Indian Regional Navigational Satellite System
|Indian Regional Navigational Satellite System|
|Type||Satellite navigation system|
|Accuracy||Less than 20 m over the Indian Ocean region
Less than 10 m accuracy over mainland India
|Coverage||1,500–2,000 kilometres (930–1,240 mi) around Indian landmass|
|Project Cost||16 billion (US$240 million)|
The Indian Regional Navigational Satellite System (IRNSS) is an autonomous regional satellite navigation system being developed by the Indian Space Research Organisation (ISRO) which would be under complete control of the Indian government. The requirement of such a navigation system is driven by the fact that access to foreign government-controlled global navigation satellite systems is not guaranteed in hostile situations. The IRNSS would provide two services, with the Standard Positioning Service open for civilian use and the Restricted Service, encrypted one, for authorised users (military).
As part of the project, ISRO opened a new satellite navigation center within the campus of ISRO Deep Space Network (DSN) at Byalalu near Bangalore in Karnataka on 28 May 2013. A network of 21 ranging stations located across the country will provide data for the orbit determination of the satellites and monitoring of the navigation signal.
A goal of complete Indian control has been stated, with the space segment, ground segment and user receivers all being built in India. Its location in low latitudes facilitates a coverage with low-inclination satellites. Three satellites will be in geostationary orbit over the Indian Ocean. Missile targeting could be an important military application for the constellation.
The total cost of the project is expected to be 1420 crore (US$217 million), with the cost of the ground segment being 300 crore (US$46 million) and each satellites costing 125 crore (US$19 million).
In April 2010, it was reported that India plans to start launching satellites by the end of 2011, at a rate of one satellite every six months. This would have made the IRNSS functional by 2015. India also launched 3 new satellites into space to supplement this.
IRNSS-1A, the first of the seven satellites of the IRNSS constellation, was built at ISRO Satellite Centre, Bangalore, costing 125 crore (US$19 million). It has a lift-off mass of 1380 kg, and carries a navigation payload and a C-band ranging transponder, which operates in L5 band (1176.45 MHz) and S band (2492.028 MHz). An optimised I-1K bus structure with a power handling capability of around 1600 watts is used and is designed for a ten-year mission. The satellite was launched on-board PSLV-C22 on 1 July 2013 from the Satish Dhawan Space Centre at Sriharikota, while the full constellation is planned to be placed in orbit by 2015.
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 located in geostationary orbit at 32.5° East, 83° East, and 131.5° East longitude. Two of the GSOs will cross the equator at 55° East and two at 111.75° East.[dead link] 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.
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 10 meters throughout Indian landmass and better than 20 meters in the Indian Ocean as well as a region extending approximately 1,500 km around India.
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.
- Global Navigation Satellite System
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