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India’s Strategic Guardian of the Sky: IRNSS; By Vithiyapathy Purushothaman

 Occasional Paper – 001/2015 

Courtesy: KW Publishers


Dedicated to Missile Man Dr. A. P. J. Abdul Kalam Sir, who sowed the seeds of dreams in youngsters’ minds.    


It has been a long, arduous and yet productive journey for the space scientists in India. From a small sounding rocket sent from Thumba, India today has become a favourite destination for launching western satellites and even NASA would launch its pay loads from the PSLV in 2015-2016.  The entire space programme has been assiduously built on the capability of both the pay load and the launch platforms. The sustained efforts and vision of ISRO and DRDO has ensured that the nation is on the path to enabling the nation to build its own systems and solutions for meeting the needs of a growing India.

The challenges are many and accurate navigation is one of the most important dimensions of space based systems. It is here that the IRNSS has many opportunities both at the tactical, strategic and international level. The successful completion of the GAGAN has ensured that the dependency on American/European satellite systems is overcome. Any home grown solution would in the long run ensure that there are no surprises in terms of turning off  a system by the owner or selectively degrading the capability of the system to ensure that the desired outcome in a battle is not achieved. The steady progress in the space segment and the commissioning of the IRNSS will ensure that India has the potential to keep an eye in the areas of interest and also provide its own navigational solutions for navigation, weapon delivery and many other peace time applications. The declaration of the Prime Minister that such capability should be shared with the neighbours in SAARC augurs well in terms of India’s long term strategy to assist the neighbouring nations in their own thrust for moving forward in this challenging century.

Vithiyapathy’s occasional paper in all sense provides the required inputs and analysis of a new found capability of India which has achieved the distinction of being amongst the best when it comes to space exploration and putting the space to better use for the common good of the mankind.  The researcher needs to be complemented for tackling a difficult technically challenging topic and bringing it within the reach of the curious reader who would like to be informed of the potential of the IRNSS/GAGAN and other related systems and sub systems. It is hoped that this occasional paper will generate enough interest among the readers to bring about greater awareness on Indian initiatives in the final frontier of space which is being harnessed for reaping enormous benefits across the board

– Commodore.  R. S. Vasan (IN Retd.),  Director, C3S.


India is the sixth country in this world to establish its own SBAS (Satellite Based Augmentation System) called GAGAN (GPS-aided Geo-augmented Navigation) and IRNSS (Indian Regional Navigation Satellite system) an indigenous regional satellite navigation system. GAGAN provides real-time position, navigation, and timing (PNT) services. It is to be noted that GAGAN means ‘Sky’ in Sanskrit.

There are three ‘Global Navigation Satellite Systems (GNSS)’ such as GPS (Global Positioning System) of United States, GLONASS (Global Satellite Navigation System) of Russia, Galileo (under development) of European Union and Compass/BeiDou-2 (under development) of China. There are two ‘Regional Satellite Navigation Systems’ are QZSS (Quasi-Zenith Satellite System) of Japan and Compass of China.[1]

Map 1: Six Global Navigation satellite system’s of the world [2]


The above mentioned GNSS provide various services. GPS provides WAAS (Wide Area Augmentation System), EGNOS (European Geostationary Navigation Overlay Service) provides Galileo, System of Differential Correction and Monitoring (SDCM) provides GLONASS, Beidou provides Compass, QZSS provides MTSAT Satellite Augmentation System (MSAS) and IRNSS provides GPS-aided Geo-augmented Navigation (GAGAN).[3]

What are the available Global Satellite Navigation Systems? What are the events that led India to obtain its own satellite system?  How does IRNSS work?  How do they differ from other SBAS? How can its interoperability be used to connect with other satellite navigation systems?    How can cooperation between Compass  and IRNSS give the region an advantage in navigation?

Historical Analysis

It is believed that the word ‘navigation’ is derived from Sanskrit word ‘navv’ means ‘ship’ and ‘gathi’ means ‘speed’.[4] The great Sanskrit scholar  Kalidas who lived in 5th  century A.D during the Gupta Empire[5] was the first to imagine about land navigation in his famous Sanskrit Kavya “Meghadūtat” [6] in which Yaksha instructs ‘Megha’ (clouds) to navigate from Ramagiri to Alkapuram[7]. These historical scripts make one clearly understand how Indians in the golden ancient age had navigated around the world.

On 11 May 1998, India surprised the world with its Operation Shakti (Pokhran-II) nuclear test, which was completely hidden from US spy satellites. This was a feat as the US spy satellites are capable of taking even a snap of wristwatch of the Indian soldiers.  When India felt the importance of secrecy and to avoid being detected by other countries, it integrated the 58th Engineer Regiment with DRDO (Defence Research and Development Organisation) the latter being lead by chief scientists Dr. A.P.J Abdul Kalam and Dr. R. Chidambaram.  The objective was to camouflage the nuclear test site.

The extensive and intelligent work of a very small group of Indian scientists helped to prevent the detection of test sites from orbiting satellites of several countries. This was done by calculating their movement, visibility and organising the movements of materials accordingly.  Notably, they remained undetected even in the desert regions of Rajasthan. From the analysis of information about the orbiting satellite movement provided by scientists, the Indian Army moved the objects and prepared the test sites and also made sure that the satellite images do not have any trace of these movements. India successfully conducted the test without being detected in any satellite images and world was aware about the test only when former Prime Minister Atal Bihari Vajpayee unveiled to press about India’s capacity to become a full-fledged nuclear weapon state[8]. We can understand India’s capability in analysing the moving satellites and the science of intelligence behind being camouflaged. Thus the orbiting satellites of all the nations are been evaded with the dexterity of the Indian scientists.

Picture 1: Scientists in military outfit present at Pokhran –II nuclear test site [9]


Dr. A. P. J. Abdul Kalam, standing second from left in military suit.

In May – July 1999 India had realized the inevitable requirement of GNSS during Kargil War[10]. If United States had provided its GNSS information, Indian Military forces would have access to conventional compasses in order to find the forces’ location, deployment and enhancement of ground awareness towards obtaining the accurate position of their own units. Further it would have detected the Pakistani troops and its movements in the region.[11] The Indian Government requested United States to provide GPS data for these purposes during Kargil War but it was denied.

Map 2: Kargil location [12]


“Geopolitical needs teach you that some countries can deny you the service in times of conflict. It’s also a way of arm twisting and a country should protect itself against that…”

– S.Ramakrishnan, Director of Vikram Sarabhai Space Centre, Thiruvananthapuram. [13]

India understood the inevitable need of navigation systems as realised from its Kargil experience.  Later in May 2006, the IRNSS’s R&D programme was approved.[14] IRNSS can provide an absolute position with high accuracy real time position, velocity and time (PVT) for authorised users on different platforms on a 24 – hour basis during all weather operations. Hence, IRNSS will provide the positioning service to civilians and the military[15]. This makes India to be self reliant on its technology that provides 24 – hour service in all weather operation, with high accuracy.

IRNSS Constellation

IRNSS (Indian Regional Navigational Satellite System) is an independent regional satellite navigation system being indigenously developed by ISRO. From the past experience of Operation Shakti (Pokhran-II) nuclear test, of May 1999, India understood the drawback of orbiting satellites. It planned for a constellation of seven satellites where three satellites in Geostationary Earth Orbit (GEO) will appear fixed in the sky located at 34° E, 83° E and 131.5° E[16].  Four satellites will appear in Geosynchronous Orbit (GSO) revolving in independent 29° inclination and two each with the equator crossing at 55° E and 111° E. By successfully controlling all the seven satellites IRNSS will provide two services such as SPS (Standard Positioning Service) and RS (Restricted Service) signals.[17] Since, the system is designed and developed by ISRO it shall be independently controlled by Indian Government.[18]

Map 3: IRNSS Constellation [19]


The IRNSS satellites’ payload has a mass of 1,330 kg and two solar panels capable of generating 1,600 Watt[20] . It also consists of two solid state power amplifiers of 40 Watt along with four units that help in generating navigation signals such as clock management and control unit, redundant on-board atomic unit, frequency generation and modulation unit in addition with navigation processor and signal generation unit.  To meet the needs of high performance, a phased array antenna Code Division Multiple Access (CDMA) signal structure is used with S-band navigation signals.[21] There is also a data structure of 50 bits per second along with the super frame of 1500 bits that includes clock correction for improved accuracy and integrity. [22]

Operations of IRNSS

IRNSS functions can be classified into three segments which include ground, space and user segments. The ground segment involves controlling the satellite network from the navigation control centre which tracks the satellite orbit and ensures the satellite’s health; space segment is a consortium of 7 satellites with downlink signals; and user segment serves for single frequency user and dual frequency user.

Fig 1: Earth Orbit and the satellite systems [23]


A cluster of seven satellites forms the space segment with downlink signals where the ground segment is involved in controlling the satellite network from the navigation control and support facilities. It provides users with L5-band (1164.45MHz-1188.45MHz) and S-band frequencies (2483.778MHz-2800.278MHz) and provides services such as SPS (Standard Positioning Service), RS (Restricted /Authorized Service) data and RS pilot[24]. Thus the satellite is positioned in such a way that it could give a clear view of the observation zone and provide uninterrupted data at any time.  In the above picture we can see that the IRNSS satellites are placed in High Earth Orbit (HEO) at 35,786 kilometres (22,236 miles) and these three Geostationary as well as four geosynchronous satellites provide an eye from the sky.

Fig 2: IRNSS Operation Model [25]


The ground segment controls the satellite constellation and consists of the INC, IRTTC, IRSCF, IRDCN, IRIMS, ILRS, IRNWT, IRSCC, and IRCDR stations.[26]  There are 17 IRIMS sites for determining the orbit and 4 IRCDR stations which provides two-way CDMA (Code Division Multiple Access).

INC (ISRO Navigation Centre) at Byalalu which serves as a nerve center for the ground segment and generates primary navigation parameters. Further it estimates and predicts ephemeris, maintain IRNSS time, determines ionospheric correction and integrity. At the end it transmits the clock and its correction to IRTTC (IRNSS TTC and Land Uplink Stations) for uplinking it to IRNSS.

IRSCF (IRNSS Spacecraft Control Facility) maintains the satellite constellation.

IRDCN (IRNSS Data Communication Network) serves as a backbone of digital communication of IRNSS.

IRIMS (IRNSS Range and Integrity Monitoring Stations) receives the data from GEO and GSO, transmits the data to IRNCC (IRNSS Navigation Control Center), thus this station is used for uninterrupted one way ranging which helps in determining the integration of the IRNSS constellation.

ILRS (Laser Ranging Station), IRNWT (Timing Centre),  IRSCC (IRNSS Satellite Control Center)  and thereby IRCDR (CDMA Ranging Stations) carry out more precise two way ranging[27] These ground stations help in operation, monitoring and time determination to control the space segment by tracking, up-linking the navigation parameters and downlinks the data.

The 17 IRIM stations will send the data in two way communication to IRNWT timing center where it links for the correction of errors and will provide a CDMA ranging or Laser Ranging data. Hence the SCF located at Hassan and Bhopal will manipulate the data by receiving it from IRLUS. Thus the satellite navigation and positioning is made available with this information. The backup for each data is stored in INC located at Baylalu.[28]

The SCC and the INC will be the core of the ground segment. They are in charge of estimating and predicting IRNSS satellites position, calculation of integrity, ionospheric and clock corrections and running the navigation software.

The user segment has freedom to choose between L5 and S band depending on their need of the application and is thus different from single frequency user such as basic hand-held receiver or highly sophisticated dual frequency user which requires complete information on PVT. Hence it provides two services SPS and RS using BPSK (1) (bi-phase shift keying), binary offset carrier (BOC (5, 2)) modulation respectively. Consequently to achieve the required signal coverage and strength, the navigational signals are transmitted in S-band frequency ranging from 2-4 GHz which are broadcasted through array antennas.[29]

The satellite contains 3 axis controls for providing a more stable frequency reference. Each IRNSS satellite is equipped with RAFS (Rabidium Atomic frequency standards) with sophisticated payload that generates the navigational downlink signal.  The ground station of IRNSS gives its strength in observation, monitoring, uplink and downlink of data, the stations are highly integrated and while comparing to other GNSS, IRNSS is supreme in its operations in means of the integration and innovation.

Map 3: IRNSS Ground Segment [30]


Therefore, IRNSS is ready to assist India in all aerial, terrestrial and marine navigations with its accuracy of navigation. Its service through RS signal will help Indian armed forces for precision guidance with the notable 20 meters accuracy which is comparably one among the best in the world[31]. Its field of assistance SPS involves capturing geodetic data, analyzing tectonic movements and will provide data which can be utilized in farming, traffic management, and terrestrial navigation in all terrains which helps the users such as commuters, hikers and excursionists.

Strategic Importance of IRNSS

India learnt a lesson from the past and had rectified its errors in a short period of time and will be decisive in handling all type of situation by establishing its eye from the sky. The brilliancy of Indian scientists lies in the designing of fixed geostationary satellite where the vision of its eye will not be lost on its homeland even for a micro/nanosecond. Thus the trick of camouflaging which India followed to hide itself from foreign satellites cannot be done by any foreign countries irrespective of the situation. Hence the supremacy in integrating the information of military forces will be ensured.  IRNSS has the plans and the ability to achieve both compatibility and interoperability with other GNSS operators through bi/multilateral meetings.  Therefore, IRNSS will ensure C4ISR (Command, Control, Computers, Communications, Intelligence, Surveillance and Reconnaissance). Hence it helps in integrating data fusion and integration management system, radar, infrared, space based surveillance ensuring a high level accuracy in modern warfare.

IRNSS Invincibility against Anti-satellite Missiles

Most importantly IRNSS satellites are placed in High Earth Orbit (HEO) at a height of 35,786 kilometres. It has strategic importance when considering anti-satellite missiles. It makes IRNSS out of range of solid-fuelled intercontinental missiles and makes it a more challenging task for liquid-fuelled launch vehicles[32] to reach this strategic height. At this height it can be easily traced by Indian government in order to take necessary actions as per the situation[33].

Technical Parameters

By looking at the number of satellites each GNSS system holds, along with coverage and spectrum of each GNSS, it is easy to understand the intelligence of Indian scientists in designing IRNSS. The following satellites have global coverage: GPS has 30 low earth orbit satellites; GLONASS has 24 Medium earth orbit satellites; Galileo plans to have 30 medium earth orbit satellites; COMPASS (Beidou-2) with 5 geo-stationary and 30 Medium Earth Orbit satellites[34]. On the other hand IRNSS achieves regional coverage with 7 geostationary satellites placing in HEO as a part of Phase-1. Phase-2 may add 3-5 geostationary and geosynchronous satellites in order extend its coverage in entire Asia with its intelligence and innovative thinking. Therefore, the position of the satellite becomes an advantage in providing the safety benefits such as vertical guidance in all weather conditions. The stationary position of the satellite reduces the blind spot, unlike circular approach of satellites. GAGAN provides benefits to the aviation sectors like navigational safety enhancement in all modes of transports, geodynamics, natural resources and land management[35]. Thus the advantages of IRNSS are numerous.

It proves India’s superiority in all scientific fields is ascending. To be precise we can say that India is growing and when it celebrates centennial of its independence she will be the master in all technology. Its indigenous innovation will serve the world’s needs.

IRNSS interoperability with Beidou-1 and COMPASS (Beidou-2)  

Significantly IRNSS’ coverage extends upto 1,500-2,000 km beyond India’s boundary, which lies between longitude 30° E to 130°E and latitude ±30°S to 50°N[36].  Therefore, it could eventually provide service to the SAARC countries including Afghanistan, Pakistan, Nepal, Bhutan, Bangladesh, Sri Lanka, Maldives and India as they come under the satellite’s coverage.

 This will make India to play a key role in the development of South Asia[37]. The profound importance of the satellite will help in developing good relations between India and its neighbouring countries. This will be achieved by ensuring the service of SPS as well as RS signals in aviation and other required fields for the development of the Asian region.

Map 4: IRNSS Coverage Area[38]


On May 15, 2015 India and China held bilateral talks in presence of Prime Minister Narendra Modi and Chinese Premier Li Keqiang. A new avenue of cooperation has been signed, notably the two sides welcomed the space cooperation mechanism and agreed to reinforce the cooperation in the field of satellite navigation[39]. Further, IRNSS have the capacity to integrate itself with other satellites like Beidou-1 and Compass (Beidou-2) satellite navigation system of China, so that it can empower the service. Remarkably the service of Beidou was utilized by Thailand, Laos and Pakistan. By interfacing itself with other regional technologies India can provide tremendous coverage to its homeland, and its neighbouring countries throughout Asia. The operational range of the Compass (Beidou-2) ranges will be from longitude 70°E to 140°E and latitude 5°N to 55°N with 5 geostationary satellites, 27 MEO (Medium Earth Orbit) satellites and 3 IGSO (Inclined Geosynchronous satellites). Through this COMPASS (Beidou-2) achieves a global coverage by 2020[40].  Therefore, by integrating the service, India could achieve its greatest height in the field of navigation.

Map 5: Beidou-1 Coverage area[41]


IRNSS is now becoming a milestone of Indian navigation system. It can make India self-reliant in technology under any circumstances.  Strategically, it can integrate the activities of military vehicles as per the operations and it will ensure C4ISR to a greater extent. Upcoming unmanned vehicles of India can be greatly monitored and directed via the service provided by IRNSS.  ISRO scientists added another gem to the crown of ‘India’s Indigenousness’ by producing IRNSS.  They proved their ability as master thinkers of science while upholding the legacy of their predecessors of the golden ancient era.


[1]  The Beginner’s Guide to Different Satellite Navigation Systems. Retrieved on May 03, 2015 from

[2]     GNSS and SBAS. Retrieved on May 05, 2015 from

[3]  IRNSS – An Indian Version of GPS. Retrieved on May 04, 2015 from

[4]  List of English Words derived from Sanskrit via Latin Greek Persian. Retrieved on May 06, 2015 from

[5] Kalidasa.   Retrieved on May 01, 2015 from

[6]  Meghdutam.

[7] Indian Regional Navigational Satellite System [IRNSS]. Retrieved on May 02, 2015 from

[8]  “Weapon of peace: How the CIA was fooled”. Retrieved on May 10, 2015 from

[9]  Quora, How did India manage to hide its nuclear test preps?. Retrieved on May 05, 2015 from on 05 May 2015.

[10] 1999 Kargil Conflict.  Retrieved on May 11, 2015 from

[11] Military Navigation. Retrieved on May 04, 2015 from

[12]  Indian State of Jammu and Kashmir. Retrieved on April 25, 2015 from

[13] How Kargil spurred India to design own GPS. Retrieved on May 05, 2015 from

[14] IRNSS. Retrieved on May 05, 2015 from

[15]  Satellites for Navigation. Retrieved on May 05, 2015 from

[16] A Literature Study of Various Satellite Navigation Systems with Reference to Their Signaling Scheme. Retrieved on May 14, 2015 from

[17] PSLV-C27 IRNSS-1D. Retrieved on May 11, 2015 from

[18] IRNSS – An Indian Version of GPS. Retrieved on May 11, 2015 from

[19]  Indian Regional Navigation Satellite System. Retrieved April 05, 2015 from

[20] Indian Regional Navigation Satellite System. Retrieved on May 15, 2015 from

[21] IRNSS Signal Plan.  Retrieved on May 12, 2015 from

[22]  Satellites for navigation.  Retrieved on May 03, 2015 from

[23]    A Look at GPS Alternatives. Retrieved on April 27, 2015 from

[24]  Indian Regional Navigation Satellite System (IRNSS): A Leap into the Final Frontier.  Retrieved on May 03, 2015 from

[25]  Indian Regional Navigation Satellite System Payload. Retrieved on May 07, 2015 from

[26] IRNSS (Indian Regional Navigational Satellite System).  Retrieved on May 15, 2015 from

[27] Ibid.,

[28]  Indian Regional Satellite Navigation System-  An Overview. Retrieved on May 10, 2015 from

[29]  IRNSS. Retrieved on May 03, 2015 from

[30] Indian Regional Navigation Satellite System (IRNSS). Retrieved on May 09, 2015 from

[31]  Move over GPS: Here’s why you should be thankful to ISRO for developing IRNSS. Retrieved on 19 May 2015 from

[32] Israeli Experts: Arrow-3 Could be Adapted for Anti-Satellite Role.   Retrieved on May 18, 2015 from

[33]Anti-satellite Tests in Space—The Case of China. Retrieved on May 12, 2015 from

[34] United Nations office for Outer Space Affairs.  Retrieved on May 15, 2015 from

[35]  Satellite Navigation Programme. Retrieved on May 18, 2015 from

[36]  India’s positioning satellite aims to serve South Asia. Retrieved on 19 May 2015 from

[37]  ISRO working on satellite for SAARC countries: Chairman. Retrieved on 19 May 2015 from

[38]  IRNSS now Navigation through and around India would be easier and precise. Retrieved on 19 May, 2015 from

[39]  Full text: Joint statement of India-China bilateral talks. Retrieved on 19 May 2015 from

[40]  Basic performance of BeiDou-2 navigation satellite system used in LEO satellites precise orbit determination. Retrieved on 19 May 2015 from

[41]  Beidou: Meet Star Wars – The Chinese Version. Retrieved on 19 May 2015 from

About the Author 


Vithiyapathy P. is a Research Officer at the Chennai Centre for China Studies and is associated with Center for Asia Studies . He has studied B.E in Computer Science. He pursued his M.A in Defence and Strategic Studies and M. Phil in Centre for South and Southeast Asia Studies from the University of Madras. His primary field of interests are maritime, foreign policy, defence and strategic analysis. The main empirical focus of his research is on South and Southeast Asia and the wider Asian region. He can be reached at Twitter: @Vithiyapathy

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