1. METIS First Master Training & Seminar
Galileo/EGNOS and GPS & Augmented/Differential GPS
Prepared by
Mamadou Traore
GEMCO

2. European Navigation Satellites
GALILEO
It will achieve full independence through dedicated system under civil control
EGNOS
It provides an independently controlled civil complement to military GPS and GLONASS
METIS First Master Training & Seminar, Ifrane (Morocco),

3. GPS and GLONASS without augmentation
GPS/GLONASS Satellites
Like all other conventional systems, GPS and GLONASS
are subject to errors that can degrade the precision of
the systems.
These are:
Multipath
Ionospheric
Tropospheric
Satellite clock
Orbit
Receiver and Noise
- Selective availability, if any
User calculates
position
Neither GPS nor GLONASS can provide Continuity, Availability, Integrity and
Accuracy to be used as sole means of air navigation for all phases of flight.
So, augmentation is needed to meet operational requirements
METIS First Master Training & Seminar, Ifrane (Morocco),

4. GPS and GLONASS Augmentation 2- Applies correction to
GPS/GLONASS Satellites
1- User calculates
Position
2- Applies correction to
Calculated Position
1- Receiver calculates
Position
4- Transmits error
2- Compares to its own
Position
3- Calculates error
METIS First Master Training & Seminar, Ifrane (Morocco),

5. Benefits of Augmentation
GPS/GLONASS augmentation systems meet the operational
needs for all phases of flight by providing the four important
requirements:
Accuracy: how correct is the aircraft position estimate;
thanks to differential corrections
Integrity: the largest aircraft position error can reach
without detection; thanks to monitoring algorithms
Availability: how often can the aircraft use the systems and
have the desired Accuracy and Integrity; GEOs can be used as
additional ranging signals
Continuity: the probability that an operation once
commenced can be completed
METIS First Master Training & Seminar, Ifrane (Morocco),

6. Different Types of Augmentation
DGPS (many transmitting beacons, ionos. influence)
Aircraft-Based Augmentation System (ABAS)
- RAIM (Receiver Autonomous Integrity Monitoring)
- AAIM (Aircraft Autonomous Integrity Monitoring);
INS + Altimetry aiding
- FANS (Future Air Navigation System)
(low cost, needs many visible satellites)
Ground-Based Augmentation System (GBAS)
Space-Based Augmentation System (SBAS)
METIS First Master Training & Seminar, Ifrane (Morocco),

7. Aircraft-Based Augmentation System
ABAS achieves the 4 requirements of augmentation in
the following processing schemes:
- Integrity monitoring of the position solution
- redundant information (Receiver Autonomous Integrity Monitoring)
- additional onboard sensors (Aircraft Autonomous Integrity Monitoring)
- Continuity Aiding: using information of alternative sources
- Availability Aiding: for the position solution
- Accuracy Aiding: through estimation of errors
METIS First Master Training & Seminar, Ifrane (Morocco),

8. Ground-Based Augmentation Types Local Area Augmentation
Pseudo-Satellites
(Pseudolites)
Local Area Augmentation
System (LAAS)
Ground-Based Regional
Augmentation System (GRAS)
METIS First Master Training & Seminar, Ifrane (Morocco),

9. Simple Pseudolite Concept
GPS/GLONASS satellite
A Pseudolite works as a complete “ground-based satellite.
Pseudolite position is described in geographical terms while
GPS/GLONASS are in the orbital elements used by satellites
Satellite signal
direct to user
GPS User
Satellite signal
to Pseudolite
Pseudolite makes the following:
Measures the satellite signals
Creates a precisely timed GPS-like signal
Then transmits it over a data link to user
Pseudolite at a known point
METIS First Master Training & Seminar, Ifrane (Morocco),

10. Simple Synchrolite Concept
GPS/GLONASS satellites
Synchrolite works as an “electronic mirror ”:
Satellite signal
direct to user
Synchrolite
user
Satellite signals
to Synchrolite
Four reflected satellite signals
Coherent replica of a satellite signal “reflected” by synchrolite and synchronized to a received satellite signal.
A Synchrolite has much lesser latency than Pseudolite or any typical reference station
Synchrolite at a known position
METIS First Master Training & Seminar, Ifrane (Morocco),

11. GPS/GLONASS augmentation through Pseudolite
Availability: each additional Pseudolite ranging signal represents one less Satellite signal than required for basic navigation
Continuity: since satellites and Pseudolites are separate systems which can be managed by different organizations, the probabililty of a common failure is small
Accuracy: carefully located Pseudolites are available for aircraft in flight below the horizon.
Therefore, this will improve the vertical guidance for aircraft
Integrity: using additional ranging and satellite signals, Fault Detection and Fault Exclusion (FDE) can be done
METIS First Master Training & Seminar, Ifrane (Morocco),

12. Local Area Augmentation System
LAAS is a ground-based system which intended to provide the 4 operational requirements in order satisfy aircraft needs for precision approach, landing and surface navigation in very poor visibility. With 20 NM range.
The benefits of LAAS are multiple:
Remote Coverage: can augment WAAS in locations with low cost
Modified Approaches: to avoid Obstacles, Noises in sensitive area or crowed airspace
Multiple runway coverage: one LAAS can serve an entire Airport
Surface Navigation: can be used for ground navigation and taxiing
METIS First Master Training & Seminar, Ifrane (Morocco),

13. Ground-Based Regional Augmentation System
GRAS is a ground-based system which will broadcast information through a well developed local VHF network. Used to enhance the safety and efficiency of aircraft operations in all phases of flight (en-route, terminal and instrument approach with vertical guidance). With 200 NM range.
The benefits of GRAS are:
Operational for all phases of flight: en-route, terminal and instrument approach with vertical guidance operations
Deploy on Demand: a GRAS can be modified to provide service in specific area only
METIS First Master Training & Seminar, Ifrane (Morocco),

14. Different Types of SBAS
European Geostationary Navigation Overlay Service (EGNOS)
Wide Area Augmentation System (WAAS)
MTSAT Satellite Augmentation Service (MSAS)
GPS And Geo-Augmentation Navigation (GAGAN)
Satellite Navigation Augmentation Service (SNAS)
Military GPS Augmentation System (MGAS)
METIS First Master Training & Seminar, Ifrane (Morocco),

15. Space-Based Augmentation System Concept
GPS/GLONASS Satellites
GEO 4
Integrity &
Ranging+
corrections
Augmented
Navigation
Reference Stations 3 1
SBAS message
Master Station 2
METIS First Master Training & Seminar, Ifrane (Morocco),

16. EGNOS and Other Existing GNSS Systems
METIS First Master Training & Seminar, Ifrane (Morocco),

17. Difference between WAAS, EGNOS and MSAS
All 3 Space-Based Augmentation Systems are compatible to
each other; so, in principle, they are the same.
The main difference between DGPS and SBAS is the
calculation of the Total Electron Content (TEC) map for
ionospheric corrections
With DGPS, every single reference station, after comparing its
own position with the calculated position, transmits this
information on a certain band, as correction.
For SBAS, this is different. Here, the monitoring stations do not provide single
isolated corrections, but from all stations together a correction map for a wide
area. So, every receiver corrects its position by using this data.
That way, the accuracy is even better than with DGPS.
METIS First Master Training & Seminar, Ifrane (Morocco),

18. Highest Level of service supported
Types of SBAS Services
Types of SBAS Service
Corrections
Highest Level of service supported
GNSS satellite and GEO ranging
No correction
Through NPA
Basic differential corrections
Clock and ephemeris
Precise differential corrections
Clock, ephemeris and ionosphere
Through APV 2
METIS First Master Training & Seminar, Ifrane (Morocco),

19. Level of service from GNSS augmentation elements
Oceanic
en-route
Continental en-route
Terminal
Instrument Approach and Landing
ABAS
Suitable for navigation when fault detection and exclusion (FDE) is available
Suitable for navigation when RAIM is usable
Suitable for NPA when RAIM is available and another service is usable at alternate aerodrome
SBAS
Suitable for navigation
Suitable for NPA and APV depending on SBAS performance
GBAS
N/A
May be used as an input source for approved navigation systems
Suitable for NPA and PA CAT1 (potentially CAT2 and CAT3)
METIS First Master Training & Seminar, Ifrane (Morocco),

20. GNSS avionics standards for augmentation
Augmentation systems
Technical Standard Order (TSO)
Minimum Operational Performance Standards/Minimum Aviation Systems Performance Standards (MOPS/MASPS)
ABAS
TSO-C129 A Level 2 (en-route)
TSO-C129 A Level 1-3 (NPA)
RTCA / DO-208
EUROCAE ED – 72 A
SBAS
TSO-C145 A
TSO- C 146 A
RTCA / DO-229 C
EUROCAE (under development)
GBAS
Under development
RTCA / DO 245
RTCA / DO 246 B
RTCA / DO 253 A
EUROCAE ED - 95
METIS First Master Training & Seminar, Ifrane (Morocco),

21. How can SBAS augment GPS/GLONASS
GEO
Differential
Corrections
Use/Don’t
Use Message
GPS-Like
Signal
+ Accuracy
+ Availability
+ Continuity
+ Integrity
METIS First Master Training & Seminar, Ifrane (Morocco),

22. EGNOS GEO Satellites
METIS First Master Training & Seminar, Ifrane (Morocco),

23. EGNOS Architecture
METIS First Master Training & Seminar, Ifrane (Morocco),

24. EGNOS Extension Plan for MEDA
METIS First Master Training & Seminar, Ifrane (Morocco),

25. METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007

26. MULTIMODAL MISSION REQUIREMENTS
Civil Aviation:
Primary means of navigation down to Precision Approach with vertical Accuracy of 7.7 meters
Maritime:
Specified to be better than 4 meters in European Coastal waters
Expected performance around 1 meter horizontal accuracy
Land Applications:
Specified to be better than 4 meters in continental Europe
(Ref: EGNOS Mission Requirement Document, v 1.2)
METIS First Master Training & Seminar, Ifrane (Morocco),

27. GNSS Performance Requirements
METIS First Master Training & Seminar, Ifrane (Morocco),

28. ICAO Classification of Approaches
NPA
Non Precision Approaches
APV
Approaches with Vertical Guidance PA
Precision Approaches
RNAV
Lateral and vertical
guidance
Conventional
systems
Conventional
systems
RNAV
Lateral guidance
RNAV
Lateral and vertical guidance
APV.
BaroV NAV
APV I&II
VOR/DME
NDB
Localizer
ABAS
DME/DME BaroVNAV
ABAS
DME/DME
SBAS
GNSS Galileo
ILS
MLS
PAR
GBAS
METIS First Master Training & Seminar, Ifrane (Morocco),

29. Services provided by EGNOS
EGNOS system will provide the following services:
GEO Ranging (R-GEO): Transmission of GPS-like signals from 3 GEO : AOR-E, IOR and ARTEMIS. This will augment the number of navigation satellites available to the users.
GNSS Integrity Channel (GIC): Broadcasting of integrity information. This will increase the availability of GPS/GLONASS/EGNOS navigation service performance, mainly its accuracy, up to the NPA
Wide Area Differential (WAD): Broadcasting of differential corrections. This will increase the GPS/GLONASS/EGNOS service performance, mainly its accuracy, up to the level of PA
METIS First Master Training & Seminar, Ifrane (Morocco),

30. EGNOS Performance for Civil Aviation
Compliant for the En-Route Phases of Flight
Global availability better than % (assuming GIC/RAIM combination)
Compliant for the NPA Phase of Flight
Global availability better than % (assuming GIC/RAIM combination)
Provision of Precision Approach
Objective: to achieve APV-2 (VAL=20m) (Global Availability of 99%)
METIS First Master Training & Seminar, Ifrane (Morocco),

31. EGNOS Safety of Life Service (SoL)
Must stringent level of signal in space performance to all Communities of Safety of Life users over Europe
Accessible to any user equipped with a GPS/SBAS compatible receiver
Compliant with aviation APV-I intended to support applications in other SoL domains
Should be declared available following appropriate certification process
METIS First Master Training & Seminar, Ifrane (Morocco),

32. EGNOS Service Implementation Roadmap
Open Service
Readiness
Commercial Service Readiness
Safety Service
Readiness
Actions
2004
2005
2006
2007 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2
System Evolutions
Deliver system
Certify operations for SoL
Commercial service upgrade
Extend to Mediterranean
Services
Open Service
Commercial Service
Safety Of Life Service
METIS First Master Training & Seminar, Ifrane (Morocco),

33. GPS and GEO Augmented Navigation (GAGAN)
Spearheaded by ISRO and Airport Authority of India
Eight reference stations
The control centre and satellite uplink centre are located in Bangalore
Shall support NPA and Cat 1 landing
Should be operational in 2006
METIS First Master Training & Seminar, Ifrane (Morocco),

34. GALILEO Service Open Service Access
- Free to air, Mass Market, Simple positioning
- Commercial
- Encrypted, High accuracy, Guaranteed service
Safety of Life
- Unencrypted, Integrity certified
METIS First Master Training & Seminar, Ifrane (Morocco),

35. GALILEO Service (continued)
Search and Rescue
- near real-time, precise
Public Regulated
- Encrypted, Integrity, Continuous availability
METIS First Master Training & Seminar, Ifrane (Morocco),

36. EU Council Conclusions
The EGNOS programme should be placed under the control of the GALILEO Joint Undertaking
Inclusion of EGNOS management as part of the future GALILEO concession to be assessed
EGNOS should receive public funding from different sources
EGNOS should be certified for safety of life use (eg aviation) as soon as possible
Improvements should be made in order to meet evolving international standards
EGNOS extensions should be pursued to share its operation with other regions (eg MEDA)
METIS First Master Training & Seminar, Ifrane (Morocco),

37. Thank You! http://www.aui.ma/GNSS/metis/
METIS First Master Training & Seminar, Ifrane (Morocco),