BNO080 is a device sold and supported by Hillcrest Labs, I do not know the details on that part number. For BNO055 in this case, you would use NDOF mode. As long as the mast is not ferromagnetic, 3 meters distance to the vehicle should be enough to get a good accuracy. In your validation tests, once gyroscope and magnetometer calibration are 3/3, verify that while in operation the magnetometer calibration stays 3/3. The contrary would indicate distorted magnetic field. If the device is rotating relatively quickly, then NDOF mode is well suited. In case of very small rotation speeds, COMPASS mode should be used. o_o
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