Beidou navigation satellite system-"BDS" is a global satellite positioning and communication system developed by China itself, and it is the third mature satellite navigation system after the US global positioning system and Russian global satellite navigation system. The system consists of space terminal, ground terminal and user terminal, which can provide high-precision and high-reliability positioning, navigation and time service for all kinds of users around the world all day, and has the ability of short message communication. It has the ability of regional navigation, positioning and timing, with positioning accuracy better than 20m and timing accuracy better than 100ns. 201212 On February 27th, the official version of Beidou system spatial signal interface control file 1.0 was officially released, and Beidou navigation service officially provided passive positioning, navigation and timing services to the Asia-Pacific region. 20 14 10 month, 1 1, the international maritime organization approved the Beidou satellite navigation system. On July 25th, 2005, the Long March 3B/ Expedition I carrier rocket was launched in xichang satellite launch center.