If you are interested in wave data from your AWAC then chances are that you have a ProLog installed to process the raw wave data and give you usable wave parameters in real-time. If you have set your deployment to XYZ then you might be surprised to see that the processed wave data are presented in ENU coordinates. This is normal and is just how the ProLog and processing works.

Waves are processed in Beam coordinates and then all directional estimates are reported in ENU. There has never really been an application where we needed to operate in XYZ – this includes other platform mounted AWACs. These applications always used the “heading offset” to correct for the uncertainty in (a) the orientation of the AWAC at depth (which way is X and Y), and (b) any effects on the magnetometer. This is done by observations, for example, “the waves are clearly coming for the direction of 190 degrees today, so we will estimate the offset based on this”.

To go from ENU to XYZ should just be a matter of subtracting the reported heading value from the wave directions and you have referred the wave direction to the instrument X axis. If you are measuring in ENU, but you cannot trust your compass readings; you can still use your XYZ directions if these are known, then you can eliminate any magnetic uncertainties. If you know where your X axis is pointing relative to North then you can adjust for this with an offset in post processing.

Your current data will be collected in the coordinate system chosen regardless of the ProLog.

If you have any questions please send us an email at support@nortekgroup.com.