Indian Regional Navigation Satellite System

The Indian Regional Navigational Satellite System (IRNSS) 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, GPS, is not guaranteed in hostile situations.

Development

The government approved the project in May 2006, with the intention of the system to be completed and implemented by 2014. The first satellite of the proposed constellation, developed at a cost of Rs.1,600 crore (16 billion rupees), is expected to be launched in last quarter of 2011.

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. However reports came in Apr 2010 that India plans to start launching satellites by end of 2011 and six months periodic launches take place. It means the IRNSS optimally functional by 2014.

Description

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. These GEOs will be located at 34 East 83 East and 132 East longitude. The GSOs will be in orbits with a 24,000 km apogee and 250 km perigee inclined at 29 degrees. Two of the GSOs will cross the equator at 55 East and two at 111 East. 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.

According to a presentation by A Bhaskaranarayana to a meeting of COSPAR in Montreal on 15 July 2008, IRNSS signals will consist of a Special Positioning Service and a Precision Service. Both will be carried on L5 (1176.45 MHz) and S band (2492.08 MHz). The SPS signal will be modulated by a 1 MHz BPSK signal. The Precision Service will use BOC(5,2).

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.

See also

• GAGAN
• Global Navigation Satellite System
• GPS

References and footnotes

1. ^ SATNAV Industry Meet 2006. ISRO Space India Newsletter. April - September 2006 Issue.

2. http://www.rediff.com/news/2007/sep/27gps.htm

3. Launch of first satellite for Indian Regional Navigation Satellite system next year The Hindu - Apr 10, 2010