The constellation
BDS-3 operates on a 30-satellite nominal design: 3 satellites in geostationary orbit (GEO), 3 in inclined geosynchronous orbit (IGSO) and 24 in medium Earth orbit (MEO). The GEO satellites anchor services over China, the IGSO satellites hold high elevation angles over Asia-Pacific and the MEO shell carries the global service. As of the 2024 report by the China Satellite Navigation Office (CSNO), 48 BeiDou satellites were in operation across generations: 15 BDS-2 and 33 BDS-3. The nominal design figure and the operational fleet figure are different numbers, and both are correct in context.
The final BDS-3 satellite launched on 23 June 2020 aboard a Long March-3B from Xichang, and the system was commissioned on 31 July 2020. It has provided global service since, operated by CSNO.
The signal plan
| Signal | Centre frequency | Notes |
|---|---|---|
| B1I | 1561.098 MHz | BPSK, legacy open service |
| B3I | 1268.52 MHz | BPSK |
| B1C | 1575.42 MHz | BOC/QMBOC; shares the band with GPS L1 and Galileo E1 |
| B2a | 1176.45 MHz | Shares the band with GPS L5 and Galileo E5a |
| B2b | 1207.14 MHz | Carries the PPP-B2b service; shares the band with Galileo E5b |
Accuracy in practice
A 2022 peer-reviewed assessment measured signal-in-space ranging error at roughly 0.52 m for the MEO satellites, 0.90 m for IGSO and 1.15 m for GEO, with single-frequency single-point positioning better than 5 m in 3D. In the Asia-Pacific region, B1I positioning achieved 2.30 m 3D accuracy in that study epoch, ahead of the 2.88 m measured for GPS in the same test. Figures of this kind are epoch-specific and should always be read with their measurement date.
PPP-B2b: high precision without a base station
The PPP-B2b service broadcasts precise corrections through the three GEO satellites, delivering decimetre-level kinematic and centimetre-level static positioning, with an official specification better than 0.6 m (30 cm horizontal, 60 cm vertical) and convergence in roughly 14 minutes. It is a regional service covering China and Asia-Pacific, which makes it directly relevant to Malaysian surveying, machine control and precision agriculture without local base-station infrastructure.
What GPS does not have: two-way messaging
Alongside RDSS, the system carries MEOSAR search-and-rescue payloads and the BDSBAS augmentation service. For maritime, remote-area and emergency applications, two-way messaging over the navigation constellation is the capability that changes system design: position reports and distress messages travel over the same space segment that provides positioning.