EGNOS CS Algorithm Prototype
EGNOS is the European Geostationary Navigation Overlay System providing to the users satellite and ionospheric corrections with integrity. The system has been developed by Thales Alenia Space France (prior Alcatel) on behalf of the European Space Agency.
Within this system the Check Set (CS) is responsible for providing integrity to the users - especially also in case of feared events - by checking data coming from a ground monitoring network of roughly 40 stations over Europe and few remote stations in other parts of the world.
CS algorithms check integrity of satellites long-term and fast corrections as well as ionospheric corrections for each ionospheric grid point over Europe. This check is nearly instantaneous so that a time-to-alert of few seconds can be met by the EGNOS system.
The CS algorithm prototype is used as a test tool for operational CS implementation. Any discrepancy in processing must be analysed in very detail and root causes identified, so as to assure correct working and performances of the operational CS implementation.
Work on EGNOS CS algorithm prototypes has started in 1998 and many improvements and new detailed functionalities have been developed and incorporated since then.
Early work is being conducted on EGNOS V3, now for the first time aiming at dual-frequency multi-constellation (DFMC) aviation users.
RIMs NG Breadboard
The RIMS 'New Generation' breadboard development is related to the activities of the definition and development of a 'Multi-Regional-System' in the frame of the GNSS Evolutions Program, as logical extension of the current regional EGNOS capabilities
- by integrating additionally with Galileo E1, E5a and E5b (and potentially E6)
- by considering future GPS L2C and L5 signals
- by considering future SBAS L5 evolutions
- by considering GLONASS (TBC)
In the frame of this first evolution step as part of the GNSS Evolution Program, many activities are running in parallel and have to interact in a co-ordinated manner:
- (evolution from EGNOS) MRS study (two parallel contracts for TAS-F and INDRA), for initial assessment of system architecture with multi-frequency, multi-constellation and multi-broadcast capability for regional navigation
- (evolution from ESTB) SPEED, the MRS (EGNOS Evolution) prototyping platform, based on the current operational EGNOS HW & SW (one contract for TAS-F)
- (evolution from L1 NLES) NLES L1/L5 prototype (NLLP), assuming a transponder concept on the GEO satellite, as an evolution of the current L1 transponder concept (to cover SBAS augmentation for GPS IIF L5 signals)
- (evolution from Galileo payload) Generative regional payload breadboard (in contradiction to transponder concept), enabling to generate EGNOS (SBAS) L1/L5, but also Galileo signals
- (evolution from current EGNOS/Galileo developments) RIMS New Generation breadboard
As the current system architecture is under initial assessment and the related standards (ICAO SBAS L5, Galileo ICD's) are not yet finalized, it is basic driver to develop also the RIMS NG in a gradual step approach, ensuring that design or interface changes can be incorporated always in the next step of the development.
Therefore major drivers for the RIMS NG breadboard development are:
- Early availability to support MRS related experimentation in SPEED
- Modular and reconfigurable design of the RIMS NG BB
- Stepwise upgrade capability from breadboard over prototype to operational (certifiable) receiver (according to DAL C)
Concerning RIMS NG Breadboard, the most important topic is the necessary support of multi-constellation (GPS, Galileo) and their related frequencies as requested through the MRS regional navigation system architecture.
HISTB / HISTB 2
The SBAS and their associated ground infrastructure will exist and be operated at least until 2025-2030 since, as a key mission objective, the current augmentation services has to be maintained for those legacy Users equipped with mono frequency SBAS/GPS receivers at least until end of life of their equipment (typically 15 to 20 years).
Yet, over this period, the SBAS will have to evolve to account for GPS modernisation, advent of new constellations like the European Galileo, new aeronautical standards, as well as several further reasons like obsolescence of ground infrastructure elements.
Within the European GNSS Evolution Program (EGEP) the various evolution perspectives have been explored in more depth via several activities split into several test beds and accompanying EGNOS V3 during its phases A and B.
As one of several test beds, the High Integrity System Test Bed (HISTB) enables to run the experiments dealing with High Integrity performances for the aeronautical domain.
Within the first phase of the HISTB experiments have been conducted to demonstrate the advantages of a dual-frequency service as well as usage of message type 28 (orbit error covariance matrix broadcast) and provide evidence for achievable accuracy, availability, integrity, and continuity performances.
The second phase of the test bed - called HISTB2 - focused on the CS algorithms extension towards a dual-frequency multi-constellation GPS/Galileo service. Also, usage of mixed signals like L1/L2C and L1/L5 has been considered.