The Indian Regional Navigation Satellite System (IRNSS), which is operationally called NavIC, has been recognized as a component of the World-Wide Radio Navigation System (WWRNS) by the International Maritime Organisation (IMO). IRNSS NavIC is a satellite constellation based navigation service deployed by the Indian Space Research Organization (ISRO) which covers up to 1500 km around the country. NavIC is the Indian regional equivalent of the US Global Positioning System or the GPS.
“IRNSS meets the operational requirements to assist in the navigation of ships in ocean waters within the area covered by 55°E longitude, 50°N latitude, 110°E longitude and 5°S latitude,” notes the IMO Maritime Safety Committee, at its 102nd session (4 to 11 November 2020). The approval was based on the recommendation and assessment made by the Sub-Committee on Navigation, Communications and Search and Rescue (NCSR), at its seventh session (15 to 24 January 2020) after a proposal by India.
However, IMO noted some drawback and correction to the use of the NavIC system which is also common to most Global Navigation Satellite Systems (GNSS). During the port navigation and automatic docking, the accuracy requirement ranges from 10 m to 0.1 m. As per IMO, in the port area, as a stand-alone system, IRNSS will not meet the accuracy requirements. However, the differential correction techniques like DIRNSS (Differential IRNSS) will enhance the accuracy and help meet the accuracy requirements in port areas.
Another drawback is that IRNSS does not provide instantaneous integrity warning of system malfunction. It means that the information accuracy can be lost due to measurement errors or due to the failure of one or more satellites. The IRNSS enables users to determine their position based on the measured pseudo ranges to at least four satellites. IRNSS positioning accuracy is limited by measurement errors. The Ground Control Segment can detect the failure and can send messages to the user but there is a delay between the real failure and the warning which can be of many hours. As per IMO the receiver autonomous integrity monitoring (RAIM), which is developed to assess the integrity of the global positioning system (GPS) signals in a GPS receiver system, can provide this facility.
IRNSS NavIC broadcasts signals at L5 and S-Band. IRNSS composes of a constellation of satellites and a supporting ground segment. Three of the satellites (IRNSS-1C, IRNSS-1F and IRNSS-1G) in the constellation, are placed in a geostationary orbit (GEO) and the remaining five (IRNSS-1A, IRNSS-1B, IRNSS-1D, IRNSS-1E and IRNSS-1I) are located in the geosynchronous orbit (IGSO). One satellite IRNSS-1H failed during the launch. Five more satellites are planned to be launched to the IGSO in the future including IRNSS-1J, IRNSS-1K, IRNSS-1L, IRNSS-1M and IRNSS-1N. In January 2020, ISRO had provided consultation to Qualcomm for integrating NavIC capability in their Snapdragon mobile chipset platforms.
