GAGAN is India's Satellite-Based Augmentation System (SBAS) that improves the accuracy and integrity of GPS signals for civil aviation in India and surrounding areas. It consists of a network of Indian Navigation Reference Stations, two Indian Master Control Centers, and three Indian Navigation Land Uplink Stations. The stations monitor GPS and geostationary satellite signals, calculate corrections, and transmit the corrections to planes to improve positioning accuracy to within 0.1 nautical miles for non-precision approaches and 1.0 meters for precision approaches. When completed, GAGAN will provide reliable navigation for aviation and benefits like increased safety, reduced delays, and greater airspace capacity over India.

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2. GAGAN
(AN INDIAN EYE ON THE SKY)
SAAD BABAR ABBASI
GNSS-02
150511011
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4. CONTENTS
• BACKGROUND
• GNSS AUGMENTATION
• SBAS
• GBAS
• GAGAN
• ARCHITECTURE
• INRES
• INMCC
• INLUS
• PERFORMANCE
• BENEFITS
• REFERENCES
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5. BACKGROUND
• The GPS developed by the US has failed to meet the requirements of civil aviation
community
• The US$115 million project is being created in three phases through 2008 by
the Airport Authority of India with the help of the Indian Space Research
Organization's (ISRO) technology and space support
• 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
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6. GNSS AUGMENTATION
• Augmentation of a global navigation satellite system (GNSS) is a method of
improving the navigation system's attributes, such as accuracy, reliability, and
availability, through the integration of external information into the calculation
process
• GNSS augmentation is of two types
I. SBAS (satellite based augmentation system)
II. GBAS(ground based augmentation system)
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7. SBAS
• Satellite-based augmentation systems (SBAS), such as EGNOS, complement existing global
navigation satellite systems (GNSS). SBAS compensate for certain disadvantages of GNSS in
terms of accuracy, integrity, continuity and availability
• The SBAS concept is based on GNSS measurements by accurately-located reference stations
deployed across an entire continent
• The GNSS errors are then transferred to a computing center, which calculate differential
corrections and integrity messages
• SBAS messages are broadcast via geostationary satellites able to cover vast areas
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8. SBAS CURRENT SCENARIO
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9. SBAS (GAGAN)
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10. GBAS
• Each of the terms ground-based augmentation system (GBAS) and ground-based
regional augmentation system(GRAS) describe a system that supports
augmentation through the use of terrestrial radio messages.
• Ground based augmentation systems are commonly composed of one or more
accurately surveyed ground stations, which take measurements concerning the
GNSS, and one or more radio transmitters, which transmit the information directly
to the end user.
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11. GBAS
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12. GAGAN
(GPS AIDED GEO AUGMENTED NAVIGATION)
• The GAGAN system consists of a network of 15 Indian Navigation Reference Earth Stations
(INRES) that are precisely surveyed to compare the position determined from GPS satellite
signals against the location of the receiver
• The observed deltas are then be sent to 2 Indian Navigation Master Control Centers
(INMCC) where computer processing will extrapolate the data to generate correcting deltas
for GPS signals anywhere within the network
• These correcting deltas will be relayed via 3 Indian Navigation Land Uplink Stations (INLUS)
and geostationary satellites to civil aircraft so more precise fixes of their position can be
derived from GPS satellite signals
• INRES sites and INMCCs are connected using Optical Fiber Cable Data Communication
Network as well as VSAT link
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13. ARCHITECTURE
• GAGAN consists of two basic components the space segment and the ground
segment
• Space segment consists of
I. 3 GEO satellites (2 operational one to be launched)
II. GPS constellation
• Ground segment consists of
I. INRES (Indian reference stations)
II. INMCC (Indian master control stations)
III. INLUS (Indian navigation land earth uplink stations)
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14. ARCHITECTURE
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15. INRES
• The INRES collect measurement data and broadcast messages from all GPS
and GEO satellites in view and forward to Indian Mission Control Centre
(INMCC).
• Altogether 8 INRES Stations are established in India
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16. INMCC
• An Indian Master Control Centre (INMCC) is established at Kundalahalli, Bangalore.
• The measurement data collected every second from each of the INRES receiver
chains are transmitted in real time to the INMCC for correction and integrity
processing and generation of SBAS messages with the aid of the navigation
software resident.
• The INMCC comprises of various subsystems like Data Communication Subsystem
(DCSS), Correction and Verification Subsystem (C&VS), Operation and Maintenance
Subsystem (OMSS) and Service Monitoring Subsystem (SMS).
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17. INLUC
• The INLUS receives correction messages from the INMCC, format those messages
for GPS compatibility and transmit them to the GEO satellites for broadcast to user
platforms.
• The INLUS is collocated with INMCC at Bangalore. The INLUS also provides GEO
satellite ranging information and corrections to the GEO satellite clocks.
• Message formats and timing will be according to the functional and performance
specifications, which are derived from MOPS (Minimum Operation Performance
Standard).
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19. PERFORMANCE
• GAGAN provides a civil aeronautical navigation signal consistent with International
Civil Aviation Organization (ICAO) Standards and Recommended Practices (SARPs)
as established by the Global Navigation Satellite System (GNSS) Panel
• The GAGAN system provides non-precision approach (NPA) service accurate to
within the radius of 1/10th of a nautical mile (required navigation performance or
RNP-0.1) over the Indian FIR as well as precision approach) service of APV-1.0
(approach with Vertical guidance) over the Indian landmass on nominal days
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20. PERFORMANCE
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21. BENEFITS/APPLICATIONS
1. AVAITION
I. GAGAN enhances reliability and reduces delays to aircraft
II. GAGAN reduced workload of flight crew and Air Traffic Controllers.
III. It enhanced meteorological information
IV. It also reduced congestion
V. It enhanced safety, reduced delays and increased airport & airspace capacity
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22. BENEFITS/APPLICATIONS
2. CIVIL
I. Better accuracy, reliability, and availability through the integration of external information
II. Useful for surveying, fleet management, traffic control, health and rescue and other
countless applications
III. Better research and modelling of ionosphere
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23. REFERENCES
• www.google.com
• www.isro.gov
• www.insidegnss.com
• www.navipedia.net
• www.wikipedia.org
• ICAO International Standards and Recommended Practices, Annex 10 to the Convention pm
International Civil Aviation, Volume I Radio Navigation Aids, Section 3.7.1: Definitions
• 2.Mishra Pratap& EngePer, Global Positioning System, Signals, Measurements and
Performance (Ganga-Jamuna Press, Lincoln, Mass, USA), 2012, pp.-123-173
• 3.Parkinson Bradford W & SpilkerJames J, Global Positioning System: Theory and
Applications, Volume I, by (Jr. American Institute of Aeronautics and Astronautics Inc, USA),
2010, pp. 10-17, 478-483, 485-513.
• 4.KlobucharJ A, P H Doherty, M B El-Arini , Lejeune R, Dehel T, de Paula E R & Rodrigues F S,
Ionosphere Issues for a SBAS in the Equatorial Region, Ionosphere Effects Symposium,
Alexandria, Virginia, 7-9 May 2012.
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