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Page 1GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
GROUND BASED AUGMENTATION SYSTEMGROUND BASED AUGMENTATION SYSTEMSystem OverviewSystem OverviewChristophe DEHAYNAIN
Direction Générale de l’Aviation Civile FRANCE
GROUND BASED AUGMENTATION SYSTEMGROUND BASED AUGMENTATION SYSTEMSystem OverviewSystem OverviewChristophe DEHAYNAIN
Direction Générale de l’Aviation Civile FRANCE
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Page 2GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
GROUND BASED AUGMENTATION SYSTEMGROUND BASED AUGMENTATION SYSTEM
Presentation Presentation OverviewOverview
GROUND BASED AUGMENTATION SYSTEMGROUND BASED AUGMENTATION SYSTEM
Presentation Presentation OverviewOverview
• Why do we need an augmentation to GNSS ?
• Local Area Differential GNSS Principle
• GBAS Ground Segment
• GBAS Airborne Segment
• Conclusions
• Why do we need an augmentation to GNSS ?
• Local Area Differential GNSS Principle
• GBAS Ground Segment
• GBAS Airborne Segment
• Conclusions
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Page 3GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
GBAS ConceptGBAS Concept
SystemSystem Overview Overview
GBAS ConceptGBAS Concept
SystemSystem Overview Overview
• ICAO Name : GBAS for Ground Based Augmentation System
• Operational Coverage :– minimum : same as ILS– recommended : Omni directional (radius 23 NM) up
to FL 100 and down to 12 ft
• Data-Link Frequency range : 108 - 118 MHz (25 kHz spacing)
• Operational objective : – minimum : Category 1 approach– optional : 2 D navigation (Positioning Service)
• Localisation : Airport
• ICAO Name : GBAS for Ground Based Augmentation System
• Operational Coverage :– minimum : same as ILS– recommended : Omni directional (radius 23 NM) up
to FL 100 and down to 12 ft
• Data-Link Frequency range : 108 - 118 MHz (25 kHz spacing)
• Operational objective : – minimum : Category 1 approach– optional : 2 D navigation (Positioning Service)
• Localisation : Airport
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Page 4GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
GBAS OverviewGBAS Overview
Do not mistake Do not mistake GBASGBAS for : for :GBAS OverviewGBAS Overview
Do not mistake Do not mistake GBASGBAS for : for :
• DGPS, LADGPS : initial US generic names for GBAS concept
• SCAT1 or Special Category 1 : US RTCA standard defining a non-interoperable system for private use
• LAAS : Local Area Augmentation System : present US name for GBAS
• DGPS, LADGPS : initial US generic names for GBAS concept
• SCAT1 or Special Category 1 : US RTCA standard defining a non-interoperable system for private use
• LAAS : Local Area Augmentation System : present US name for GBAS
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Page 5GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
WHY GNSS NEEDS AN AUGMENTATION ?WHY GNSS NEEDS AN AUGMENTATION ?WHY GNSS NEEDS AN AUGMENTATION ?WHY GNSS NEEDS AN AUGMENTATION ?
PERFORMANCE CATEGORY IRequirements
ACCURACY (95%)
INTEGRITY
AVAILABILITY
H. 13 m V. 23 m V 4.0 mH 16.0 m
99.75 %
3,5.10-7/ approachTime to alarm 6 s
99% (RAIM)
GPS Only Civil Aviation
CONTINUITY OF SERVICE 10-4 / approach(10-5 / 15 s)
?
?
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Page 6GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
LOCAL AREA DIFFERENTIAL PRINCIPLELOCAL AREA DIFFERENTIAL PRINCIPLEI - Basic PrincipleI - Basic Principle
LOCAL AREA DIFFERENTIAL PRINCIPLELOCAL AREA DIFFERENTIAL PRINCIPLEI - Basic PrincipleI - Basic Principle
• Measurements made by two receivers are affected by the same errors as long as these two receivers are not too far from each other
• Measurements made by two receivers are affected by the same errors as long as these two receivers are not too far from each other
RX1
RX2
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Page 7GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
LOCAL AREA DIFFERENTIAL PRINCIPLELOCAL AREA DIFFERENTIAL PRINCIPLEII - Differential Correction CalculationII - Differential Correction Calculation
LOCAL AREA DIFFERENTIAL PRINCIPLELOCAL AREA DIFFERENTIAL PRINCIPLEII - Differential Correction CalculationII - Differential Correction Calculation
– The first receiver in a reference station can calculate these errors knowing its exact location (corrections calculated by the GBAS ground station)
– The second receiver (the user) will use these corrections to correct its own measurements and increase the accuracy of these measurements
– The first receiver in a reference station can calculate these errors knowing its exact location (corrections calculated by the GBAS ground station)
– The second receiver (the user) will use these corrections to correct its own measurements and increase the accuracy of these measurements
REFUSER
Known Reference Location
Calculated Range
Actual SV Position
Broadcast SV Position
CorrectionsCalculation Differential Message Broadcast
Measured Pseudoranges
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Page 8GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
GBAS ground segmentGBAS ground segmentI - BI - Basic architecture of a reference stationasic architecture of a reference station
GBAS ground segmentGBAS ground segmentI - BI - Basic architecture of a reference stationasic architecture of a reference station
Receiving Unit(up to 4 Reference Receivers)
Data Processing Unit
Data Broadcast Unit
Raw DataPR, ephem.,time
• Differential Corrections Calculation• Integrity Monitoring Functions• GBAS Messages Elaboration
Data processing for
broadcast
GPS/GLONASS Antennas Differential Message Broadcast Antenna
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Service Technique de la Navigation Aérienne
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Page 10GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
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Page 11GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
GBAS ground segmentGBAS ground segmentII - II - VHF Data Broadcast (VDB)VHF Data Broadcast (VDB)
GBAS ground segmentGBAS ground segmentII - II - VHF Data Broadcast (VDB)VHF Data Broadcast (VDB)
• GBAS VDB characteristics : – VHF NAV band (108 - 118 MHz), channel spacing 25 kHz
– D8PSK (Differential 8 States Phase Shift Keying) modulation
– 2 Hz update rate (Pseudorange Corrections)– 8 slots Time Division Multiple Access technique (16 per
second)– Horizontal Polarisation or Elliptical Polarisation
(Recommendation)– 50W ground transmitter power (Typically power for HPOL)– Omni-directional antenna– Coverage: 23 NM radius
• GBAS VDB characteristics : – VHF NAV band (108 - 118 MHz), channel spacing 25 kHz
– D8PSK (Differential 8 States Phase Shift Keying) modulation
– 2 Hz update rate (Pseudorange Corrections)– 8 slots Time Division Multiple Access technique (16 per
second)– Horizontal Polarisation or Elliptical Polarisation
(Recommendation)– 50W ground transmitter power (Typically power for HPOL)– Omni-directional antenna– Coverage: 23 NM radius
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Page 12GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
GBAS ground segmentGBAS ground segmentIII - III - VDB message contentVDB message content
GBAS ground segmentGBAS ground segmentIII - III - VDB message contentVDB message content
• The current SARPS require the transmission of three message types :– Differential Code Corrections and integrity Data– Reference Point and GBAS Data– Final Approach Path description
• The current SARPS require the transmission of three message types :– Differential Code Corrections and integrity Data– Reference Point and GBAS Data– Final Approach Path description
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Page 13GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
GBAS ground segmentGBAS ground segmentIV - GBAS Ground System ClassificationIV - GBAS Ground System Classification
GBAS ground segmentGBAS ground segmentIV - GBAS Ground System ClassificationIV - GBAS Ground System Classification
• The global performances of Ground System are linked to :– the Number of installed GNSS receivers (2 to 4)– The quality of the GNSS signal reception
• A Ground Accuracy Designator (GAD) will qualified the ground segment
• The global performances of Ground System are linked to :– the Number of installed GNSS receivers (2 to 4)– The quality of the GNSS signal reception
• A Ground Accuracy Designator (GAD) will qualified the ground segment
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Page 14GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
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Page 15GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
GBAS User segmentGBAS User segmentI-Basic operationsI-Basic operations
GBAS User segmentGBAS User segmentI-Basic operationsI-Basic operations
• GBAS will be basically used as an ILS (ILS Look-alike concept)
• RNAV 2D operations may be developed if the Ground System support the Positioning Service
• GBAS will be basically used as an ILS (ILS Look-alike concept)
• RNAV 2D operations may be developed if the Ground System support the Positioning Service
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Page 16GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
Service Technique de la Navigation Aérienne
GBAS User segmentGBAS User segmentII-Airborne EquipmentII-Airborne Equipment
GBAS User segmentGBAS User segmentII-Airborne EquipmentII-Airborne Equipment
• Multi-mode Receivers (MMR) and their associated GPS and VHF antennas will be used for GBAS approaches
• No hardware update is foreseen (Software only)
• Multi-mode Receivers (MMR) and their associated GPS and VHF antennas will be used for GBAS approaches
• No hardware update is foreseen (Software only)
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Page 17GBAS OVERVIEW GBAS OVERVIEW CAR/SAM ATN/GNSS SeminarCAR/SAM ATN/GNSS Seminar
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ConclusionsConclusionsConclusionsConclusions
• The GBAS system as standardised in ICAO Annex 10 is able to serve Cat-I operations. Advanced operations such as Cat-II/III or A-SMGCS are under consideration by ICAO GNSS Panel
• GBAS ground stations – are being built,– are considered in several implementation programmes in the
World
• GBAS airborne equipment– are being developed within Multi-Mode Receiver– are considered in several aircraft manufacturer programmes
• Standards Status– ICAO Standards (SARPS) are available– Other Standards (Doc 4444, Doc 8071, PANS OPS) are being
finalised– Industry Standards (MOPS) are being developed and will be soon
available
• The GBAS system as standardised in ICAO Annex 10 is able to serve Cat-I operations. Advanced operations such as Cat-II/III or A-SMGCS are under consideration by ICAO GNSS Panel
• GBAS ground stations – are being built,– are considered in several implementation programmes in the
World
• GBAS airborne equipment– are being developed within Multi-Mode Receiver– are considered in several aircraft manufacturer programmes
• Standards Status– ICAO Standards (SARPS) are available– Other Standards (Doc 4444, Doc 8071, PANS OPS) are being
finalised– Industry Standards (MOPS) are being developed and will be soon
available