BeiDou-3 MEO

China's BeiDou Navigation Satellite System achieved full global operational capability in July 2020 when the final BeiDou-3 satellite was launched. The system began providing global positioning, navigation, and timing services in late 2020, completing a multi-decade development program. This milestone made BeiDou the fourth global navigation system alongside GPS, GLONASS, and Galileo.

The BeiDou-3 Medium Earth Orbit (MEO) component consists of 24 satellites operating at approximately 21,500 kilometers altitude, forming the backbone of the global system. These are complemented by 6 satellites in inclined geosynchronous orbits (IGSO) and 3 in geostationary orbits (GEO), bringing the total BeiDou-3 constellation to 33 satellites. The MEO satellites complete an orbit every 12 hours and provide worldwide coverage.

BeiDou-3 provides global service with positioning accuracy of approximately 10 meters, though in the Asia-Pacific region where additional GEO and IGSO satellites provide enhanced coverage, accuracy improves to approximately 5 meters. Test results have shown real-time accuracy as good as 2-3 meters in some areas. BeiDou-3's accuracy is generally comparable to modernized GPS, with the system also offering unique short message communication capabilities not available from other GNSS systems.

BeiDou-3 offers unique short message communication (SMC) capability that allows users to send text messages through the satellite system without requiring a cellular network, a feature not available from GPS or other GNSS systems. The BeiDou-3 system expanded the message capacity from the original 120 Chinese characters in BeiDou-1/2 to 1,000 Chinese characters (approximately 2,000 bytes) per message in BeiDou-3. This capability is particularly valuable for users in remote areas, maritime applications, and emergency communications.