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This paper is an update of the
GAGAN status presented at
NSP meeting on May 8-19,
2006 held at Brussels, Belgium
and also provides the future roadmap
of the project. GAGAN will provide
augmented information for satellite
navigation to the aircraft flying within
Indian Flight Information Regions
(FIRs), which consists of seven
boundaries. India is situated inthe
vicinity of equator. In the equatorial
region the ionospheric variations
are very predominant which affect
the GPS as well GEO signals. It
has therefore been decided to go for
unique regional Iono -Tropo model
over Indian airspace after collecting
TEC data over an extended period
of time from 20 TEC stations which
have been established for the purpose.
After analyzing the data for twenty
months, it has been observed that
seven more TEC stations are needed in
the equatorial anomaly region where
equatorial anomaly is very high, to
develop the model more accurate. |
| Implementation Timescale |
Technology Demonstration
Systems (TDS): This phase requires
implementation of a minimum
configuration system which would
demonstrate the capability of the
system to support up to precision
approaches over limited region of
the Indian airspace and will serve as
proof of concept. The performance
objective of this system is to meet
the ICAO SARPs requirements. The
TDS will consist of eight Indian
Reference Stations (INRES), an
Indian Mission Control Center
(INMCC), two Indian Land Uplink
System (INLUS), Space segment,
required communication links and
necessary software for navigation and
communication during the TDS phase.
The installation of the ground segment
has been completed and Preliminary
Site Acceptance Test (PSAT) has
been carried out with the help of
satellite emulator. In the scope of this
phase second frequency L5 is being
incorporated in both space and ground
segments. Initial Experimentation
Phase (IEP) has been merged with
TDS to make the system more usable
and now it is called TDS -Extended.
Final Operational Phase (FOP): during
this phase, the GAGAN program will
be matured. Extensive tests would be
carried out to establish the stability
of various elements of the system as
a whole. The system will be put in
extensive use for its evaluation with
respect to ICAO SARPs. Certification
and validation of the system will
be completed before declaring the
system operational. The FOP will
be completed by the year 2008 |
| Current status of GAGAN |
Infrastructure for installation of INRES
at Delhi, Kolkatta, Guwahati, Portblair,
Ahmedabad, Banglore, Jammu and
Trivanthapuram is in place. All eight
INRES equipment have been installed
and seven stations have been linked
through Optical Fiber Cable (OFC)
to INMCC for connectivity test. All
the station data are being recorded at
INMCC, Banglore. The installation
of GPS-TEC at all twenty stations has
been completed. Ionospheric data from
twenty TEC stations is being analyzed
by number of Indian universities
and R&D institutions involved in
ionospheric studies for the development
of an IONO-TROPO model that will
be suitable for Indian airspace. Based
on the results of extensive analysis, it
is proposed to install seven more GPSTEC
receiver in the mid region of India
due to Equatorial Indian Anomaly (EIA) where ionospheric variation is
very high. It is further observed that
scintillation is very active upto 60°
elevation based on thirty months data.
Infrastructure for INMCC and
INLUS at Banglore is in place and
installation of GAGAN equipment
have been completed. Infrastructure
for providing standby connectivity
through V-sat from all INRES to
INMCC is in progress, which will be
completed by December 2006. A geostationary
payload in C-Band and L1
and L5 frequencies will be carried by
GSAT-4 (fabricated and developed
by ISRO) placed at 82 ° E. GSAT-4 is
scheduled for launch by July 2007.
At present GAGAN ground segment
is under integration test and data
collection at INMCC Banglore has
begun. The possibility for hiring
of INMARSAT 4F1 navigation
transponder is being explored for
integration of GAGAN ground
system, to complete of Final Site
Acceptance Test (FSAT) and
conducting user level testing of
GAGAN Signal-In-Space (SIS) |
| Technology support
of development nd
maintenance of GAGAN |
ISRO in association with the AAI
will be developing the entire system
through all the stages of TDS, IEP and
FOP. ISRO will continue to provide
technology support, maintenance and
replenishment of the space segment of
the system, as and when required, to
maintain the robustness of the system. |
| Results |
The PSAT result of the GAGAN
TDS-Extended as follows |
| At present GAGAN
ground segment is
under integration
test and data
collection at
INMCC Bangalore |
• The TDS phase is to demonstrate
the expected vertical and horizontal
positional accuracies over 95%
of the time with the associated
Time-to-alarm (TTA) capability.
• Results were better than 7.6
meters accuracies in both vertical
and horizontal over 95% of
the time within the perimeter
of the reference stations.
• Using type 62 (test) message, the
TTA was better than 6.2 seconds
• Results were well within
the exit criteria of PSAT
• Perimeters of INRES sites too
exhibited good performance
The meeting is requested to take note
of the PSAT result of GAGAN. |
|
| January 2007 |
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Dr
Arjun Singh
Joint General Manager
Airports
Authority of
India |
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Dr S K Saraswati
Executive Director
(CNS-P)
Airports Authority of
India |
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Dr K Ramalingam
Chairman, Airports
Authority of
India |
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