Electronic compass, also known as digital compass, has been widely used as a navigation instrument or attitude sensor in modern technical conditions. Compared with the traditional analog and balanced frame structure compass, the electronic compass has low energy consumption, small size, light weight, high precision and miniaturization. Its output signal can be digitally displayed through processing, which can be used not only for pointing, but also for digital signals. Directly sent to the automatic rudder to control the operation of the ship. At present, the three-axis strap-down reluctance digital magnetic compass is widely used. This compass has anti-shake and anti-vibration, high heading accuracy, electronic compensation for the interference field, and can be integrated into the control loop for data link. Such advantages, and thus widely used in aviation, aerospace, robotics, navigation, vehicle navigation and other fields.