What is NavIC?

What is NavIC or NAVigation with Indian Constellation? How is it related to IRNSS?

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- everything RF

Jan 9, 2022

NavIC (NAVigation with Indian Constellation) is the operational name of the Indian Regional Navigation Satellite System (IRNSS), which is an independent regional navigation satellite system being developed by India. This is India’s version of GPS. It has been 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.

NavIC provides two types of services:

  • Standard Positioning Service (SPS): This service is for civilian use and can be used by all users.
  • Restricted Service (RS): This services is encrypted and can only by used by authorized users (military purposes).

The constellation currently consists of 8 satellites that have been in orbit since 2018 with an additional satellite on the ground as stand-by. NavIC operates in the L-band frequency of 1176.45 MHz & S-band frequency of 2492.028 MHz and provides a position accuracy of better than 20 m in the primary service area.

Unlike GPS, which is solely dependent on L-band, NavIC’s utilization of dual frequencies make it more accurate for positioning. When a low-frequency signal travels through the atmosphere, its velocity changes due to atmospheric disturbances. GPS uses an atmospheric model to assess frequency error and it has to update this model from time to time to assess and the exact error. In the NavIC system, the actual delay is assessed by measuring the difference in delay of the two frequencies (S and L bands). Therefore, NavIC is not dependent on any model to find the frequency error making the error finding process more efficient than in GPS.

As part of the project, the Indian Space Research Organisation (ISRO) will set up a network of 21 ranging stations located across the country to provide data for the orbital determination of the satellites and monitoring of the navigation signal. NavIC comprises a space segment and a support ground segment.

Space segment: Out of the 8 satellites of NavIC, three of the eight satellites are located in geostationary orbit (GEO) and the remaining five satellites are in inclined geosynchronous orbit (GSO). The 8 satellites (+1 on stand-by) of NavIC are namely:

  • IRNSS-1A
  • IRNSS-1B
  • IRNSS-1C
  • IRNSS-1D
  • IRNSS-1E
  • IRNSS-1F
  • IRNSS-1G
  • IRNSS-1H (On stand-by)
  • IRNSS-1I

Ground Segment: The Ground Segment is responsible for the maintenance and operation of the IRNSS constellation. It comprises 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)

Some applications of IRNSS are:

  • Terrestrial, Aerial and Marine Navigation
  • Disaster Management
  • Vehicle tracking and fleet management
  • Integration with mobile phones
  • Precise Timing
  • Mapping and Geodetic data capture
  • Terrestrial navigation aid for hikers and travelers
  • Visual and voice navigation for drivers

NavIC’s IRNSS-1A satellite provides messaging services to users in the Indian region. The “Signal-in-Space Interface Control Document (ICD Ver. 1.0) for Messaging services (IRNSS 1A)” is released to the public to provide the essential information to facilitate the use of IRNSS-1A Signal-in-space for the development of receivers and associated applications. This messaging interface is embedded in the NavIC system. It allows the command center to send warnings to a specific geographic area. For instance, fishermen using the system can be warned about a cyclone. NavIC based trackers are compulsory on commercial vehicles in India and some consumer mobile phones with support for it have been available since the first half of 2020.

India’s Department of Space has announced 4 more satellites which will take the total satellite count to 12. ISRO will also be launching five next generation satellites featuring new payloads with an extended lifespan of 12 years. These five new satellites - NVS-01, NVS-02, NVS-03, NVS-04 and NVS-05 - will supplement and augment the current constellation of satellites. The new satellites will feature the L5 and S-band and introduce a new interoperable civil signal in the L1 band in the navigation payload and will use the Indian Rubidium Atomic Frequency Standard (iRAFS). This introduction of the new L1 band will help cater to NavIC proliferation in wearable smart and IoT devices featuring low power navigation systems. NVS-01 is a replacement for the IRNSS-1G satellite and will launch in 2022.

Click here to learn about IRNSS.

Click here to learn about IRNSS frequency bands.