Short answer
Chinese GNSS, fully operational with BDS-3 since 2020. Broadcasts global civilian signals on B1I/B1C (1561 / 1575.42 MHz), B2a/B2b (1176.45 / 1207.14 MHz), and B3I (1268.52 MHz), plus the unique BDS RDSS short-message service.
Detailed explanation
BeiDou (BDS) is China's GNSS, operated by CSNO. The system completed deployment in 2020 with 30 satellites in MEO, IGSO, and GEO orbits — a hybrid configuration that provides enhanced coverage over the Asia-Pacific region in addition to global service.
BDS broadcasts both legacy BDS-2 signals (B1I at 1561.098 MHz, B2I at 1207.14 MHz, B3I at 1268.52 MHz) and modernised BDS-3 signals (B1C at 1575.42 MHz interoperable with GPS L1 / Galileo E1, B2a at 1176.45 MHz interoperable with GPS L5 / Galileo E5a, B2b at 1207.14 MHz carrying the free PPP-B2b precise corrections). Most modern multi-constellation receivers process B1C + B2a + B3I as their primary BDS signals.
BeiDou's unique offering is the Radio Determination Satellite Service (RDSS) — two-way satellite messaging over BDS GEO satellites. Users can send short text messages and emergency reports globally without cellular infrastructure, making BDS the only GNSS with a built-in communication channel. This drives a separate product family of L-band Tx + S-band Rx antennas.
BDS-3 also broadcasts a PPP-B2b service on the B2b signal — free precise orbit and clock corrections that converge to ~10 cm horizontal in 10–30 minutes anywhere in the Asia-Pacific footprint, no subscription required.
Where you'll see this
BDS Short Message Communication
Browse product lineRelated terms
GNSS
Umbrella term for any constellation of satellites providing global positioning, navigation, and timing. The four global GNSS systems are GPS (US), GLONASS (Russia), Galileo (EU), and BeiDou (China); QZSS (Japan) and NavIC (India) are regional.
RDSS
BeiDou's unique two-way satellite messaging service. Users transmit a short message + position request on L-band uplink (1610–1626.5 MHz), and receive a response + correction on S-band downlink (2483.5–2500 MHz). The only GNSS with built-in global SMS-grade communication.
PPP
A precise GNSS positioning technique using globally-broadcast precise orbit, clock, and atmospheric corrections to deliver decimetre-to-centimetre accuracy with a single receiver — no local base station required. Convergence times of 10–60 minutes for cm-level; instant for decimetre via PPP-RTK.
L-band
The 1–2 GHz radio frequency band used by virtually every GNSS civilian signal. Most public GNSS signals cluster around 1176 MHz (L5/E5a/B2a), 1227 MHz (L2), 1561–1602 MHz (L1/E1/B1/GLONASS L1), and 1268–1278 MHz (B3I/E6).