# Presentation: 306761

## 2nd Australian based CGSIC Meeting

**2****nd**** Australian based CGSIC Meeting**
**Ground based Regional Augmentation System (GRAS)**

**Keith McPherson, Manager GNSS**

## 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

##  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 **

## Aircraft GNSS integrity feed...

**GNSS Receiver**

- GPS/GLONASS/GALILEO

**Navigation datalink**

**Communications datalink**

- GRAS

- ADS-B Service

## 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

## GRAS usage

**En-route**
**APV I/II         CAT I**
**Surface movement guidance**
**ADS-B Surveillance**

## GRAS Concept

## Technical concept

- GRAS
- Data Link

- Automatic Ground
- Station selection

- GBAS
- Format

**VHF Data Links**

**Terrestrial Data Link**

**Large**

**Airport**

**Small**

**Airport**

## GRAS Schematic

**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**

## VHF Sites Across Australia

## GRAS Architecture

- Ground network

- GRAS Broadcast

*Interface to other systems, e.g. other GRAS stations or SBAS/EGNOS*
*(external GRAS)*

*Remote service monitoring etc.*

## Slide 12

## Slide 13

## VHF Cross-over Tests

## 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**

## Slide 16

##    GNSS AUGMENTATION

***Navigation***

***Surveillance***

***En-route through APV to ***
***Surface navigation***

***   ******GNSS AUGMENTATION***

***ATC, aircraft***
*** ******and surface vehicles***

## 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

## 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**

## 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 2000 - Concept of Operations developed**
**March 2001 - first draft of SARPs distributed**
**November 2001 - text mostly accepted by ICAO**
**October 2002 - final text agreed**
**2002-2003 - validation process**
**April 2003 - approval sought from GNSS Panel**

## ANY QUESTIONS ??

- Old Navigator

- New Navigator