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The GPS Aided Geo Augmented Navigation or GPS and Geo Augmented Navigation system (GAGAN) is the SBAS implementation by the Indian government. | The GPS Aided Geo Augmented Navigation or GPS and Geo Augmented Navigation system (GAGAN) is the SBAS implementation by the Indian government. | ||
==GAGAN Introduction== | ==GAGAN Introduction== | ||
In August 2001 the [http://www. Airports Authority of India] and the [http://www. Indian Space Research Organization (ISRO)] signed a memorandum of understanding for jointly establishing the GAGAN system. | In August 2001 the [http://www. Airports Authority of India] and the [http://www. Indian Space Research Organization (ISRO)] signed a memorandum of understanding for jointly establishing the GAGAN system. | ||
It is being implemented in three phases: | It is being implemented in three phases:<ref name="GAGAN_COSPAR">''IRNSS and GAGAN status'' COSPAR Meeting, Montreal, July 2008<ref> | ||
# Technology Demonstration System (TDS). | # Technology Demonstration System (TDS). | ||
| Line 26: | Line 23: | ||
==GAGAN Architecture== | ==GAGAN Architecture== | ||
The main components of the GAGAN Architecture are: | <gallery widths="200px"> | ||
Image:gagan_overview.png|GAGAN overview.<ref name="GAGAN WIKI">[[Wikipedia:GPS_Aided_Geo_Augmented_Navigation|GPS Aided Geo Augmented Navigation on Wikipedia]]</ref> | |||
</gallery> | |||
The main components of the GAGAN Architecture are:<ref name="GAGAN_COSPAR"/> | |||
*Space segment: two operational GEO satellites, GSAT-8 & GSAT-9 satellites | *Space segment: two operational GEO satellites, GSAT-8 & GSAT-9 satellites | ||
| Line 41: | Line 42: | ||
GAGAN augments the GPS system with integrity and corrections to make the GPS system a trusted navigational aid. It will be built to support the integrity required for APV I phases of flight, and to meet the [[SBAS Fundamentals|performance requirements]] of international civil aviation regulatory bodies. | GAGAN augments the GPS system with integrity and corrections to make the GPS system a trusted navigational aid. It will be built to support the integrity required for APV I phases of flight, and to meet the [[SBAS Fundamentals|performance requirements]] of international civil aviation regulatory bodies. | ||
==Ionospheric issues== | |||
One of the main concerns about an SBAS implementation in India is the ionospheric behavior at these latitudes. The ionosphere near the geomagnetic equator has physical process and features that rarely, if ever, affect mid-latitudes. These include the Appleton geomagnetic anomaly, plasma bubbles, and scintillation. India is in fact iunder the geomagnetic equator. | |||
Current SBAS in the mid magnetic latitudes provide a precision guidance for the single frequency users [11]. The ionospheric phenomena mentioned above and typically found at the equatorial latitudes would significantly challenge SBAS approaches currently used in these mid magnetic latitudes for precision guidance. The peak large scale features could cause positioning inaccuracies to standard SBAS that may exceed the precision approach alert limits. Even when such extreme features are not present, the possibility of unobserved small scale features makes it difficult for an SBAS system to ensure integrity compatible with the precision approach alert limits. | |||
==GAGAN Development== | ==GAGAN Development== | ||
GAGAN is primarily meant for civil aviation | GAGAN is primarily meant for civil aviation. The goal is to provide navigation system to safety-to-life operations over the Indian airspace and in the adjoining area. Once GAGAN is operational, it should improve air safety over India and aircraft will be able to make precision approaches within the coverage area. There are 449 airports and airstrips in the country, but only 34 have instrument landing systems (ILSs) installed. <ref name="GAGAN WIKI"/> | ||
The Indian government states that it will use the experience of building the GAGAN system in the creation of an autonomous regional navigation system called the [[Work in Progress:IRNSS|Indian Regional Navigational Satellite System (IRNSS)]]. | |||
For the FOC Phase, new INRESs in Indore, Bhuj, Amritsar, Chennai, Nagpur, Lucknow and Visakhapatnam will be built, also a redundant Indian Master Control Centre (INMCC), an additional Indian Navigation Land Uplink Station (INLUS) and additional Communication links will be available. GAGAN is planned to get into operation by the year 2014.<ref name="GAGAN_COSPAR"/> | |||
Revision as of 08:42, 17 August 2011
| Other SBAS | |
|---|---|
| Title | GAGAN |
| Author(s) | GMV |
| Level | Basic |
| Year of Publication | 2011 |
The GPS Aided Geo Augmented Navigation or GPS and Geo Augmented Navigation system (GAGAN) is the SBAS implementation by the Indian government.
GAGAN Introduction
In August 2001 the Airports Authority of India and the Indian Space Research Organization (ISRO) signed a memorandum of understanding for jointly establishing the GAGAN system.
It is being implemented in three phases:Cite error: Closing </ref> missing for <ref> tag
GAGAN Architecture
![GAGAN overview.[1]](/navipedia/images/thumb/c/c1/Gagan_overview.png/182px-Gagan_overview.png)
GAGAN overview.[1]
![GAGAN overview.[1]](/navipedia/index.php?title=File:Gagan_overview.png)
The main components of the GAGAN Architecture are:[2]
- Space segment: two operational GEO satellites, GSAT-8 & GSAT-9 satellites
- Ground segment: On the ground, the GPS Data is received and processed in the 8 Indian Reference Stations (INRES), located at Delhi, Ahmedabad, Bangalore, Thiruvananthapuram, Kolkata, Guwahati, Port Blair and Jammu. The Indian Master Control Center (INMCC), located at Bangalore, processes the data from the multiple INRESs to determine the differential corrections. Information from the INMCC is sent to the Indian Land Uplink Station (INLUS) and uplinked along with the GEO navigation message to the GAGAN GEO satellite.
- User segment: GAGAN-enabled GPS Receivers, with the same technology as WAAS Receivers, capable to use the GAGAN Signal-in-Space (SIS). User equipment for civil aviation shall be certified against several standards (see article SBAS Standards).
Raytheon company was awarded in 2009 of the contract to build the complete GAGAN system.[3]
GAGAN Signals and Performances
The GAGAN GEO satellite will downlink navigation data via L1 and L5 WAAS signals, with Global Positioning System (GPS) type modulation. L1 and L5 WAAS signals were obtained from the United States Air Force and U.S Department of Defense on November 2001 and March 2005. [1]
GAGAN augments the GPS system with integrity and corrections to make the GPS system a trusted navigational aid. It will be built to support the integrity required for APV I phases of flight, and to meet the performance requirements of international civil aviation regulatory bodies.
Ionospheric issues
One of the main concerns about an SBAS implementation in India is the ionospheric behavior at these latitudes. The ionosphere near the geomagnetic equator has physical process and features that rarely, if ever, affect mid-latitudes. These include the Appleton geomagnetic anomaly, plasma bubbles, and scintillation. India is in fact iunder the geomagnetic equator.
Current SBAS in the mid magnetic latitudes provide a precision guidance for the single frequency users [11]. The ionospheric phenomena mentioned above and typically found at the equatorial latitudes would significantly challenge SBAS approaches currently used in these mid magnetic latitudes for precision guidance. The peak large scale features could cause positioning inaccuracies to standard SBAS that may exceed the precision approach alert limits. Even when such extreme features are not present, the possibility of unobserved small scale features makes it difficult for an SBAS system to ensure integrity compatible with the precision approach alert limits.
GAGAN Development
GAGAN is primarily meant for civil aviation. The goal is to provide navigation system to safety-to-life operations over the Indian airspace and in the adjoining area. Once GAGAN is operational, it should improve air safety over India and aircraft will be able to make precision approaches within the coverage area. There are 449 airports and airstrips in the country, but only 34 have instrument landing systems (ILSs) installed. [1]
The Indian government states that it will use the experience of building the GAGAN system in the creation of an autonomous regional navigation system called the Indian Regional Navigational Satellite System (IRNSS).
For the FOC Phase, new INRESs in Indore, Bhuj, Amritsar, Chennai, Nagpur, Lucknow and Visakhapatnam will be built, also a redundant Indian Master Control Centre (INMCC), an additional Indian Navigation Land Uplink Station (INLUS) and additional Communication links will be available. GAGAN is planned to get into operation by the year 2014.[2]
Notes
References
- ^ a b c GPS Aided Geo Augmented Navigation on Wikipedia
- ^ a b Cite error: Invalid
<ref>tag; no text was provided for refs namedGAGAN_COSPAR - ^ ISRO Extends Raytheon Contract for GAGAN GPS Augmentation System Inside GNSS News July 2009