1 2 nd Australian based CGSIC Meeting Ground based Regional Augmentation System (GRAS) Keith McPherson, Manager GNSS

2 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 a large geographical area (200Nm+). The ground components may be interconnected in a network

3 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

4 Aircraft GNSS integrity feed… GNSS Receiver GPS/GLONASS/GALILEO Navigation datalinkCommunications datalink GRAS ADS-B Service

5 Alternative Augmentation - GRAS Key Benefits Enroute navigation over entire continent Non-Precision Approaches Approaches with vertical guidance (APV-II) No single point of failure for whole system Relatively inexpensive compared to US and European augmentation systems Expected potential to further reduce current navigation aids

6 GRAS usage En-route APV I/II CAT I Surface movement guidance ADS-B Surveillance

7 GRAS Concept

8 Technical concept GRAS Data Link Automatic Ground Station selection GBAS Format VHF Data Links Terrestrial Data Link Large Airport Small Airport

9 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 Master Control Station –Ceduna –Thursday I –Mackay –Canberra –Hobart

10 VHF Sites Across Australia

11 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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14 VHF Cross-over Tests

15 VHF Cross-over Interference (None so far) Slots A & H Equal Power LevelSlots A & B Equal Power Level Slots A & B Closer to Cooma

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17 GRAS Navigation Surveillance En-route through APV to Surface navigation GNSS AUGMENTATION ATC, aircraft and surface vehicles

18 GRAS in perspective SBAS + Wide Coverage - Complexity Institutional GBAS + Local(23Nm) - Dedicated landing System Expensive ABAS + Autonomous - High End A/C GRAS + Regional service Step wise implementation Added value service - Line of sight

19 GRAS today Sent to ICAO for standardisation (GNSSP) uses GBAS message format with minor changes Solid manufacturing support RTCA and EUROCAE MOPS and MASPS to be completed Service identical to GBAS standard. GRAS supports PVT and is compatible to GNSSP PVT Need for broader understanding and inclusion in regional programs as an alternative, regional solution

20 ICAO Approval Status GRAS Concept presented to ICAO –Air Navigation Commission tasked GNSS Panel to develop SARPs 1999 –Australia (Airservices) selected to lead SARPs development Standards and Recommended Practices (SARPs) –November Concept of Operations developed –March first draft of SARPs distributed –November text mostly accepted by ICAO –October final text agreed – validation process –April approval sought from GNSS Panel

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