ISRO to launch 1st satellite of Indian version of GPS constellation in December

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Excellent news for all Indians!!!!!

India to Launch 1st IRNSS Satellite by December​

The Indian Space Research Organisation says it is on track to launch the first satellite in the Indian Regional Navigation Satellite system by the end of the year. The entire constellation will be in place by 2012.

According to a presentation by A. Bhaskaranarayana to a meeting of the Committee on Space Research (COSPAR) in Montreal on 15 July 2008, IRNSS will consists of three satellites (called GEOs) on the geostationary arc above India and four (called GSOs) in two highly inclined quazi-zenith orbits.

The GEOs will be located at 34°E, 83°E and 132°E. 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°E and two at 111°E.

The system is designed to provide 20 metre accuracy over the Indian Ocean and 10 metres over the sub-continent.

The GEO satellites will have a 9.4 year lifespan. The GSOs will have a design life of 11 years.

ISRO will use its Polar Satellite Launch Vehicle to place the satellites in orbit.

The system will require a sophisticated ground segment. The space craft control centre will contain two telemetry uplink stations and a navigation centre. A timing centre, a laser ranging centre and 20 ranging and integrity monitoring stations will also be established. A data communications network will connect the entire system.

IRNSS signals will consist of a Special Positioning Service and a Precision Service. Both will be carried on L5 (1176.45 MHz) and S (2492.08 MHz). The SPS signal will be modulated by a 1 MHz BPSK signal. The Precision service will use BOC(5,2)

The ground segment will consist of multi-constellation receivers capable of simultaneously receiving both signals from all seven satellites while over Indian territory. It will also receive GPS signals augmented by the Gagan system.

India to Launch 1st IRNSS Satellite by December :: ASM

 

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Some background info on the IRNSS follows.......

 

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India heads for a regional navigation satellite system​

by, DR ARJUN SINGH AND DR S K SARASWATI

Indian Space Research Organisation has taken up a project called Indian Regional Navigation Satellite System for the establishment of an independent regional navigational infrastructure

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Indian Space Research Organisation (ISRO) has taken up a project called Indian Regional Navigation Satellite System (IRNSS) for the establishment of an independent regional navigational infrastructure. The system main objective is to provide high positional accuracy (comparable to the existing constellations) real time position, velocity and time for various users in the region. IRNSS services will be available on a 24x7x365 basis irrespective of the availability of other constellations over Indian airspace. The system leverages the technological competence of ISRO in satellite, ground and other critical technologies

Proposed IRNSS Architecture

The proposed architecture of the INRSS consists of space segment, ground segment and user segment. The space segment consists of three GEOs located at 34° E, 83° E and 132° E and four GSOs. The 4 N-GSOS will be placed in the orbit at an inclination angle of 29° with longitude crossing at 55° and 111° East. The ground segment consists of INRSS ranging and integrity monitoring which will be located at 20 places and most of them will be located in the airports along with GAGAN ground elements. IRNSS will have the two Master Control Stations (MCS), which may be co-located with GAGAN INMCC. The proposed INRSS architecture is shown in Fig. 1. The intended coverage area for IRNSS has been proposed to be over the Indian subcontinent and service area will be primarily on the Indian land mass and adjoining areas. The service area for IRNSS is specified as between longitude 40oE to 140o E and between latitude ± 40o. More specifically the coverage should include the Indian subcontinent plus about 1500 Km beyond the Indian geographical area. IRNSS system provides dual frequency (S & L5 band) usage with a targeted position accuracy of less than 10 meters within India. At present one down link in S-band and three down links in L5 band are planned. The system can be augmented with local area augmentation for higher accuracy.

The error budget of the proposed IRNSS is given below in Table 1.

The proposed IRNSS will be designed indigenously and launched from Indian soil through Polar Satellite Launch Vehicle (PSLV). The proposed satellite specifications are given below.

• Dry mass of the satellite ~ 600 kgs
• Power generation 1400 watts
• Fuel loading capacity ~ 785 kgs
• Accommodates navigation payload of weight 102 kgs and 375 watts of power

The snap shot of IRNSS GEOS & GSOS satellite locations are shown in Fig. 2.

IRNSS payload

It will provide signal generation on board and there will be two downlinks providing dual frequency operation with EIRP of 31.5 dBW at EOC. INRSS payload will have 3 Rubidium clocks and Navigation data up link will be through telemetry command link. The payload beam of GSOS will be steered to take care of the inclination.

IRNSS Ground Segment Functionality

The ground segment consists of MCC, INRSS Ranging and Integrity Monitoring (IRIM) Stations and IRNSS telemetry and command stations. The function of MCC is to estimate and predicts the ephemeris; calculate corrections for SV clock & maintain IRNSS time, Ionospheric corrections and Integrity. The function of IRNSS IRIM stations will be receiving the data from the GEOs and GSOs, transmit the data to MCC and one way ranging of the GEOs & GSOs in S band. The function of IRNSS telemetry and command stations will be to receive telemetry from the IRNSS constellation, Telecomm and the IRNSS constellation and navigation updates.

USER Segment

The user segment will consist of a specially designed inter operable dual frequency receiver, which may receive the data from other constellation of
navigation satellite. User segment receiver may be called as multi constellation receiver. The user receiver to get the required position accuracy will continuously track all the seven satellites of INRSS. The user receiver will have minimum G/T of -25 dB/K similar to GPS.

Conclusion

The INRSS is under planning stage and ISRO is the main agency to design and implement the entire infrastructure required for operation of the system. It has also to do certification and validation of the signal will be before declaring operational for the users.

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About the authors:

Dr Arjun Singh: Joint General Manager Airports Authority of India

Dr S K Saraswati: Executive Director (CNS-P), Airports Authority of India

 

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A ppt on IRNSS and GAGAN, by A. Bhaskaranarayana, Director SCP/FMO & Scientific Secretary, Indian Space Research Organisation.

Presentation to COSPAR Meeting, Montreal