The procedure described in this article is only necessary for specific instruments and is intended for users who have been specifically instructed by Nortek to perform it.
For information about the standard compass calibration workflow, please refer to the Compass calibration article, which describes both the standard 2D and 3D calibration procedures. A standard 2D calibration should always be performed prior to deployment.
Ensure that your instrument is running the latest firmware version.
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Place the system in a suitable calibration area.
Keep the system away from magnetic disturbances. Strong magnetic fields (above approximately 5 Gauss) can distort the calibration. Avoid large steel objects and electronic devices such as phones and watches.
Ensure that you have sufficient space to slowly rotate the instrument around all three axes during the calibration.
The instrument should not be mounted in deployment equipment (e.g. buoys) and should not contain batteries.
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Connecting to the software
Connect the instrument to the configuration software and open the Compass Calibration window (found under the Instrument tab in Signature Deployment and under the Calibrate tab in Nortek Deployment).
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Starting the calibration
In Signature Deployment, select 3D and Calibrate, as shown in the screenshot below.
In Nortek Deployment, select 3D, as shown in the screenshot below.
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Start the calibration procedure
Click Start to begin collecting data.
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Rotate the instrument.
Rotate the instrument slowly and steadily around all three axes.
The software visualizes the coverage in the XYZ space with blue data points. The red arrows represent individual octants of the measurement space. Each arrow turns green once sufficient data points have been collected within that octant.
A minimum of 50 data points per octant is required.
Continue rotating the instrument until all arrows turn green.
If you need guidance on how to move the instrument to achieve full coverage, refer to the video below, which shows a suggested movement pattern.
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Stop the data collection.
Once all arrows have turned green, click Stop.
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Inspect the Quality indicator
Confirm that the quality indicator is acceptable.
Green: Estimated magnitude error < 2%
Corresponds to a maximum heading error of approximately 2°, consistent with the instrument specification.Yellow: Estimated magnitude error 2-6%
Corresponds to an expected heading error of approximately 2°-5°.Red: Estimated magnitude error > 6%
Indicates that the resulting heading error is likely to exceed 5°, and the calibration should be repeated.
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Apply the calibration offsets.
Click Update and confirm that the new offset values are transferred to the instrument. A confirmation pop-up will appear once the offsets have been successfully saved.
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Verify the calibration.
Repeat Steps 3–7, ensuring that the Verify option is selected before starting.
The resulting sphere should be centered near (0, 0, 0) and the offset corrections should be close to zero. This confirms that hard iron magnetic influences have been properly compensated.
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Perform a standard 2D calibration before deployment
After completing and uploading the 3D calibration, the system can be prepared for deployment as usual.
When performing future 2D calibrations, only the X and Y offsets will be updated, while the Z offset from the 3D calibration will be retained.
Video demonstrations
Below are two videos demonstrating how to perform a 3D calibration.
https://vimeo.com/1181935377?share=copy&fl=sv&fe=ci
Updated