地磁传感器文章，包括EMS地磁传感器、地磁导航技术及其应用、基于磁传感器MMC212的电子指南针、基于地磁原理的计转数传感器技术研究、水平定向钻进随钻姿态测量及误差补偿-Geomagnetic sensor article, including EMS magnetic sensors, magnetic navigation technology and its applications, based on magnetic sensor MMC212 electronic compass,