Overview
ISO 18197:2015 - Space systems: Space based services requirements for centimetre class positioning defines system and verification requirements for delivering centimetre‑level positioning over a wide area by broadcasting augmentation data via satellites. The standard targets real‑time services (e.g., PPP corrections broadcast from augmentation satellites) that allow user terminals to resolve carrier‑phase ambiguities and achieve centimetre accuracy across wide regions (for example, areas on the order of 1,000 km per side) without relying on local ground networks.
Key topics and requirements
- Scope and purpose: Requirements for space‑based augmentation services that broadcast augmentation data (satellite clock/orbit corrections, ionospheric information, etc.) to enable wide‑area centimetre‑class positioning in real time.
- System elements covered: augmentation satellites, augmentation satellite control stations, ground reference points, positioning augmentation centres, uplink/downlink data flows and user terminals.
- User terminal requirements: capability to ingest augmentation data and perform real‑time ambiguity resolution (fixing) for carrier‑phase positioning; pre‑processing and output specifications are defined.
- Operational requirements: simultaneous operation modes, message structure, and user operational support services to ensure availability anywhere in the coverage area.
- Processing and models: expectations for mathematical models and physical constants used in position computation and augmentation‑data generation.
- Verification & evaluation: detailed criteria and procedures for verification, including evaluation plans, test conditions (time, place, satellites, reference points), accuracy and convergence metrics, and methods for diagnosing malfunctions.
- Informative annexes: guidance on augmentation satellite constellations, antenna coverage, augmentation data rates, and typical applications requiring centimetre accuracy.
Applications and users
ISO 18197:2015 is practically aimed at organizations and stakeholders involved in:
- Providers of PPP and satellite‑based augmentation services
- GNSS/augmentation system designers and integrators
- Surveying, mapping and civil engineering firms requiring certified centimetre accuracy
- Precision agriculture (automatic farming), autonomous vehicles, ITS, marine navigation and disaster monitoring
- Certification bodies and regulators assessing service reliability, availability and verification procedures
These users benefit from standardized requirements that support interoperability, service certification and predictable, wide‑area real‑time centimetre positioning.
Related standards and context
- Complements existing satellite augmentation system practices (SBAS) such as WAAS, EGNOS, MSAS, while focusing on centimetre‑class PPP‑style services rather than metre‑level SBAS integrity.
- Developed by ISO/TC 20/SC 14 (Space systems and operations) to provide uniform requirements and evaluation criteria for space‑based centimetre positioning services.
Keywords: ISO 18197:2015, centimetre class positioning, satellite-based augmentation, PPP, GNSS, real-time ambiguity resolution, wide-area positioning, augmentation data, verification and evaluation.