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Prolog outputs in ENU coordinates even if the instrument is configured in XYZ

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    Kristin Svingen

    Even though the instrument is set up to measure in XYZ-coordinates, we unfortunately only have functionality for outputting processed wave data from the prolog with directions relative to ENU-coordinates. The raw data relative to the coordinate system you configure the AWAC with (in this case XYZ) is stored on the recorder, but it is not possible to access this through serial output.

    If you do not trust the reported heading in your output data, you will have to find the true heading of your instrument from an external source that is not affected by the local magnetic field and use this to correct the ENU velocities or convert back to XYZ. If your instrument is fixed with X pointing exactly westward your true heading will be 270 degrees. The difference between this value and the reported heading from the AWAC will give you the offset that is due to the local magnetic interference (in this case because of the iron at the site). You can apply this to the data to correct the reported ENU wave directions or perform a coordinate transform to get the wave directions in XYZ coordinates.

    You can also read about mounting instruments on a metallic structure and performing coordinate transformations in our FAQs:

    https://support.nortekgroup.com/hc/en-us/articles/360029507852-How-can-we-deal-with-magnetic-influence-when-mounting-an-instrument-near-on-a-metallic-structure-

    https://support.nortekgroup.com/hc/en-us/articles/360029820971-How-is-a-Coordinate-transformation-done-

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