IRNSS:
The Indian Regional Navigation Satellite System (IRNSS) is a state-of-the-art satellite navigation system owned and operated by the Government of India. It was meticulously developed by the renowned Indian Space Research Organization (ISRO) to provide precise navigation services over the expanse of India and its neighbouring countries. The system seamlessly transitioned into operational status with a constellation of seven active satellites perfectly positioned in their designated orbits. Researchers and scientists are privileged to dissect the intricate NavIC signals to conduct in-depth ionospheric studies and pioneer innovative algorithms for improved navigation accuracy. These signals encompass a Standard Positioning Service (SPS) and a Restricted Service (RS) transmitted through L5 (1176.45 MHz) and S-band (2492.028MHz) frequencies. Notably, three of the seven satellites majestically orbit the earth in the geostationary orbit (GEO), while the remaining four gracefully navigate in an inclined geosynchronous orbit (IGSO). In a bid to expand the system's global coverage, ISRO has presented a compelling plan to augment the satellite constellation by deploying twelve satellites in the Medium Earth Orbit (MEO).
The IRNSS system architecture mainly consists of:
Space Segment
Ground Segment
User Segment
SPACE SEGMENT:
The IRNSS space segment consists of seven satellites. These satellites are designed around an I-1K bus with a dry mass of 600 kg and a launch mass of 1425 kg. They have a power generation capability of 1600 W. Highly stable Rubidium Atomic Frequency Standards (RAFS) are used on board to generate navigation signals. IRNSS is an independent regional navigation satellite system being developed by India. It is designed to provide accurate position information service to users in India as well as the region extending up to 1500 km from its boundary, which is its primary service area. An Extended Service Area lies between the primary service area and the area enclosed by the rectangle from Latitude 30 deg South to 50 deg North, Longitude 30 deg East to 130 deg East. IRNSS will provide two types of services, namely, Standard Positioning Service (SPS) which is provided to all the users and Restricted Service (RS), which is an encrypted service provided only to the authorized users. The IRNSS System is expected to provide a position accuracy of better than 20 m in the primary service area.
GROUND SEGMENT:
The ground segment plays a crucial role in keeping the IRNSS constellation operational. This segment is
responsible for the maintenance and operation of the constellation. The ground segment consists of:
IRNSS Spacecraft Control Facility (IRSCF)
ISRO Navigation Centre (INC)
IRNSS Range and Integrity Monitoring Stations (IRIMS)
IRNSS Network Timing Centre (IRNWT)
IRNSS CDMA Ranging Stations (IRCDR)
Laser Ranging Stations
IRNSS Data Communication Network (IRDCN)
The Indian National Centre for Space-based Positioning, Navigation and Timing (NCSPNT) facility located in
Byalalu is responsible for conducting remote operations and data collection with all ground stations.
Currently, 14 IRIMS (Indian Regional Navigational Satellite System Range and Integrity Monitoring Stations)
are operational and are actively contributing to the operations of the IRNSS (Indian Regional Navigation
Satellite System). The four IRCDR (Indian Regional CDMA Ranging) stations regularly perform Code Division
Multiple Access (CDMA) ranging for the IRNSS satellites. The IRDCN (Indian Regional Data Communication
Network) has established both terrestrial and VSAT links between the ground stations. Furthermore, seven
7.2m Fixed Cassegrain Antennas (FCA) and two 11m Fixed Mobile Antennas (FMA) of IRSCF (Indian Regional
Satellite Control Facility) are currently in operation to support both the Launch and Early Orbit Phase
(LEOP) and the on-orbit phases of the IRNSS satellites.
USER SEGMENT:
The User segment mainly consists of:
A single-frequency IRNSS receiver can receive an SPS/RS (Standard Positioning Service/Radio Station) signal
at either the L5 frequency or the S-band frequency.
A sophisticated dual-frequency IRNSS receiver designed to receive both SPS (Standard Positioning Service)
and RS (Restricted Service) signals in the L5 and S-band frequencies, enabling high-precision positioning
and navigation capabilities.