Post on 03-Apr-2018
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Update on
Ground based RegionalAugmentation System (GRAS)
Keith McPherson, Manager GNSS
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GRAS Definition
A system providing GNSS augmentation service by which the
user receives information directly from ground-based
transmitters, allowing continuous reception of the service over alarge geographical are(200Nm+). The ground components may
be interconnected in a network
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Rationale behind GRAS Availability of (D)GNSS is paramount for Air Traffic Management(ATM) development
Impact on both Navigation, Surveillance and Communications
Availability must be from gate-to-gate
Minimum of new systems for CNS cost efficiency
Value added service to CNS/ATM improved business cases
Available for all user groups at reasonable costs
High latitudes
National and/or Regional sovereign control of the service delivery is vital
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Aircraft GNSS integrity feed
GNSS Receiver
GPS/GLONASS/GALILEO
Navigation datalink Communications datalink
GRAS ADS-B Service
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Alternative Augmentation
Ground based Regional Augmentation System
Key BenefitsEnroute navigation over entire continent
Non-Precision Approaches, Approaches with vertical guidance
No single point of failure for whole system
Relatively inexpensive compared to US and Europeanaugmentation systems
Expected potential to further reduce current navigation aids
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GRAS usage En-route
APV I/II CAT I
A-SMGCS/ Surface movement
ADS-B Surveillance
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GRAS Concept
GPS Constellation
GRS GMSSatcom orTerrestrial
Links
Satcom orTerrestrial
LinksGVS
L
L
L
VHF
Users
GRAS Master Station processes GRS data
determines GPScorrections & integritystatus
generates SBASmessages
GRAS Ref. Stn
collects GPSmeas. & data
formats/sendsdata to GMS
GRAS VHF StnReceives &
verifies SBAS
messages
converts to GBAS
..format
broadcasts GRAS
messages at VHF
User Equip.
receives GPS
& GRAS datacomputes
SARPs-based
nav solution
GPS Constellation
GRS GMSSatcom orTerrestrial
Links
Satcom orTerrestrial
Links
Satcom orTerrestrial
Links
Satcom orTerrestrial
LinksGVS
L
L
L
VHF
Users
GRAS Master Station processes GRS data
determines GPScorrections & integritystatus
generates SBASmessages
GRAS Ref. Stn
collects GPSmeas. & data
formats/sendsdata to GMS
GRAS VHF StnReceives &
verifies SBAS
messages
converts to GBAS
..format
broadcasts GRAS
messages at VHF
User Equip.
receives GPS
& GRAS datacomputes
SARPs-based
nav solution
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Technical concept
GRASData Link
Automatic Ground
Station selection
GBAS
Format
VHF Data Links
Terrestrial Data Link
Large
AirportSmall
Airport
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Ground Reference Stations Broome
Carnavon
Perth Darwin
Alice Springs
GRAS Schematic
Master Control Stations Brisbane & Melbourne
Data Lines
(Operational Concept)
Not to Scale
VHF Transmitters Using current VHF voice transmission
sites
Connected by data-line to MasterControl Station
Ceduna
Thursday I
Mackay Canberra
Hobart
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VHF Sites Across Australia
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GRAS Architecture
Ground network
GRAS Broadcast
Interface to other
systems, e.g. other
GRAS stations or
SBAS/EGNOS
(external GRAS)
Remote service
monitoring etc.
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GRAS LATERAL ERROR
POINT COOK APPROACH RWY 35
RUN 35
-30
-20
-10
0
10
20
30
10
9.
69
9.
37
9.
03
8.
68
8.
34 8
7.
65
7.
3
6.
95
6.
59
6.
24
5.
89
5.
54
5.
18
4.
82
4.
46
4.
09
3.
72
3.
36 3
2.
65
2.
3
1.
94
1.
6
1.
26
0.
93
0.
6
0.
28
NM TO THRESHOLD
METRES
LATERAL ERROR
CAT 1 NSE LIMIT
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GRAS VERTICAL ERROR
POINT COOK APPROACH RWY 35
RUN 35
-20
-15
-10
-5
0
5
10
15
20
10
9.
69
9.
37
9.
03
8.
68
8.
34 8
7.
65
7.
3
6.
95
6.
59
6.
24
5.
89
5.
54
5.
18
4.
82
4.
46
4.
09
3.
72
3.
36 3
2.
65
2.
3
1.
94
1.
6
1.
26
0.
93
0.
6
0.
28
NM TO THRESHOLD
METRES
VERTICAL ERROR
CAT 1 NSE LIMIT
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VHF Cross-over Tests
elbourne
Cooma
Sydney
HobartTasmania
New South Wales
Albury
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VHF Cross-over Interference (None so far)
Slots A & H Equal Power Level Slots A & B Equal Power Level
Slots A & B Closer to Cooma
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20 August 2001
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10014074 10015074 10016074 10017074 10018074 10019074 10020074 10021074 10022074 10023074 10024074 10025074
dBm Melbourne
Cooma
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CNS/ATM Toolbox
Communications Navigation
Broadcast GRAS ADS-B
ATN
non-ATN
ADS-CPoint-to-point
ATC
Aircraft
Surface
ATC
Surveillance
FIS
TIS GNSS
RAIM Prediction
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GRAS
Navigat ion Survei l lance
En-route through APV to
Surface navigat ion
GNSS AUGMENTATION
ATC, aircr aft
and su rface vehicles
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GRAS in perspective
SBAS+ Wide Coverage
- Complexity
Institutional
GBAS
+ Local(23Nm)
- Dedicated landingSystem
Expensive
ABAS
+ Autonomous
- High End A/C
GRAS
+ Regional service
Step wise implementation
Added value service- Line of sight
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GRAS today
Sent to ICAO for standardisation (GNSSP) uses GBASmessage format with one change
Solid manufacturing support
Still a chance to control the development process
Service identical to GBAS standard.
GRAS supports PVT and is compatible to GNSSP PVT
Need for broader understanding and inclusion in regionalprograms as an alternative, regional solution
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ICAO Approval Status GRAS
Concept presented to ICAO
Air Navigation Commission tasked GNSS Panel to developSARPs 1999
Australia (Airservices) selected to develop SARPs
Standards and Recommended Practices (SARPs)
November 2000 - Concept of Operations developed
March 2001 - first draft of SARPs distributed
November 2001 - text mostly accepted by ICAO
October 2002 - final text
2002-2003 - validation process
March 2003 - approval expected by GNSS Panel
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ANY QUESTIONS ??
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