The BeiDou Navigation Satellite System (BDS for short, hereinafter referred to as the BeiDou system) is built by the Chinese government and provides all-time, all-weather and high-accuracy positioning, navigation and timing services to global users. BeiDou is the name of the parts of the great bear constellation in ancient China, which is used as the identification direction in ancient times. Now it merges the latest scientific and technological achievements of mankind, and gives a new connotation to "BeiDou".
The construction of the BeiDou system was divided into three stages. At the end of 2000, the BD-1 system was built to provide services to China. At the end of 2012, the BD-2 system was built to provide services to the Asia-Pacific region, and around 2020, the BD-3 system will be built to provide services to the world.
- BD-1 Constellation
- BD-2 Constellation
- BD-3 Constellation
(1) The space segment. The BDS space segment is a hybrid navigation constellation consisting of GEO, IGSO and MEO satellites.
• The basic constellation of BD-2 is 5GEO+5IGSO+4MEO.
• BD-3 is composed of 3GEO+3IGSO+24MEO constellation, which has communication capability between satellites and satellites, and can operate independently without ground station support.
- BDS GEO
- BDS MEO
(2) The ground segment. The BDS ground segment consists of various ground stations, including master control stations, time synchronization/uplink stations, and monitoring stations.
(3) The user segment. The BDS user segment consists of various kinds of BDS terminals, chips, modules and antennae, as well as application systems and application services.
BD-2 provides B1I, B2I and B3I three public service signals in the three frequency bands of B1, B2 and B3. The center frequency of B1 band is 1561.098MHz, B2 is 1207.140MHz, B3 is 1268.520MHz.
BD-3 provides B1I, B1C, B2a and B3I four public service signals in the three frequency bands of B1, B2 and B3. The center frequency of B1 band is 1575.420MHz, B2 is 1176.450MHz, B3 is 1268.520MHz.
The services of the BD-2 system cover an area extending 55°S-55°N and 55°E-180°E, with positioning accuracy less than 10 meters, velocity measurement accuracy less than 0.2 meter per second, and timing accuracy less than 50 nanoseconds.
BD-2 Service Area
BD-3 will provide global coverage with space signal accuracy less than 0.5 meters, and the design indicators of space signal continuity, integrity and usability are all at the top level in the world.