BDS positioning accuracy reaches new level
Recently, Yang Changfeng, a member of the National Committee of the Chinese People's Political Consultative Conference and the chief designer of the Beidou satellite navigation system, said in an interview with the media that six Beidou No. 3 networks were launched in succession to verify the basic framework of the global network of Beidou satellite navigation systems. The six satellites include the twenty-eighth and twenty-four Beidou navigation satellites launched on February 12. And this is just the prelude to the "drama" of Beidou in 2018.
According to professionals, the Beidou 3 program will launch 10 missions in 2018, launching 18 satellites, providing basic services to countries and regions along the "One Belt And One Road" line, and laying a key foundation for completing the networking of more than 30 satellites and achieving global services by 2020. In the follow-up, China will also build a national integrated navigation and positioning timing system with the Beidou system as the core, which will form a complete system in the sky, ground, underwater and indoors, and significantly enhance the national space-time information service capability. As one of the 16 major projects in the medium and long-term development plan of China's science and technology field, building a high-performance and highly reliable Beidou global satellite navigation system is not only the improvement and upgrading of the Beidou regional system, but also the climbing of the world-class satellite navigation system.
Xie Jun, deputy chief designer of the Beidou No. 3 Project and the chief designer of the satellite, said that compared with the Beidou No. 2 regional system, Beidou No. 3 has achieved a number of key technological breakthroughs and can provide users with better service. After the system is built, the performance will be comparable to GPS. The Beidou system will not be able to set up a global ground-based station like GPS. In order to solve the problem of overseas satellite data transmission, the development team adopted the integrated design of satellite and satellite transmission functions to realize the link communication between satellite and satellite, satellite and ground station. Even if the ground station cannot directly contact the Beidou satellite flying on the other side of the earth, data transmission can be realized by communication between satellites. At the same time, inter-satellite link technology can also use the new network protocol, management strategy and routing strategy to allow Beidou satellites to measure each other and automatically “maintain the formation” to reduce the pressure on ground management and maintenance.
The reliability and continuity of satellite navigation systems are facing stringent requirements. Once the service is interrupted, the normal operation of the state and society will be greatly affected. Qi Jun, the general commander of the Beidou No. 3 satellite of the Fifth Institute, said that the Beidou No. 3 satellite has more than 60 days of complete autonomous operation capability, and even if the ground station fails, it can still work normally. At the same time, the satellite is capable of fault self-diagnosis and repair with a design life of more than 10 years by virtue of multiple reliability measures.
The on-board atomic clock is the key device to ensure the accuracy of navigation positioning. The Beidou-3 satellite is equipped with a new generation of cesium atomic clocks developed by the Xi'an Branch of the Fifth Hospital. Its frequency stability is 10 times higher than that of the Beidou-2 system and reaches the world advanced level. This will make the positioning accuracy of Beidou navigation system from 10 meters to meters, and the speed and timing accuracy will also be increased by an order of magnitude. At the same time, the Beidou-3 satellite will also be equipped with a newly developed hydrogen atomic clock of the 203 Institute of China Aerospace Science and Industry Corporation. Its mass and power consumption are larger than that of the cesium atomic clock, but the stability and drift rate are better. The combination of two atomic clocks will help Beidou navigate to any place you want to go.
Qi Chengqi, director of the China Satellite Navigation System Management Office, introduced at the National New Office launch conference in December 2017. Beidou and the Internet, cloud computing and big data integration, built a high-precision space-time information cloud service platform, and launched the world's first acceleration to support Beidou. The auxiliary positioning system service covers more than 200 countries and regions, with users exceeding 100 million and daily service reaching 200 million times. At present, the Beidou system has formed a relatively complete Beidou industrial system including basic products, application terminals and operational services.
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