White Paper

w w w. m r c y. c o m WHITE PAPER Mercury's BuiltSAFE ROCK2 OpenVPX development system forms the basis of the ECCP processing subsystems. Overview The satellite-based augmentation system (SBAS) concept uses global navigation satellite system (GNSS) measurements and precisely located reference stations that are deployed across the whole coverage area. GNSS measurements are transferred to a processing center, which calculates differential corrections, and integrity messages, which are subsequently broadcast using geostationary satellites as an augmentation or overlay of the original GNSS message. EGNOS, which is the European SBAS V3 ground segment, manages signals from GPS and Galileo satellites. The figure below shows a simplified overview of the global architecture for EGNOS V3. Only the subsystems where ECCP is deployed are shown: • Ranging integrity monitoring station (RIMS) • Central processing facility (CPF) • Navigation land earth station (NLES) The EGNOS V3 Program The European Geostationary Navigation Overlay Service (EGNOS) is a key contributor to the global navigation satellite system and is currently in its service provision phase under the responsibility of the European GNSS Agency (GSA). EGNOS V3 replaces V2, which has been operational since 2011 and will be the basis for the future European satellite base augmentation system (SBAS). This system will provide advanced safety-of-life and other new services to maritime, aviation and land users. EGNOS V3 is capable of processing the signals from modernized GPS and the new Galileo constellations that replace EGNOS V2. Further, EGNOS V3 has backward compatibility with V2 technology and benefits from capabilities offered by the new global navigation satellite system (GNSS) and its dual frequency multi-constellation technology. EGNOS V3 Architecture Overview The EGNOS V3 compute architecture allocates system functions to multiple subsystems while addressing safety, security and operation considerations. Data is processed according to one of four primary functional domains listed below: • Collection • GNSS and SBAS measurements are collected via two separated ranging integrity monitoring station (RIMS) chains. One chain feeds the central processing facility (CPF) prediction chain and the other provides data to the integrity chain. This approach enables independent integrity moni- toring at the processing stage. • Processing • CPFs provide the processing function for single frequency and dual frequency services. • Dissemination • Switches are optimized for enhanced availability and continuity. • Exchange • Some cryptographic mechanisms provide authentication and data integrity at the software application level. EGNOS V3 Computing Elements The EGNOS V3 architecture is optimized for reduced complexity through generic and centrally managed line replacement units (LRU) computing platforms. Two families of generic common processing units are used within the system: ECCP systems including RIMS, central processing facility (CPF) and navigation land earth station (NLES) host real-time software with various safety, security and performance levels. Other systems that host non real-time software typically run other operational support functions. 2

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