Design And Implementation Of Marine Digital Magnetic Heading System

Heading direction is a so important parameter to moving carriers, Especially when ships are sailing, whether or not to obtain the ships' heading direction real-timely and accurately is momentous to navigation safety. Given the prevalent application of heading direction on navigation, this paper designs a marine digital magnetic heading system based on magneto-resistance sensor, which mainly realizes the function of measurement and display of heading angle. This system is composed of two relatively independent sub-modules, magnetic compass sensor module, which is designed with AVR MCU of ATMEL as controller and HMC1022 of Honeywell as magnetic sensor, and displaying module, which is designed with AVR MCU of ATMEL as controller and LED dot matrix as displaying component. As the system works, firstly magnetic compass sensor module, which is installed on the surface of magnetic compass, acquires magnetic field around magnetic compass. Secondly this module makes magnetic signals amplified, A/D converted, filtered and etc. And following in order to implement mathematical operation on hardware simply, CORDIC algorithm is adopted to calculate heading angle. And then heading angle is transmitted out through serial interface in format of NMEA 0183. At last, it is displayed on LED dot matrix by the displaying module. The whole system not only realizes the functions of heading angle measurement (error of less than 1°, between 0°and 360°in the two dimensions) and display, but also realizes intercommunication between machine and user, which is to say, user can adjust displaying brightness and set course deviation manually. Meanwhile basic navigation data can be provided to AIS, auto-steering, ship radar and so on by the serial interface of system to realize auto-navigation.The system, which mainly deals with micro-electronics technology, sensor technology, display technology and communication technology and so on, has gone through the whole process from studying algorithm, system designing, hardware configuration, software programming and system debugging. Through testing, it can be concluded that the prototype has met the design requirements of small size, low cost and credible and stable performance.This paper mainly introduces several parts of contents, including development of magnetic heading system, principle of magneto-resistive sensor, CORDIC algorithm, hardware circuit design, system software design and system debugging.