Presentation on theme: "GPS and EGNOS in the EUR-SAM CORRIDOR"— Presentation transcript:
1GPS and EGNOS in the EUR-SAM CORRIDOR Lisardo Rodríguez RabanalDivisión de Navegación por SatéliteUnidad EGNOS Torrejón
2INDEX What is EGNOS? EGNOS ARCHITECTURE RNP FOR SBAS EGNOS COVERAGE AREAPERFORMANCES OVERVIEWEGNOS INTEGRITYCONCLUSIONS
3WHAT IS EGNOS?EGNOS (European Geostationary Navigation Overlay Service) is the European SBAS (Satellite Based Augmentation System) compliant with the OACI standard (Annex 10 of SARPS)EGNOS uses the GPS and GLONASS constellations as well as additional geostationary satellites which signals are collected by a network of ground stations for generating the EGNOS navigation message
4EGNOS ARCHITECTURE ( 2 INMARSAT III ( 2 INMARSAT III GPS GLONASS + 1 Artemis )+ 1 Artemis )Spatial SegmentGPSGPSGLONASSGLONASSUser SegmentRanging Integrity and Monitoring StationsNLESNLES(dos por GEO)RIMS1RIMS1RIMS2RIMS2RIMS 34RIMS … nGround SegmentEGNOS Network (EWAN)Red EGNOS (EWAN)MCC1MCC1MCC2MCC2MCC3MCC3MCC4MCC4Mission Control CentresPACFPACFASQFASQFDVPDVPSupport Segment
5RNP FOR SBAS (I)ACCURACY difference between the estimated position and the actual position.INTEGRITY is a measure of the trust which can be placed in the correctness of the information supplied by the system. Integrity includes the availability of the system to provide timely and valid warnings to the user (alerts) when the system must not be used for the intended operation.
6RNP FOR SBAS (II)CONTINUITY It is the probability that the system will function properly for the duration of the flight operation given that the system was functioning properly at the beginning of the operation.AVAILABILITY The portion of time during which the system is to be used for navigation during which reliable navigation information is presented to the crew, autopilot or other system managing the flight of the aircraft.
8EGNOS COVERAGE AREAEGNOS shall provide down to and including RNP 0.3 in the joint union of the ECAC Flight Information Regions (FIR).The shaded area comprises the footprint of all FIR of ECAC member States (including Canary Islands FIR) and the oceanic control areas of Reykjavik, Shanwick and Santa Maria.
11PERFORMANCES OVERVIEW The accuracy of GPS achieved in the Canary Islands is quite good.As the Canary Islands are located in the border of the EGNOS service area (landmasses of the ECAC) the EGNOS accuracy will be quite similar to the GPS one.The reason is that some satellites are discarded during the solution computation because of the lack of the ionospheric computation.
14EGNOS INTEGRITYSo the GPS/GLONASS performances in terms of accuracy could achieve the required performances for En-route, Terminal Area and Non-Precision Approach.However GPS as standalone system does not reach the performances in terms of integrity, continuity and availability.We need a measure of the trust which can be placed in the correctness of the navigation solution and timely alerts to the users when the navigation system must not be used for the intended operation.
15EGNOS INTEGRITYTo ensure that the GNSS position error is acceptable an alert limit is defined that represents the largest position error which results in a safe operation.At the same time EGNOS provides us the means to compute an estimation of the navigation error (Protection Level).Position errors greater than the alarm limit must be indicated to the crew, otherwise integrity has failed and flight safety is at risk.The GNSS integrity requirement is validated my means of measurements and simulations (due to the stringent probability 10-7) checking that the Navigation Error is bounded by the Protection Level.
16EGNOS INTEGRITY (SIMULATIONS) The next slides contain results obtained with the EGNOS End-To-End Simulator.A constellation of 27 GPS satellites + 1 EGNOS GEO has been configured.The EGNOS performances are evaluated in several airports in Canary IslandsThe results allow us to obtain an overview of the accuracy and integrity achieved with EGNOS in the Canary Islands.
19CONCLUSIONS Good GPS accuracy in the Canary Islands region “When you get a GPS navigation signal, how do you know you can trust it?”EGNOS will tell you whether you can trust the signal. It will tell you that you are at a particular spot with a high degree of certainty and definitely within an area enclosed by a circle with the spot at the centre. In effect, it will give you your position and say by how much it could be out.”
20CONCLUSIONSEn-route phases of flight can also take advantage of the EGNOS Integrity, Continuity and Availability benefitsOperational EGNOS (Operational Validation, ATC interface, Procedures Design)