In the early morning of June 25, 2019, the 46th Beidou navigation satellite was successfully launched. The successful launch marks the completion of the basic networking of China's Beidou No. 3 system and will provide basic navigation services to countries and regions along the “Belt and Road” before the end of this year.
The Beidou No. 3 is organized in three steps in accordance with the simple system, the basic system, and the global system. At the end of March 2018, the simplest system consisting of 8 Beidou navigation satellites was completed. After the launch of the 18th and 19th satellites of Beidou 3, the basic system constellation was completed. From the mathematical point of view, it can meet 4 satellites at any position in the world. The requirements of the navigation service were realized, and the official use of Beidou began.
Compared with the second-generation satellites, Beidou No.3 has not only expanded its coverage from the Asia-Pacific region to the whole world, but also adopted higher performance cesium atomic clocks and hydrogen atomic clocks. The frequency accuracy and stability have been increased by an order of magnitude, and the positioning accuracy has been further improved to 2.5 meters to 5 meters, 1 to 2 times higher than Beidou 2. In terms of service development, the company will further improve its basic navigation service capabilities, satellite-based enhanced services and international search and rescue services. On the basis of full compatibility with the Beidou II short message service, the service capacity will be increased by 10 times. In the transition process of Beidou No. 2 to Beidou No.3, it is possible to ensure that old users have no perception, new users to provide performance, and finally realize the new and old technology replacement, which is a major upgrade of China's information infrastructure.
The unique communication function will become the new standard communication service mode: Satellite navigation includes both active and passive. The GPS system adopts a passive mode and can only receive navigation satellite signals in one direction, while the Beidou 3 uses a combination of passive and active, and has a short message function, that is, the satellite positioning terminal and the satellite or ground station can directly Two-way information transmission through satellite signals can both locate and display the location of the publisher. Short messages mean more efficient information transmission, especially in the case that ordinary mobile communication signals cannot be covered (such as damage to wireless communication base stations after earthquake disasters, power interruption, field operations, etc.), Beidou terminal can pass short report Text for emergency communication. The short message function has strong application value in the fields of national defense, people's livelihood and emergency rescue, and will be combined with communication technology facilities to become a standardized communication service mode.