Indian Regional Navigation Satellite System (IRNSS) is an independent regional navigation satellite system.
It is designed to provide position accuracy better than 10m over India and the region extending about
1500 kms around India. It will provide an accurate real time Position, Navigation and Time (PNT) services to users on a variety of platforms with 24x7 service availability under all weather conditions.
The IRNSS system mainly consists of three components, namely, Space Segment (Constellation of Satellites & Signal–In–Space), Ground Segment and User Segment. IRNSS constellation consists of seven satellites. Three Satellites will be placed in the Geostationary Equatorial orbit (GEO at 34 deg East, 83 deg East & 131.5 deg East) and two satellites each will be placed in the Geosynchronous orbit (GSO) with equator crossing at 55 deg East and 111.5 deg East and an inclination of 29 deg. Two spare satellites are also planned to be realised. IRNSS will have two types of signals in L5 and S-band centre frequency, with the L band centre frequency being 1176.45 MHz and S-band centre frequency being 2492.028 MHz. Both L5 and S-band consist of two downlinks. IRNSS provides two basic services such as Standard Positioning Service (SPS) for common civilian users and Restricted Service (RS) for special authorised users.
The spacecraft configuration has been finalised and the satellites of the constellation are being configured identically with each spacecraft weighing 1425 kg. Efforts are on to productionise the standard subsystems. First flight model structure has been ready for assembly and integration. Clearance has been given for the fabrication of two more structures. Design reviews of major subsystems of IRNSS satellites like Spacecraft structure, Thermal control system, Propulsion system, Power System, Telemetry, Tracking and Command, Deployment mechanisms, Pyrotechnic devices, Composite elements, Check out and Integration, etc., have been completed. The spacecraft is basically configured with I-1K Bus to be compatible for launch onboard PSLV.
The navigation software for IRNSS is being indigenously developed at ISRO Satellite Centre. In house development of single channel SPS and RS dual frequency receiver to facilitate the testing of Navigation payload is under progress. Efforts are on to realise the IRNSS Signal Simulator. ISRO is collaborating with NPL to realise a space qualified Rubidium Atomic Frequency Standard.