The Design Of Digital Phone System Based On Laser Communication

Electric compass is a sensor used to determine direction with the help of geomagnetic field. With the development in science and technology, electric compass are being used in a wider range of fields. It plays a more and more important role in the national defence, industry and everyday life. For some reasons, the reseach of electic compass starts late in China, and it is still in a low level. Therefore, in order to meet people's increasing demand for electric compass and to do further research of it, it becomes nessary and practical to develop a more advanced product of high stability, high sensitivity, moderate precision and low cost, which can be easy to operate and massively produce.Considering the current situation of electric compass, the paper focuses on the development of fluxgate compass and it explains the theory of fluxgate and introduces the calculational methods of the fluxgate probe. A fluxgate probe of low volume and high precision and fluxgate signal circuit are designed to transform fluxgate signals into standard signals so that they can be easily connected to relevant equipments. And the paper detailedly explains the designing of electric compass. To solve the complex problem of software compensation of electric compass, the orthogonal accommodator and suspended device of dual-axies fluxgate magnetometer are designed so that the compass can keep high precision and remain working even when gradient. The functions of zero compensation and sensativity adjustmentare designed in magnetic deviation compensated circuit in order to remove the effect of environmental ferromagnet on the compass. Test is carried out to measure the precision and time-drift in the finished compass, which is characterized by its low volume and high precision, and the result is in the expectation.A/D switching circuit and the serial port communication circuit are also designed; they are controlled by MCU to gather the electrical signals and deliver them into PC, in which the signals are received and processed with VC++ programme language to find the real-time ture course. A vedio interface visual is made to display the real-time ture course, which makes possible the human-computer contact. According to the experiment data made in this paper, the error of this real-time ture course displayed in PC is less than 0.3°, which can meet the precision demand in most situations.