Saturday 1 August 2015

GAGAN - GPS Aided Geo Augmented Navigation

Why in news?
ISRO has said it will provide navigational support to the country’s Railways through ‘GAGAN’ (GPS-aided geo-augmented navigation) system.

ISRO will provide satellite-generated information to the railways through space technology-based tools that will provide safety at unmanned level crossings

What does the news mean?

GAGAN was jointly developed by the ISRO and Airports Authority of India (AAI) with a view to assist aircraft in accurate landing.
The GAGAN signal is being broadcast through two Geostationary Earth Orbit (GEO) satellites — GSAT8 and GSAT10.
With the use of GAGAN software system, a tr ain would know the location of any unmanned level crossing and soon a a warning signal can be given.
As soon as the warning signal will be given, the train’s hooter will automatically start when it comes near an unmanned crossing.

Introduction to GAGAN

Satellite-based navigation has, over the years, become indispensable, with a multitude of both civilian and military uses. Vehicles, big and small, as well as aircraft and ships increasingly find their way using such navigation devices. People these days turn to map and location-based services on their mobile devices.
India moved closer to have its own satellite-based navigation when the Indian Space Research Organisation (ISRO) launched the first of seven satellites that will provide the country with an independent navigation satellite capability.
A navigation satellite system uses a cluster of spacecraft that regularly transmit signals. Suitably equipped receivers can then use that data to work out their exact position.

Why does India need a navigation satellite system independent of the U.S.-controlled GPS?
India now looks at having a navigation satellite system independent of the U.S.-controlled GPS (Global Positioning System). As of now, India relies on the GPS for the navigation service. Many countries in the world do not consider relying on US controlled navigation service a strategically sound option.
A military analysis of the U.S. invasion of Iraq showed that the U.S. had blocked GPS signals to Iraq and then inserted erroneous signals. It left Iraqi military blind beyond visual range. The Iraqi Army got misled and weapons missed their targets.
In the light of such a war-time strategy being employed, it is critically important for India to ensure autonomy and choice in strategic communications. Same points were also raised by the former Army Chief and Director-General of Military Intelligence; General S. Padmanabhan’s book ‘The Writing On The Wall – India Checkmates America 2017’.
With similar concerns, Europe, Russia, Japan and China are either having or evolving their own navigation services independent of the GPS.

The Indian Space Research Organisation too has been planning to evolve indigenous navigation service to provide enhanced and more precise navigation. This service is to be named Gagan(GPS Aided Geo Augmented Navigation).
To provide this service, India needs to launch a number of satellites. The first of this series, theIndian Regional Navigation Satellite System (IRNSS), was launched recently.
GAGAN is meant to be a regional satellite-based augmentation system (SBAS). This joint project by Airports Authority of India (AAI) and Indian Space Research Organization (ISRO) aims at providing a seamless navigation facility in the region, which is interoperable with other SBAS.
GAGAN will provide augmentation service for GPS over India, Bay of Bengal, South-East Asia, Middle East expanding upto Africa. GAGAN will be compatible and interoperable with other SBAS systems such as the Wide Area Augmentation System (WAAS) of USA, the European Geostationary Navigation Overlay Service (EGNOS) of European Union (EU) and the Multi-functional Satellite Augmentation System (MSAS) of Japan. It will fill the gap between the European EGNOS and the Japanese MSAS to provide seamless air navigation service across regional boundaries.
The AAI’s efforts towards implementation of operational SBAS can be viewed as the first step towards introduction of modern communication, navigation, surveillance/Air Traffic Management system over Indian airspace.
The project involves establishment of 15 Indian Reference Stations, three Indian Navigation Land Uplink Stations, three Indian Mission Control Centers and installation of all associated software and communication links. GAGAN is planned to get into operation by the year 2014.
It will be able to help pilots to navigate in the Indian airspace by an accuracy of 3 m. This will be helpful for landing aircraft in tough weather and terrain like Mangalore airport and Leh. The main advantages of the system are as follows.
  • Improved Efficiency/Economy due to direct routes and increased fuel savings
  • Approach with vertical guidance at all Runways
  • Significant cost savings due to withdrawal of ground aids
  • Reduced workload of Flight Crew and ATCOs
  • Improved Capacity through reduced aircraft separation
  • Higher Accuracy, Global Coverage
  • Improved Safety
  • Reduce the risk of Controlled Flight into Terrain (CFIT)
  • Enhanced Air-to-Air Surveillance:
  • Availability of MSAW facility (Min. Safe Altitude Warning)
  • Reduced Noise Pollution

Although primarily GAGAN is expected to provide satellite-based navigation for civil aviation across south and east Asia, and will provide India with the most accurate, flexible and efficient air navigation system deployed meant for civil aviation, it is also beneficial for other users.
Related Information
  • A satellite navigation or satnav system is a system of satellites that provide autonomous geo-spatial positioning with global coverage.


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