January 08, 2013
China has declared its Beidou satellite navigation system fully operational, although the service remains limited to most of the Asia-Pacific region.
The operating office says it is “accelerating” construction of the system, but repeats its longstanding commitment to achieve global coverage by about 2020; no earlier possibility is mentioned.
“At present, the in-orbit satellites and ground systems are under stable operation, various user terminals have passed test and assessment, and system service performances can fulfill designed parameters and requirements,” the Beidou Navigation Satellite System office says. Initial operational service began a year ago.
The system appears to have been rebranded. For many years it had an English name, Compass, to help with international marketing. But now only the established Chinese name, Beidou, meaning Big Dipper, is being used — along with the abbreviation BDS, which is probably intended to correspond to the U.S. GPS. The name is pronounced like the two English words “bay” and “doe.”
Beidou offers horizontal and vertical positioning precision of 10 meters (33 ft.), velocity within 0.2 meters per second, timing precision of 50 nanosec., and a two-way, high-precision timing and short-message communications service.
The complete system around 2020 is intended to have 35 satellites. The intended five in geostationary orbit and five in inclined geostationary orbit are already aloft, with only four of the intended 27 medium-orbit satellites.
The geostationary satellites are 58.75 deg., 80 deg, 110.5 deg., 140 deg. and 160 deg. east of Greenwich. The inclined geostationary and medium-orbit satellites are in orbits 55 deg. from the equator.
The system office has published the signal interface control document in English at its website, en.beidou.gov.cn.