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Indian Regional Navigation Satellite System
Satellite navigation system

The Indian Regional Navigation Satellite System (IRNSS), known as NavIC (Navigation with Indian Constellation), is an autonomous regional satellite navigation system providing accurate real-time positioning and timing over India and surrounding areas up to 1,500 km, with plans to extend coverage to 3,000 km. Its extended service area ranges between the 30th parallel south and 50th parallel north, and between the 30th meridian east and 130th meridian east. Operating since 2018 with eight satellites and backups, NavIC offers a civilian standard positioning service and an encrypted restricted service for authorized users. It is mandatory on commercial vehicles and supported by some mobile phones, with plans to expand the constellation to 11 satellites.

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Background

The system was developed partly because access to foreign government-controlled global navigation satellite systems 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 (GPS) data for the Kargil region, which would have provided vital information.21 The Indian government approved the project in May 2006.2223

Developments

First Generation

As part of the project, the Indian Space Research Organisation (ISRO) opened a new satellite navigation centre within the campus of ISRO Deep Space Network (DSN) at Byalalu, in Karnataka on 28 May 2013.24 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 and user receivers all being built in India. Its location in low latitudes facilitates coverage with low-inclination satellites. Three satellites will be in geostationary orbit over the Indian Ocean. Missile targeting could be an important military application for the constellation.25

The total cost of the project was expected to be ₹14.2 billion (US$168 million), with the cost of the ground segment being ₹3 billion (US$35 million), each satellite costing ₹1.5 billion (US$18 million) and the PSLV-XL version rocket costing around ₹1.3 billion (US$15 million). The planned seven rockets would have involved an outlay of around ₹9.1 billion (US$108 million).262728

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 ₹22.46 billion (US$266 million).29

India's Department of Space 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.30 These additional four satellites will be made during 12th FYP and will be launched in the beginning of 13th FYP (2018–23) in geosynchronous orbit of 42° inclination.3132 Also, the development of space-qualified Indian made atomic clocks was initiated,33 along with a study and development initiative for an all optical atomic clock (ultra stable for IRNSS and deep space communication).3435

The NavIC Signal in Space ICD was released for evaluation in September 2014.36

From 1 April 2019, use of AIS 140 compliant NavIC-based vehicle tracking systems were made compulsory for all commercial vehicles in India.3738

In December 2019, the United States Congress consented to designate NaVIC as one of their allied navigational satellite systems along with Galileo (Europe) and QZSS (Japan). The approval was as a part of National Defense Authorization Act 2020. The proposal was put forward by United States Secretary of Defense in consultation with Director of National Intelligence.3940

Clock failure

In 2017, it was announced that all three SpectraTime supplied rubidium atomic clocks on board IRNSS-1A had failed, mirroring similar failures in the European Union's Galileo constellation.4142 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.43 ISRO reported it had replaced the atomic clocks in the two standby satellites, IRNSS-1H and IRNSS-1I in June 2017.44 The subsequent launch of IRNSS-1H, as a replacement for IRNSS-1A, was unsuccessful when PSLV-C39 mission failed on 31 August 2017.4546 The second standby satellite, IRNSS-1I, was successfully placed into orbit on 12 April 2018.47

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,48 in May 2018 a failure of a further 4 clocks was reported, taking the count to 9 of the 24 in orbit.49

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.50

As of May 2023 only four first generation satellites were capable of providing navigation services51 which is the minimum number required for service to remain operational.52

As of September 2024 only four satellites IRNSS-1B, IRNSS-1F, IRNSS-1I and NVS-01 were capable of providing navigation services.5354

Indian Atomic clock

In order to reduce the dependency on imported frequency standards ISRO's Space Applications Centre (SAC), Ahmedabad had been working on domestically designed and developed Rubidium based atomic clocks.55565758 To overcome the clock failures on first generation navigation satellites and its subsequent impact on NavIC's position, navigation, and timing services, these new clocks would supplement the imported atomic clocks in next generation of navigation satellites.59606162

On 5 July 2017, ISRO and Israel Space Agency (ISA) signed an Memorandum of Understanding to collaborate on space qualifying a Rubidium Standard based on AccuBeat model AR133A and to test it on an ISRO satellite.63

The clocks are utilised by the NVS series of satellites.64 As part of the Times Dissemination Project, which is overseen by the Ministry of Consumer Affairs, Food, and Public Distribution, NavIC will take the position of GPS as the reference time provider at the National Physical Laboratory of India from 2025.65

NavIC chip

In accordance with the range requirements for NavIC for both military and commercial applications, Defence Research and Development Organisation, through the Technology Development Fund scheme, has commissioned Accord Software and Systems, to build a tailored and flexible IRNSS Network Timing system domestically. Using NavIC data, the receiver chip will obtain and distribute Indian time for navigation. India currently depends on the US for this service.66

In 2020, Qualcomm launched four Snapdragon 4G chipsets and one 5G chipset with support for NavIC.6768 NavIC is planned to be available for civilian use in mobile devices, after Qualcomm and ISRO signed an agreement.6970 To increase compatibility with existing hardware, ISRO will add L1 band support. For strategic application, Long Code support is also coming.7172

On December 7, 2023, Qualcomm revealed that select chipset platforms will enable NavIC L1 signals. The Qualcomm location suite, supports up to seven satellite constellations simultaneously and allows for faster Time to First Fix (TTFF) position acquisition for enhanced location-based services. It also makes use of all of NavIC's L1 and L5 signals for precise positioning. In the second half of 2024, Qualcomm chipset platforms will add further support for the NavIC L1 signals, and in the first half of 2025, commercial products that support the NavIC L1 signals should be available for sale.7374

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,75 and India also launched 3 new satellites to supplement this.76

Seven satellites with the prefix "IRNSS-1" will constitute the space segment of the IRNSS. IRNSS-1A, the first of the seven satellites, was launched on 1 July 2013.7778 IRNSS-1B was launched on 4 April 2014 on-board PSLV-C24 rocket. The satellite has been placed in geosynchronous orbit.79 IRNSS-1C was launched on 16 October 2014,80 IRNSS-1D on 28 March 2015,81 IRNSS-1E on 20 January 2016,82 IRNSS-1F on 10 March 2016 and IRNSS-1G was launched on 28 April 2016.83

The eighth satellite, IRNSS-1H, 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.84 IRNSS-1I was launched on 12 April 2018 to replace it.8586

System description

The IRNSS system comprises a space segment and a support ground segment.

Space segment

The constellation consists of 7 satellites. Three of the seven satellites are located in geostationary orbit (GEO) at longitudes 32.5° E, 83° E, and 131.5° E, approximately 36,000 km (22,000 mi) above Earth's surface. The remaining four satellites are in inclined geosynchronous orbit (GSO). Two of them cross the equator at 55° E and two at 111.75° E.878889

Ground segment

The ground segment is responsible for the maintenance and operation of the IRNSS constellation. The ground segment comprises:90

  • 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.91 Seven 7.2-metre (24 ft) FCA and two 11-metre (36 ft) FMA of IRSCF are currently operational for LEOP and on-orbit phases of IRNSS satellites.9293

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.94

16 IRIMS are currently operational and are supporting IRNSS operations.95 A few more are planned in Brunei, Indonesia, Australia, Russia, France and Japan.96 CDMA ranging is being carried out by the four IRCDR stations on a regular basis for all the IRNSS satellites. The IRNWT has been established and is providing IRNSS system time with an accuracy of 2 ns (2.0×10−9 s) (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, clock corrections, integrity parameters, and secondary parameters, such as iono-delay corrections, time offsets with respect to UTC and other GNSSes, almanac, text message, and earth orientation parameters, are generated and uploaded to the spacecraft automatically. The IRDCN has established terrestrial and VSAT links between the ground stations. As of March 2021, ISRO and JAXA are performing calibration and validation experiments for NavIC ground reference station in Japan.97 ISRO is also under discussion with CNES for a NavIC ground reference station in France.98 ISRO is planning a NavIC ground station at Cocos (Keeling) Islands and is in talks with the Australian Space Agency.99

Signal

NavIC signals will consist of a Standard Positioning Service and a Restricted Service. Both will be carried on L5 (1176.45 MHz) and S band (2492.028 MHz).100 The SPS signal will be modulated by a 1 MHz BPSK signal. The Restricted Service will use BOC(5,2). The navigation signals themselves would be transmitted in the L5 (1176.45 MHz) & S band (2492.028 MHz) frequencies and broadcast through a phased array antenna to maintain required coverage and signal strength. The satellites would weigh approximately 1,330 kg (2,930 lb) 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.101

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 20 metres (66 ft) in the Indian Ocean as well as a region extending approximately 1,500 km (930 mi) around India.102103 GPS, for comparison, has a position accuracy of 5 m under ideal conditions.104 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. GPS depends 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 NavIC, 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 can be more accurate than GPS.105

Future developments

NVS series

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.)106107108109 This introduction of the new L1 band will help facilitate NavIC proliferation in wearable smart and IoT devices featuring a low power navigation system. NVS-01 is a replacement for IRNSS-1G satellite and was launched on GSLV in 2023.110111112

ISRO has plans for a total of 7 NVS series satellites (including already launched NVS-1) for civilian navigation requirements. The IRNSS network is, as of November 2024, confined to strategic use by the Indian Armed Forces. They will be equipped with L1 band along with the L5 and S band. The system will provide an accuracy of 10 m (33 ft) within India, 20 m (66 ft) for the area surrounding India by 1,500 km (930 mi).113114

Approved project cost of first five NVS satellites (NVS-01 to NVS-05) is ₹964.68 crore (equivalent to ₹10 billion or US$120 million in 2023) excluding the launch costs.115

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).116 The system is supposed to have a constellation of 24 satellites, positioned 24,000 km (14,913 mi) above Earth. As of 2013, the statutory filing for frequency spectrum of GINS satellite orbits in international space, has been completed.117 As per new 2021 draft policy,118 ISRO and Department of Space (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, BeiDou and Galileo while remaining interoperable and free for global public use.119 ISRO has proposed to Government of India to expand the constellation for global coverage by initially placing twelve satellites in Medium Earth Orbit (MEO).120

List of satellites

The constellation consists of 7 active satellites. Three of the seven satellites in constellation are located in geostationary orbit (GEO) and four are in inclined geosynchronous orbit (IGSO). All satellites launched or proposed for the system are as follows:

IRNSS series satellites

IRNSS-1 series satellites121122
SatelliteSVNPRNInt. Sat. IDNORAD IDLaunch DateLaunch VehicleOrbitStatusRemarks
IRNSS-1AI001I012013-034A391991 July 2013PSLV-XL-C22Geosynchronous (IGSO) / 55°E, 29° inclined orbitPartial FailureAtomic clocks failed. The satellite is being used for NavIC's short message broadcast service.123124125
IRNSS-1BI002I022014-017A396354 April 2014PSLV-XL-C24Geosynchronous (IGSO) / 55°E, 29° inclined orbitOperational126
IRNSS-1CI003I032014-061A4026916 October 2014PSLV-XL-C26Geostationary (GEO) / 83°E, 5° inclined orbitPartial Failure127
IRNSS-1DI004I042015-018A4054728 March 2015PSLV-XL-C27Geosynchronous (IGSO) / 111.75°E, 31° inclined orbitPartial Failure128129130
IRNSS-1EI005I052016-003A4124120 January 2016PSLV-XL-C31Geosynchronous (IGSO) / 111.75°E, 29° inclined orbitPartial FailureThe satellite is being used for NavIC's short message broadcast service.131132133
IRNSS-1FI006I062016-015A4138410 March 2016PSLV-XL-C32Geostationary (GEO) / 32.5°E, 5° inclined orbitOperational134
IRNSS-1GI007I072016-027A4146928 April 2016PSLV-XL-C33Geostationary (GEO) / 129.5°E, 5.1° inclined orbitPartial FailureReplaced by NVS-01.Currently being used for NavIC's short message broadcast service.135136137
IRNSS-1HI008I0831 August 2017PSLV-XL-C39Geosynchronous (IGSO) / 55°E, 29° inclined orbitLaunch FailedThe payload fairing failed to separate and satellite could not reach the desired orbit.138139 It was meant to replace defunct IRNSS-1A.140141
IRNSS-1II009I092018-035A4328612 April 2018PSLV-XL-C41Geosynchronous (IGSO) / 55°E, 29° inclined orbitOperational142

NVS series satellite

NVS series satellites143144
SatelliteSVNPRNInt. Sat. IDNORAD IDLaunch DateLaunch VehicleOrbitStatusRemarks
NVS-01 (IRNSS-1J)I010I102023-076A5675929 May 2023145146GSLV Mk II - F12147Geostationary (GEO) / 129.5°E, 5.1° inclined orbitOperationalReplaced IRNSS-1G. Features extended lifespan, indigenous clock and new civilian band L1 for low power devices.148149150
NVS-02 (IRNSS-1K)29 January 2025151GSLV Mk II - F15Partial FailureIntended replacement of malfunctioning IRNSS-1E satellite.152153154 However, NVS-02 suffered from a propulsion system failure and the ISRO is looking for alternative uses for the satellite.155156
NVS-03 (IRNSS-1L)2026GSLV Mk IIGeosynchronous (IGSO), 32.5°E or 129.5°E, 29° inclined orbitPlanned157
NVS-04 (IRNSS-IM)2026GSLV Mk IIGeosynchronous (IGSO), 32.5°E or 129.5°E, 29° inclined orbitPlanned158159160
NVS-05 (IRNSS-1N)2027GSLV Mk IIGeosynchronous (IGSO), 32.5°E or 129.5°E, 29° inclined orbitPlanned161162163
NVS-06 (IRNSS-1O)2028Planned164
NVS-07 (IRNSS-1P)2029Planned165

See also

Footnotes

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

References

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