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The Indian Regional Navigation Satellite System (IRNSS), with an operational name of NavIC (acronym for 'Navigation with Indian Constellation; also, 'sailor' or 'navigator' in Indian languages), is an autonomous regional
satellite navigation A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location ( longitude, latitude, and altitude/ elevation) to hig ...
system that provides accurate real-time positioning and timing services. It covers
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...
and a region extending around it, with plans for further extension. An extended service area lies between the primary service area and a rectangle area enclosed by the
30th parallel south The 30th parallel south is a circle of latitude that is 30 degrees south of the Earth's equator. It stands one-third of the way between the equator and the South Pole and crosses Africa, the Indian Ocean, Australia, the Pacific Ocean, South Am ...
to the
50th parallel north The 50th parallel north is a circle of latitude that is 50 degrees north of the Earth's equatorial plane. It crosses Europe, Asia, the Pacific Ocean, North America, and the Atlantic Ocean. At this latitude the sun is visible for 16 hours, 22 ...
and the 30th meridian east to the 130th meridian east, beyond borders. The system currently consists of a constellation of eight satellites, with two additional satellites on ground as stand-by. The constellation is in orbit as of 2018. NavIC will provide two levels of service, the "standard positioning service", which will be open for civilian use, and a "restricted service" (an encrypted one) for authorised users (including the military). NavIC-based trackers are compulsory on commercial vehicles in India and some consumer
mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whi ...
s with support for it have been available since the first half of 2020. There are plans to expand the NavIC system by increasing its constellation size from 7 to 11.


Background

The system was developed partly because access to foreign government-controlled
global navigation satellite system A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location (longitude, latitude, and altitude/elevation) to high pr ...
s is not guaranteed in hostile situations, as happened to the Indian military in 1999 when the United States denied an Indian request for
Global Positioning System The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite ...
(GPS) data for the Kargil region, which would have provided vital information. The Indian government approved the project in May 2006. As per National Defense Authorization Act 2020,
United States Secretary of Defense The United States secretary of defense (SecDef) is the head of the United States Department of Defense, the executive department of the U.S. Armed Forces, and is a high ranking member of the federal cabinet. DoDD 5100.1: Enclosure 2: a The se ...
in consultation with
Director of National Intelligence The director of national intelligence (DNI) is a senior, cabinet-level United States government official, required by the Intelligence Reform and Terrorism Prevention Act of 2004 to serve as executive head of the United States Intelligence Co ...
will designate NavIC,
Galileo Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He was ...
and QZSS as allied navigational satellite system.


Development

As part of the project, the
Indian Space Research Organisation The Indian Space Research Organisation (ISRO; ) is the national space agency of India, headquartered in Bengaluru. It operates under the Department of Space (DOS) which is directly overseen by the Prime Minister of India, while the Chairman o ...
(ISRO) opened a new satellite navigation centre within the campus of ISRO Deep Space Network (DSN) at Byalalu, in
Karnataka Karnataka (; ISO 15919, ISO: , , also known as Karunāḍu) is a States and union territories of India, state in the southwestern region of India. It was Unification of Karnataka, formed on 1 November 1956, with the passage of the States Reor ...
on 28 May 2013. A network of 21 ranging stations located across the country will provide data for the orbital determination of the satellites and monitoring of the navigation signal. A goal of complete Indian control has been stated, with the space segment,
ground segment A ground segment consists of all the ground-based elements of a space system used by operators and support personnel, as opposed to the space segment and user segment. The ground segment enables management of a spacecraft, and distribution of pay ...
and user receivers all being built in India. Its location in low
latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north ...
s facilitates coverage with low-
inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Ea ...
satellites. Three satellites will be in
geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitu ...
over the
Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by ...
. Missile targeting could be an important military application for the constellation. The total cost of the project was expected to be , with the cost of the ground segment being , each satellite costing and the PSLV-XL version rocket costing around . The planned seven rockets would have involved an outlay of around . The necessity for two replacement satellites, and PSLV-XL launches, has altered the original budget, with the Comptroller and Auditor General of India reporting costs (as of March 2017) of . The NavIC Signal in Space ICD was released for evaluation in September 2014. From 1 April 2019, use of AIS 140 compliant NavIC-based vehicle tracking systems were made compulsory for all commercial vehicles in India. In 2020,
Qualcomm Qualcomm () is an American multinational corporation headquartered in San Diego, California, and incorporated in Delaware. It creates semiconductors, software, and services related to wireless technology. It owns patents critical to the 5G, ...
launched four Snapdragon 4G chipsets and one 5G chipset with support for NavIC. NavIC is planned to be available for civilian use in mobile devices, after Qualcomm and ISRO signed an agreement. To increase compatibility with existing hardware, ISRO will add L1 band support. For strategic application, Long Code support is also coming.


Time-frame

In April 2010, it was reported that India plans to start launching satellites by the end of 2011, at a rate of one satellite every six months. This would have made NavIC functional by 2015. But the program was delayed, and India also launched 3 new satellites to supplement this. Seven satellites with the prefix "IRNSS-1" will constitute the space segment of the IRNSS.
IRNSS-1A IRNSS-1A is the first navigational satellite in the Indian Regional Navigation Satellite System (IRNSS) series of satellites been placed in geosynchronous orbit. Satellite The satellite has been developed at a cost of , and was launched on 1 J ...
, the first of the seven satellites, was launched on 1 July 2013. IRNSS-1B was launched on 4 April 2014 on-board PSLV-C24 rocket. The satellite has been placed in
geosynchronous orbit A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbita ...
. IRNSS-1C was launched on 16 October 2014,
IRNSS-1D IRNSS-1D is a satellite in the Indian Regional Navigational Satellite System (IRNSS) constellation. The satellite is the fourth of seven in the constellation, launched after IRNSS-1A, IRNSS-1B and IRNSS-1C. The satellite is the only satellite ...
on 28 March 2015, IRNSS-1E on 20 January 2016, IRNSS-1F on 10 March 2016 and
IRNSS-1G IRNSS-1G was the seventh and final of the Indian Regional Navigation Satellite System (IRNSS) series of satellites after IRNSS-1A, IRNSS-1B, IRNSS-1C, IRNSS-1D, IRNSS-1E and IRNSS-1F. This system of satellites will provide navigational services ...
was launched on 28 April 2016. The eighth satellite,
IRNSS-1H IRNSS-1H was the eighth in the Indian Regional Navigational Satellite System (IRNSS) series of satellites, after IRNSS-1A, IRNSS-1B, IRNSS-1C, IRNSS-1D, IRNSS-1E, IRNSS-1F and IRNSS-1G. It was lost in the launch failure of PSLV-C39 on August 31, ...
, which was meant to replace IRNSS-1A, failed to deploy on 31 August 2017 as the heat shields failed to separate from the 4th stage of the rocket. IRNSS-1I was launched on 12 April 2018 to replace it.


System description

The IRNSS system comprises a space segment and a support
ground segment A ground segment consists of all the ground-based elements of a space system used by operators and support personnel, as opposed to the space segment and user segment. The ground segment enables management of a spacecraft, and distribution of pay ...
.


Space segment

The constellation consists of 8 satellites. Three of the eight satellites are located in
geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitu ...
(GEO) at
longitude Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek let ...
s 32.5° E, 83° E, and 131.5° E, approximately above Earth's surface. The remaining five satellites are in inclined
geosynchronous orbit A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbita ...
(GSO). Two of them cross the
equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can also ...
at 55° E and two at 111.75° E.


Ground segment

The ground segment is responsible for the maintenance and operation of the IRNSS constellation. The ground segment comprises: * 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 IRSCF is operational at Master Control Facility (MCF), Hassan and Bhopal. The MCF uplinks navigation data and is used for tracking, telemetry and command functions. Seven FCA and two FMA of IRSCF are currently operational for
LEOP In spacecraft operations, Launch and Early Operations (LEOP) is one of the most critical phases of a mission. Spacecraft operations engineers take control of the satellite after it separates from the launch vehicle. LEOP generally concludes once the ...
and on-orbit phases of IRNSS satellites. The INC established at Byalalu performs remote operations and data collection with all the ground stations. The ISRO Navigation Centers (INC) are operational at Byalalu, Bengaluru and Lucknow. INC1 (Byalalu) and INC2 (Lucknow) together provide seamless operations with redundancy. 16 IRIMS are currently operational and are supporting IRNSS operations few more are planned in Brunei, Indonesia, Australia, Russia, France and Japan.
CDMA Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communicatio ...
ranging is being carried out by the four IRCDR stations on regular basis for all the IRNSS satellites. The IRNWT has been established and is providing IRNSS system time with an accuracy of (2 sigma) with respect to UTC. Laser ranging is being carried out with the support of ILRS stations around the world. Navigation software is operational at INC since 1 Aug 2013. All the navigation parameters, such as satellite
ephemeris In astronomy and celestial navigation, an ephemeris (pl. ephemerides; ) is a book with tables that gives the trajectory of naturally occurring astronomical objects as well as artificial satellites in the sky, i.e., the position (and possibly ...
, clock corrections, integrity parameters, and secondary parameters, such as iono-delay corrections, time offsets with respect to UTC and other GNSSes,
almanac An almanac (also spelled ''almanack'' and ''almanach'') is an annual publication listing a set of current information about one or multiple subjects. It includes information like weather forecasts, farmers' planting dates, tide tables, and othe ...
, text message, and earth orientation parameters, are generated and uploaded to the spacecraft automatically. The IRDCN has established terrestrial and
VSAT A very-small-aperture terminal (VSAT) is a two-way satellite ground station with a dish antenna that is smaller than 3.8 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Bit rates, in most cases, range from 4 kbit/s up to 1 ...
links between the ground stations. As of March 2021, ISRO and
JAXA The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into o ...
are performing calibration and validation experiments for NavIC ground reference station in Japan. ISRO is also under discussion with CNES for a NavIC ground reference station in France. ISRO is planning a NavIC ground station at Cocos (Keeling) Islands and is in talks with the
Australian Space Agency The Australian Space Agency is an agency under the Australian Government responsible for the development of Australia's commercial space industry, coordinating domestic activities, identifying opportunities and facilitating international spac ...
.


Signal

NavIC signals will consist of a Standard Positioning Service and a Precision Service. Both will be carried on L5 (1176.45 MHz) and S band (2492.028 MHz). The SPS signal will be modulated by a 1 MHz BPSK signal. The Precision Service will use BOC(5,2). The navigation signals themselves would be transmitted in the
S-band The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave radio band, band of the electromagnetic spectrum covering frequency, frequencies from 2 to 4 gigahertz (GHz). Thus it c ...
frequency (2–4 GHz) and broadcast through a phased array antenna to maintain required coverage and signal strength. The satellites would weigh approximately and their solar panels generate 1,400 W. A messaging interface is embedded in the NavIC system. This feature allows the command center to send warnings to a specific geographic area. For example, fishermen using the system can be warned about a cyclone.


Accuracy

The Standard Positioning Service system is intended to provide an absolute position accuracy of about 5 to 10 metres throughout the Indian landmass and an accuracy of about in the Indian Ocean as well as a region extending approximately around India. GPS, for comparison, has a position accuracy of 5 m under ideal conditions. However, unlike GPS, which is dependent only on L-band, NavIC has dual frequencies (S and L bands). When a low-frequency signal travels through atmosphere, its velocity changes due to atmospheric disturbances. The US banks on an atmospheric model to assess frequency error, and it has to update this model from time to time to assess the exact error. In India's case, 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 and is more accurate than GPS.


List of satellites

The constellation consists of 7 active satellites. Three of the seven satellites in constellation are located in
geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitu ...
(GEO) and four are in inclined
geosynchronous orbit A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbita ...
(IGSO). All satellites launched or proposed for the system are as follows:


IRNSS series satellites


NVS series satellite


Clock failure

In 2017, it was announced that all three SpectraTime supplied
rubidium Rubidium is the chemical element with the symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. Rubidium is the first alkali metal in the group to have a density higher ...
atomic clock An atomic clock is a clock that measures time by monitoring the resonant frequency of atoms. It is based on atoms having different energy levels. Electron states in an atom are associated with different energy levels, and in transitions betwe ...
s on board
IRNSS-1A IRNSS-1A is the first navigational satellite in the Indian Regional Navigation Satellite System (IRNSS) series of satellites been placed in geosynchronous orbit. Satellite The satellite has been developed at a cost of , and was launched on 1 J ...
had failed, mirroring similar failures in the European Union's Galileo constellation. The first failure occurred in July 2016, followed soon after by the two other clocks on IRNSS-1A. This rendered the satellite non-functional and required replacement. ISRO reported it had replaced the atomic clocks in the two standby satellites, IRNSS-1H and IRNSS-1I in June 2017. The subsequent launch of IRNSS-1H, as a replacement for IRNSS-1A, was unsuccessful when PSLV-C39 mission failed on 31 August 2017. The second standby satellite, IRNSS-1I, was successfully placed into orbit on 12 April 2018. In July 2017, it was reported that two more clocks in the navigational system had also started showing signs of abnormality, thereby taking the total number of failed clocks to five, in May 2018 a failure of a further 4 clocks was reported, taking the count to 9 of the 24 in orbit. As a precaution to extend the operational life of navigation satellite, ISRO is running only one rubidium atomic clock instead of two in the remaining satellites.


Future developments

India's
Department of Space The Department of Space is an Indian government department responsible for administration of the Indian space program. It manages several agencies and institutes related to space exploration and space technologies. The Indian space program un ...
in their 12th Five Year Plan (FYP) (2012–17) stated increasing the number of satellites in the constellation from 7 to 11 to extend coverage. These additional four satellites will be made during 12th FYP and will be launched in the beginning of 13th FYP in
geosynchronous orbit A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbita ...
of 42° inclination. Also, the development of space-qualified Indian made atomic clocks was initiated, along with a study and development initiative for an all optical atomic clock (ultra stable for IRNSS and deep space communication). ISRO will be launching five next generation satellite featuring new payloads and extended lifespan of 12 years. Five new satellites viz. 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 introduces a new interoperable civil signal in the L1 band in the navigation payload and will use Indian Rubidium Atomic Frequency Standard (iRAFS). This introduction of the new L1 band will help facilitate NavIC proliferation in wearable smart and
IoT The Internet of things (IoT) describes physical objects (or groups of such objects) with sensors, processing ability, software and other technologies that connect and exchange data with other devices and systems over the Internet or other comm ...
devices featuring a low power navigation system. NVS-01 is a replacement for
IRNSS-1G IRNSS-1G was the seventh and final of the Indian Regional Navigation Satellite System (IRNSS) series of satellites after IRNSS-1A, IRNSS-1B, IRNSS-1C, IRNSS-1D, IRNSS-1E and IRNSS-1F. This system of satellites will provide navigational services ...
satellite and will launch on GSLV-Mk2 in 2022.


Global Indian Navigation System

Study and analysis for the Global Indian Navigation System (GINS) was initiated as part of the technology and policy initiatives in the 12th FYP (2012–17). The system is supposed to have a constellation of 24 satellites, positioned above Earth. , the statutory filing for frequency spectrum of GINS satellite orbits in international space, has been completed. As per new 2021 draft policy, ISRO and
Department of Space The Department of Space is an Indian government department responsible for administration of the Indian space program. It manages several agencies and institutes related to space exploration and space technologies. The Indian space program un ...
(DoS) is working on expanding the coverage of NavIC from regional to global that will be independent of other such system currently operational namely GPS,
GLONASS GLONASS (russian: ГЛОНАСС, label=none, ; rus, links=no, Глобальная навигационная спутниковая система, r=Global'naya Navigatsionnaya Sputnikovaya Sistema, t=Global Navigation Satellite System) is ...
,
BeiDou The BeiDou Navigation Satellite System (BDS; ) is a Chinese satellite navigation system. It consists of two separate satellite constellations. The first BeiDou system, officially called the BeiDou Satellite Navigation Experimental System a ...
and
Galileo Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He was ...
while remain interoperable and free for global public use. ISRO has proposed to Government of India to expand the constellation for global coverage by initially placing twelve satellites in
Medium Earth Orbit A medium Earth orbit (MEO) is an Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level.
(MEO).


See also

* GPS Aided GEO Augmented Navigation * Quasi-Zenith Satellite System


References


Footnotes

# SATNAV Industry Meet 2006. ISRO Space India Newsletter. April – September 2006 Issue.


External links


IRNNS programme
{{Portal bar, Spaceflight, Geography, India ISRO programs Navigation satellite constellations 2013 establishments in India