Short answer
Regional augmentation services that broadcast corrections and integrity data over GNSS L1 / L5 frequencies to improve accuracy and safety. Examples: WAAS (US), EGNOS (Europe), MSAS (Japan), GAGAN (India), SDCM (Russia), KASS (Korea), BDSBAS (China).
Detailed explanation
SBAS systems are geostationary or geosynchronous satellites that retransmit GPS-like signals at L1 (1575.42 MHz, BPSK(1)) and L5 (1176.45 MHz, BPSK(10), modernised SBAS) carrying corrections derived from a regional network of monitoring stations. A receiver that supports SBAS gets ranging from the SBAS satellite plus pseudorange corrections plus integrity bounds for every GNSS satellite in view.
The civilian aviation industry is the primary driver — SBAS provides the integrity (probability of misleading information bounded to 10⁻⁷ per approach) required for ICAO LPV / LP / APV approaches. Outside aviation, SBAS gives ~1 m accuracy for free everywhere it's available, much better than GPS alone.
Active SBAS systems by region: WAAS (continental North America), EGNOS (Europe + North Africa), MSAS (Japan), GAGAN (India), SDCM (Russia), KASS (Korea Republic), BDSBAS (East and Southeast Asia). Each covers a few-thousand-km footprint and is not interchangeable — you need the SBAS broadcast for the region you're in.
Modern SBAS uses dual-frequency L1 + L5 broadcasts (DFMC SBAS) for ionospheric correction without needing the receiver to interpolate the iono delay locally. Any GNSS antenna that covers L1 + L5 is SBAS-compatible.
Where you'll see this
High-Precision GNSS Measurement
Browse product lineRelated terms
GPS
United States DoD-operated GNSS, fully operational since 1995. Broadcasts civil signals on L1 (1575.42 MHz), L2 (1227.6 MHz), and L5 (1176.45 MHz), plus restricted military M-code on L1 and L2.
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).