The Indian Regional Navigational Satellite System
) is an autonomous regional satellite navigation system
being developed by Indian Space Research Organisation which would be under total control of Indian government
. The requirement of such a navigation system is driven by the fact that access to Global Navigation Satellite Systems is not guaranteed in hostile situations.
The government approved the project in May 2006, with the intention of the system to be completed and implemented by 2012. The first satellite of the proposed constellation, developed at a cost of Rupee
(16 billion rupees), is expected to be launched in 2009.
A goal of complete Indian control has been stated, with the space segment, ground segment and user receivers all being built in India.
It is unclear if recent agreements with the Russian government to restore their GLONASS system will supersede the IRNSS project or feed additional technical support to enable its completion.
The proposed system would consist of a constellation of seven satellites and a support ground segment. Three of the satellites in the constellation will be placed in geostationary orbit
and the remaining four in geosynchronous inclined orbit
of 29° relative to the equatorial plane. Such an arrangement would mean all seven satellites would have continuous radio visibility with Indian control stations. The satellite payloads would consist of atomic clocks and electronic equipment to generate the navigation signals. The navigation signals themselves would be transmitted in the S-band
frequency (2-4 GHz) and broadcast through a phased array antenna to maintain required coverage and signal strength. The satellites would weigh approximately 1,330 kg and their solar panels generate 1,400 watts.
The System is intended to provide an absolute position accuracy of better than 20 meters throughout India and within a region extending approximately 2,000 km around it.
The ground segment of IRNSS constellation would consist of a Master Control Center (MCC), ground stations to track and estimate the satellites' orbits and ensure the integrity of the network (IRIM), and additional ground stations to monitor the health of the satellites with the capability of issuing radio commands to the satellites (TT&C stations). The MCC would estimate and predict the position of all IRNSS satellites, calculate integrity, makes necessary ionospheric and clock corrections and run the navigation software. In pursuit of a highly independent system, an Indian standard time infrastructure would also be established.
References and Footnotes
1. SATNAV Industry Meet 2006
ISRO Space India Newsletter. April - September 2006 Issue.