- Fluxgate compass
The basic fluxgate compass is a simple
electromagnetic device that employs two or more small coils of wire around a core of highly permeable magnetic material, to directly sense the direction of the horizontal component of theearth 'smagnetic field . The advantages of this mechanism over amagnetic compass are that the reading is in electronic form and can be digitised and transmitted easily, displayed remotely, and used by an electronicautopilot for course correction.To avoid inaccuracies created by the vertical component of the field, the fluxgate array must be kept as flat as possible by mounting it on
gimbal s or using afluid suspension system. All the same,inertia l errors are inevitable when the vessel is turning sharply or being tossed about by rough seas. To ensure directional readings that are adequately stable, marine fluxgate compasses always incorporate either fluid or electronicdamping . An alternative is to use a 3-axis fluxgatemagnetometer to provide a 3D flux vector, and the magnetic heading is derived from the flux on a planeperpendicular to gravity, thus providing immunity from pitching, and rolling.Fluxgate compasses and gyros complement one another nicely. The fluxgate provides a directional reference that's stable over the long term, apart from changing magnetic disturbances, and the gyro is accurate over the short-term, even against
acceleration andheeling effects. At highlatitude s, where the earth's magnetic field dips downward toward themagnetic pole s, the gyro data can be used to correct for roll-induced heading errors in the fluxgate output. It can also be used to correct for the roll and heel-induced errors that often plague fluxgate compasses installed on steel vessels.See also
*
compass
*gyrocompass
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