the frequency domain. Note that the raw acceleration or displacement measurements are not transmitted shore-side. Response amplitude operator (RAO) processing is then performed on the transformed data to account for both hull and electronic noise. It is from this transformation that non-directional spectral wave measurements (i.e., wave energies with their associated frequencies) are derived. Along with the spectral energies, measurements such as significant wave height (WVHGT), average wave period (AVGPD), and dominant period (DOMPD) are also derived from the transformation.

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