GAGAN/GPS Aided Geo Augmented Navigation: Features

GAGAN/GPS Aided Geo Augmented Navigation: Features

Question: Union Minister of Civil Aviation. P. A. Gajapathi Raju recently launched the GAGAN/GPS Aided Geo Augmented Navigation system. Discuss they key features of this augmented navigation system.

- GAGAN is the first Indian SBAS (Satellite Based Augmentation System) certified for approach with Vertical Guidance operating within the ionosphere of the equatorial region

- It is the third SBAS after WAAS of the US and EGNOS of EU to be certified for en route operation since December 30th, 2013

- GAGAN is the joint effort of AAI and ISRO

- For aviation, GAGAN will support direct air routes, reduce fuel consumption and enhance safety

- GAGAN will also benefit agriculture, modes of transportation and public services such as defence and security agencies and disaster recovery management through search and rescue to locate the disaster zone with precision

- With effect from February 14th, 2014 GAGAN has been providing navigation signals launchd by GSAT-8 and GSAT-10 satellites launched by ISRO

- GAGAN has augmented the performance of GPS signals received over the Indian airspace

- Some of the areas where GAGAN will work include Civil Aviation, Marine Navigation, Train & Road Transport, Precision Farming, Search and Rescue (SAR) operations, Surveying and Mapping (Geodetic & Geodynamic), Mining and more.

- GAGAN is expected to provide navigation signals consistent with the International Civil Aviation Organisation/ICAO SARPs/Standards and Recommended Practices as set up by the Global Navigation Satellite System Panel

- GAGAN project involves setting up of SBAS comprising 15 Indian Reference Stations/INRES, 3 Indian Navigation Land Uplink Stations /INLUS, 3 Indian Mission Control Centres(INMCC), 3 geostationary navigation payload in C and L bands and associated software and communication links

About GPS

- Global Positioning System is a satellite navigation system which provides instant information about the position, velocity and time information anywhere on the globe and within the vicinity

- Baseline satellite constellation comprises 24 satellites positioned in 6 earth centred minutes

- Orbital period of GPS satellite is 50% of a sidereal day or 11 hours 58 minutes

- Nearly circular, equally spaced orbits around the equator at 60 degree separation within inclination of 55 degrees relative to the equator form the path of the GPS

How GAGAN Operates

- GAGAN is a Global Navigation Satellite System where data received is processed at widely dispersed INRES strategically located to ensure coverage over required service volume

- Data is forwarded to INMCC which processes data from multiple INRES to assess differential corrections and residual errors for monitored satellites and predetermined ionospheric grid point

- Information from INMCC is received by INLUS and uplinked alongside GEO Navigation message to GAGAN GEO Satellite

- GAGAN GEO satellite is associated with downlinking this data to users through L band ranging signal frequencies with GPS type modulation for enhancing accuracy, availability and data integrity

Benefits of GAGAN

Civil Aviation Sector

- Improved efficiency and fuel economy for the civil aviation sector

- Precision approach at all runways

- Cost savings due to withdrawal of ground aids

- Improved capacity through reduced aircraft separation and reduced workload of flight crews and ATCO

- Improved capacity through reduced aircraft separation and higher accuracy as well as international coverage

- Improved Flight Safety and Air to Air Surveillance

- Controlled Flight into Terrain and availability of MSAW facility(Minimum Safe Altitude Warning)

- Reduction of noise pollution

Non Civil Aviation Sector

- Marine Navigation
Road and Rail transport

- Precision farming

- Search and rescue operations

- Surveying and work of the scientific community

Facts and Stats

- India is the 4th country in the world to have SBAS

- Orbital radius of GAGAN is around 26,600 km

- GAGAN provides augmentation service for GPS across India, SE Asia and MENA

- GAGAN is also compatible and operable with other SBAS systems such as the following:

- Wide Area Augmentation System of the US

- European Geostationary Navigation Overlay Service of the EU

- MSAS or Multi Functioning Satellite Augmentation System of Japan

- It will close the gap between EGNOS and MSAS to provide services transcending regional boundaries
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