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GPS-aided GEO augmented navigation

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TheGPS-aided GEO augmented navigation(GAGAN) is an implementation of a regionalsatellite-based augmentation system(SBAS) by theGovernment of India.[2]It is a system to improve the accuracy of aGNSS receiverby providing reference signals.[3]TheAirports Authority of India(AAI)'s efforts towards implementation of operational SBAS can be viewed as the first step towards introduction of moderncommunication, navigation and surveillance/air traffic managementsystem over the Indianairspace.[4]

GAGAN
GPS-aided GEO augmented navigation
TypeRegionalsatellite-based augmentation system
DevelopersIndian Space Research Organisation(ISRO)
Airports Authority of India(AAI)
Accuracy1.5 m or 4 ft 11 in (horizontal),
2.5 m or 8 ft 2 in (vertical)
Launched2001
Orbital radius26,600 km (approx)
Max operational life15 years
Fully operational by2013–14[1]
Project cost₹774crore(US$93 million)

The project has established 15 Indian Reference Stations (INRES), 2 Indian Master Control Centre (INMCC) and 3 Indian Land Uplink Station (INLUS) and installation of all associated software and communication links.[5]It will be able to help pilots to navigate in the Indian airspace by an accuracy of 3 m (9.8 ft) and will be helpful for landing aircraft in marginal weather and difficult approaches likeMangalore InternationalandKushok Bakula Rimpocheeairports.[6]

Implementation

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The₹774crore(US$93 million) project was deployed in three phases through 2008 by theAirports Authority of Indiawith the help of theIndian Space Research Organisation's (ISRO) technology and space support.[7]The goal is to provide navigation system for all phases of flight over the Indian airspace and in the adjoining area. It is applicable to safety-to-life operations, and meets the performance requirements of international civil aviation regulatory bodies.[8]

The space component became available after the launch of the GAGAN payload on theGSAT-8communication satellite, which was successfully launched. This payload was also part of theGSAT-4satellite that was lost when theGeosynchronous Satellite Launch Vehicle(GSLV) failed during launch in April 2010. A final system acceptance test was conducted during June 2012 followed by system certification during July 2013.[7]

All aircraft being registered in India after 1 July 2021 are mandated to be outfitted with GAGAN equipment.[9]The first aircraft to land using GAGAN system was anATR-72aircraft ofIndiGo.The landing was carried out 29 April 2022 inKishangarh Airport,Rajasthan.[10]

In 2024, reports suggested that all the new aircraft that were ordered byAir Indiaand IndiGo will be equipped with GAGAN systems whereas many of the turboprop aircraft in India like ATR-72 andDe Havilland Canada Dash 8.The GAGAN systems will be primarily operationalised in smaller airports lackinginstrument landing system(ILS) whereas larger airports with ILS will keep it as a backup option in case of non availability of such infrastructures.[11]

Technology demonstration

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The first phase of the system was the GAGAN-TDS (Technology Demonstration System). TDS was successfully completed during 2007 by installing eight Indian Reference Stations (INRESs) at eightIndian airportsand linked to the Master Control Centre (MCC) located nearBengaluru.Preliminary system acceptance testing has been successfully completed in December 2010.[7]Theground segmentfor GAGAN, which has been put up by the Raytheon, has fifteen reference stations scattered across the country. Two mission control centres, along with associated uplink stations, have been set up atKundalahalliin Bengaluru. One more control centre and uplink station were expected to be established at Bengaluru and Delhi. As a part of the programme, a network of eighteen total electron content (TEC) monitoring stations were installed at various locations in India to study and analyse the behaviour of theionosphereover the Indian region. The FSAT (Final System Acceptance Test) for GAGAN-TDS was completed on 14-15th August, 2007 using the signal-in-space (SIS) fromINMARSAT-4 F1.[12]

GAGAN's TDS signal in space provides a 3 m (9.8 ft) accuracy as against the requirement of 7.6 m (25 ft). Flight inspection of GAGAN signal is being carried out atCalicut International,Rajiv Gandhi International,Dr. Babasaheb Ambedkar InternationalandKempegowda Internationalairports and the results have been satisfactory so far.[when?]

Study of Ionosphere

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One essential component of the GAGAN project is the study of the ionospheric behaviour over the Indian region. This has been specially taken up in view of the uncertain nature of the behaviour of the ionosphere in the region. The ion content in the airspace increases with the increase of solar activities and peaks at around 2 pmIST.The study will lead to the optimisation of the algorithms for the ionospheric corrections in the region.[13]

To study the ionospheric behaviour more effectively over entire Indian airspace, Indian universities and research and development labs, which are involved in the development of regional based ionotropic model for GAGAN, have suggested nine more TEC stations.[4]

According to a report, however, told the problems faced due to this can be eliminated by using "dual-frequency multi-constellation (DFMC) GAGAN approach".[13]

Operational structure

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To begin implementing a satellite-based augmentation system over the Indian airspace,Wide Area Augmentation System(WAAS) codes for L1 frequency and L5 frequency were obtained from theUnited States Air Forceand theUnited States Department of Defensein November 2001 and March 2005.[4]United States defence contractorRaytheonhas taken part in the project to establish the required systems. The system will uses:[6]

  1. 15 Indian Reference Stations (INRES) located inDelhi,Ahmedabad,Bengaluru,Thiruvananthapuram,Kolkata,Guwahati,Port Blair,Jammu,Gaya,Jaisalmer,Nagpur,Dibrugarh,Bhubaneswar,PorbandarandGoa.
  2. 2 Indian Master Control Centre (INMCC) at Bengaluru.
  3. 3 Indian Land Uplink Station (INLUS); two in Bengaluru and one in Delhi.

Satellites

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There are two operational satellites excluding one as a backup[8][14]

  • GSAT-8is an Indian geostationary satellites, which was successfully launched usingAriane 5on 21 May 2011 and is positioned in geosynchronous orbit at 55 degrees E longitude.
  • GSAT-10is envisaged to augment the growing need of Ku and C-band transponders and carries 12 Ku Band, 12 C Band and 12 Extended C Band transponders and a GAGAN payload. The spacecraft employs the standard I-3K structure with power handling capability of around 6 kW with a lift off mass of 3,400 kg (7,500 lb). GSAT-10 was successfully launched byAriane 5on 29 September 2012.[7]
  • GSAT-15carries 24 Ku band transponders with India coverage beam and a GAGAN payload. It was successfully launched on 10 November 2015, 21:34:07 UTC, completing the constellation. This satellite is used as a spare and will be used in emergency scenarios.

Technology Integration

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GAGAN is now in operational phase and is compatible with other SBAS systems such as theWide Area Augmentation System(WAAS), theEuropean Geostationary Navigation Overlay Service(EGNOS) and theMTSAT Satellite Augmentation System(MSAS) and will provide seamless air navigation service across regional boundaries.[15]While the ground segment consists of fifteen reference stations and a master control centre, which will have sub systems such as data communication network,SBAScorrection and verification system, operations and maintenance system, performance monitoring display and payload simulator, Indian land uplinking stations will have dish antenna assembly. The space segment will consist of one geo-navigation transponder.

Effective flight-management system

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A GAGAN-basedflight management systemwill be able to save time and money of operators by controlling climb, descent, and engine performance profiles. The utilization of operator-preferred trajectories will increase, leading to increased efficiency and flexibility from the FMS. It will enhance access to airports and airspace in any weather conditions and enhance compliance with environmental and obstacle clearance requirements. By establishing more exact terminal area procedures with parallel routes and environmentally optimized airspace corridors, it will also improve reliability and decrease delays.[citation needed]

  • GAGAN will increase safety by using a three-dimensional approach operation with course guidance to the runway, which will reduce the risk of controlled flight into terrain i.e., an accident whereby an airworthy aircraft, under pilot control, inadvertently flies into terrain, an obstacle, or water.[10]
  • GAGAN will also offer high position accuracies over a wide geographical area like the Indian airspace. These positions accuracies will be simultaneously available to 80 civilian and more than 200 non-civilian airports and airfields and will facilitate an increase in the number of airports to 500 as planned. These position accuracies can be further enhanced with ground-based, augmentation system.

Developments

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The first GAGAN transmitter was integrated into the GSAT-4geostationarysatellite, and had a goal of being operational in 2008.[16][17]Following a series of delays,GSAT-4was launched on 15 April 2010, however it failed to reach orbit after the third stage of theGeosynchronous Satellite Launch VehicleMk.II that was carrying it malfunctioned.[18]

In 2009,Raytheonhad won an $82 million contract. It was mainly dedicated to modernise Indian air navigation system.[19]The vice president of Command and Control Systems, Raytheon Network Centric Systems, Andy Zogg commented:

GAGAN will be the world's most advanced air navigation system and further reinforces India's leadership in the forefront of air navigation. GAGAN will greatly improve safety, reduce congestion and enhance communications to meet India's growing air traffic management needs[19]

In 2012, theDefence Research and Development Organisation(DRDO) received a "miniaturised version" of the device with all the features fromGlobal Positioning Systems(GPS) andglobal navigation satellite systems(GNSS). The module weighing just 17 g (0.60 oz), can be used in multiple platforms ranging from aircraft (e.g. winged or rotor-craft) to small boats, ships. Reportedly, it can also assist "survey applications". It is a cost-efficient device and can be of "tremendous" civilian use. The navigation output is composed of GPS,GLONASSand GPS+GLONASS position, speed and time data. According to a statement released by the DRDO, G3oM is a state-of-the-art technology receiver, integrating Indian GAGAN as well as both global positioning system and GLONASS systems.[20]

According to Deccan chronicle:

G. Satheesh Reddy,associate director of the city-basedResearch Centre Imarat,said the product is bringing about a quantum leap in the area of GNSS technology and has paved the way for highly miniaturised GNSS systems for the future.[20]

On 30 December 2012, the Directorate General of Civil Aviation (DGCA), India provisionally certified the GPS-aided geo-augmented navigation (GAGAN) system to RNP0.1 (required navigation performance, 0.1nautical miles[0.19 km; 0.12 mi]) service level. The certification enabled aircraft fitted with SBAS equipment to use GAGAN signal in space for navigation purposes.[21]

Indian regional navigation satellite system (NAVIC)

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Main article:Indian Regional Navigation Satellite System

The Indian government has stated that it intends to use the experience of creating the GAGAN system to enable the creation of an autonomous regional navigation system called theIndianRegionalNavigationSatelliteSystem(IRNSS), operationally known asNavIC(acronym forNavigation withIndianConstellation).[22]

IRNSS-1 Indian regional navigational satellite system (IRNSS)-1, the first of the seven satellites of theIndian Regional Navigation Satellite Systemconstellation, carries a navigation payload and a C-band ranging transponder. The spacecraft employs an optimised I-1K structure with a power handling capability of around 1660W and a lift off mass of 1,425 kg (3,142 lb), and is designed for a nominal mission life of 10 years. The first satellite of IRNSS constellation was launched onboardPolar Satellite Launch Vehicle(PSLV) (C22) on 1 July 2012. While the full constellation was planned to be realised during 2014 time frame, launch of subsequent satellites was delayed.[citation needed]

Currently all seven satellites are in orbit but in 2017 it was announced that all threerubidiumbasedatomic clockson boardIRNSS-1Ahad failed, mirroring similar failures in theGalileoconstellation. The first failure occurred in July 2016, following which two other clocks also failed. This rendered the satellite somewhat redundant and required replacement. Although the satellite still performs other functions, the data is coarse, and thus cannot be used for accurate measurements. ISRO plans to replace it with IRNSS-1H in July or August 2017.

Two more clocks in the navigational system had started showing signs of abnormality, thereby taking the total number of failed clocks to five.

As a precaution to extend the operational life of navigation satellite, ISRO is running only onerubidium atomic clockinstead of two in the remaining six satellites. Each satellite has three clocks, therefore a total of 27 clocks for all satellites in the system (including standby satellites). The clocks of both IRNSS and GALILEO were supplied by SpectraTime. ISRO replaced the atomic clocks in two standby NavIC satellites. The setback comes at a time when IRNSS is yet to start commercial operations.

Applications

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Karnataka Forest Department has used GAGAN to build a new, accurate and publicly available satellite based database of its forestlands. This is a followup to theSupreme Courtdirective to states to update and put up their respective forest maps. Thegeospatialdatabase of forestlands pilot has used data from theCartosat-2satellite. The maps are meant to rid authorities of ambiguities related to forest boundaries and give clarity to forest administrators, revenue officials as also the public, according to R.K. Srivastava, chief conservator of forests (headquarters).[23]

TheIndian National Centre for Ocean Information Services(INCOIS) along with AAI has launched a new satellite-based GEMINI (Gagan Enabled Mariner's Instrument for Navigation and Information) system that will alert deep-sea fishermen of upcoming disasters. The GEMINI app on the cellphone decodes the signals from GEMINI device and alerts the user on imminent threats like cyclones, high waves, strong winds along with PFZ and search and rescue mission.

Various Indian manufactured missiles including theBrahMoswill use GAGAN for guidance.[24]

See also

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References

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  1. ^"Soon, safety in the sky as GPS-aided Gagan set to take off",The Times of India,23 January 2012,archivedfrom the original on 8 January 2014
  2. ^Singh, Amit (12 January 2019)."Ensuring safety and reliabity through indigenous satellite navigation system GAGAN".Times of India Blog.Retrieved7 May2019.
  3. ^"India Approves Gagan System".Magazine article.Asian Surveying and Mapping. 15 September 2008. Archived fromthe originalon 19 May 2009.Retrieved5 May2009.
  4. ^abcSingh, Arjun (28 August 2008)."GAGAN Update".mycoordinates.org.Archived fromthe originalon 28 August 2008.
  5. ^"GAGAN system ready for operations - The Hindu".The Hindu.11 January 2014.
  6. ^ab"GAGAN System".pib.gov.in.10 August 2024.Retrieved19 June2024.
  7. ^abcd"Satellite Navigation – GAGAN".ISRO website.Retrieved13 June2012.
  8. ^ab"GAGAN - GPS Aided GEO Augumented Navigation".www.ursc.gov.in.Retrieved19 June2024.
  9. ^"NavIC and GAGAN System Update"(PDF).28 September 2021.
  10. ^ab"IndiGo lands aircraft using indigenous navigation system GAGAN".The Economic Times.Retrieved19 June2024.
  11. ^"Small airports to be 1st to rely on GAGAN satnav for landings".The Times of India.16 June 2024.ISSN0971-8257.Retrieved19 June2024.
  12. ^"Coordinates: A resource on positioning, navigation and beyond » Blog Archive » GAGAN signal in space-validation and utilization".Retrieved19 June2024.
  13. ^ab"Small airports to be 1st to rely on GAGAN satnav for landings".The Times of India.16 June 2024.ISSN0971-8257.Retrieved25 June2024.
  14. ^"GSAT-15".www.isro.gov.in.Retrieved19 June2024.
  15. ^"GAGAN - Navipedia".gssc.esa.int.Retrieved22 August2019.
  16. ^ISRO, Raytheon complete tests for GAGAN satellite navigational system.Archived5 December 2006 at theWayback MachineIndia Defense Website. 20 June 2006.
  17. ^K.N. Suryanarayana Rao and S. Pal.The Indian SBAS System – GAGANArchived2 December 2006 at theWayback Machine.Abstract from the India-United States Conference on Space Science, Applications, and Commerce. June 2004.
  18. ^Subramanian, T. S. (15 April 2010)."India's indigenous GSLV D3 rocket fails in mission".The Hindu.Retrieved15 April2010.
  19. ^ab"Raytheon Wins $82M Air Navigation Contract From India".GovCon Wire.Retrieved29 September2012.
  20. ^ab17-gm device to guide missilesArchived5 September 2012 at theWayback MachineDeccan Chronicle.
  21. ^"GAGAN System Certified for RNP0.1 Operations".3 January 2014. Archived fromthe originalon 4 January 2014.Retrieved3 January2014.
  22. ^SATNAV Industry Meet 2006Archived31 March 2007 at theWayback Machine.ISRO Space India Newsletter. April – September 2006 Issue.
  23. ^"GAGAN kicks off new forest database".The Hindu.18 April 2015.ISSN0971-751X.Retrieved19 June2024.
  24. ^"Desi G3OM Makes BrahMos Smarter".The New Indian Express.9 July 2014.Retrieved2 December2021.

Further reading

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