BeiDou
The BeiDou Navigation Satellite System (BDS; Chinese: 北斗卫星导航系统; pinyin: běidǒu wèixīng dǎoháng xìtǒng) is a satellite-based radio navigation system owned and operated by the China National Space Administration. It is one of the global navigation satellite systems (GNSS) that provide geolocation and time information to a BDS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more BDS satellites. It does not require the user to transmit any data, and operates independently of any telephonic or Internet reception, though these technologies can enhance the usefulness of the BDS positioning information.
Logo of BeiDou | |
| Country/ies of origin | China |
|---|---|
| Operator(s) | CNSA |
| Type | Military, commercial |
| Status | Operational |
| Coverage | Global |
| Accuracy | 3.6 m (global, public) 2.6 m (Asia Pacific, public) 10 cm (encrypted) |
| Constellation size | |
| Nominal satellites | 30 |
| Current usable satellites | 35 |
| First launch | 31 October 2000 |
| Last launch | 23 June 2020 |
| Total launches | 59 |
| Orbital characteristics | |
| Regime(s) | GEO, IGSO, MEO |
| Orbital period | 7⁄13 sd or 12 hours and 53 minutes |
| Revisit period | 7 sidereal days |
| Website | en |
| Geodesy |
|---|
The current service, BeiDou-3 (third-generation BeiDou), provides full global coverage for timing and navigation, along with Russia's GLONASS, the European Galileo, and the US's GPS. It consists of satellites in three different orbits, including 24 satellites in medium-circle orbits (covering the world), 3 satellites in inclined geosynchronous orbits (covering the Asia–Pacific region), and 3 satellites in geostationary orbits (covering China). The BeiDou-3 system was fully operational in July 2020. In 2016, BeiDou-3 reached millimeter-level accuracy with post-processing.
Predecessors included BeiDou-1 (first-generation BeiDou), consisting of three satellites in a regional satellite navigation system. Since 2000, the system has mainly provided navigation services within China. In December 2012, as the design life of BeiDou-1 expired, it stopped operating. The BeiDou-2 (second-generation BeiDou) system was also a regional satellite navigation system containing 16 satellites, including 6 geostationary satellites, 6 inclined geosynchronous orbit satellites, and 4 medium earth orbit satellites. In November 2012, BeiDou-2 began to provide users with regional positioning services in the Asia–Pacific region. Within the region, BeiDou is more accurate than GPS.: 179
In 2015, fifteen years after the satellite system was launched, it was generating a turnover of $31.5 billion per annum for major companies such as China Aerospace Science and Industry Corporation, AutoNavi, and Norinco. The industry has grown an average of over 20% in value annually to reach $64 billion in 2020.