China to build satellite navigation system

China has started to build its own satellite navigation system, called Compass.

The planned network, also referred to as Beidou in Chinese, entails the launching of five geostationary Earth orbit (GEO) and 30 medium Earth orbit (MEO) satellites, informed sources said here Thursday.

China plans to launch two Compass navigation satellites at the beginning of next year. The system is expected to cover China and parts of neighbouring countries by 2008 before being developed into a global constellation, according to the sources.

The system will provide two navigation services. The Open Service is designed to provide users with positioning accuracy within 10 meters, velocity accuracy with 0.2 meter per second and timing accuracy within 50 nanoseconds.

The Authorized Service will offer "safer" positioning, velocity, timing communications for authorized users.

More details can be found here.