说明：  Global Positioning System的缩写,意为利用卫星导航进行测时和测距,以构成全球卫星定位系统。是美国国防部主要为满足军事部门对海上、陆地和空中设施进行高精度导航和定位的需要而建立的。
(Acronym for Global Positioning System, which means the use of satellite navigation for measuring time and distance, to form the global satellite positioning system. U.S. Department of Defense primarily for military departments to meet the sea, land and air facilities for high-precision navigation and positioning needs to establish.)