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Indian Regional Navigation Satellite System

Topic: Astronomy

 From HandWiki - Reading time: 14 min
Short description: Satellite navigation system

Navigation with Indian Constellation (NAVIC)
Indian Regional Navigation Satellite System (IRNSS)
Country/ies of originIndia
Operator(s)ISRO
TypeMilitary, Commercial
StatusOperational
CoverageRegional (up to 1,600 km from borders)
Accuracy10 m or 33 ft (public)
0.1 m or 3.9 in (encrypted)
Constellation size
Total satellites7
Satellites in orbit7 (IRNSS 1I launched completing the series)
Total launches9
Orbital characteristics
Regime(s)High Earth
Orbital height36,000 km (22,000 mi)[1]
Other details
Cost₹22.46 billion (US$315 million), to March 2017[2]
Geodesy
Azimutalprojektion-schief kl-cropped.png
Fundamentals
Concepts
Technologies
Standards (history)
NGVD 29 Sea Level Datum 1929
OSGB36 Ordnance Survey Great Britain 1936
SK-42 Systema Koordinat 1942 goda
ED50 European Datum 1950
SAD69 South American Datum 1969
GRS 80 Geodetic Reference System 1980
ISO 6709 Geographic point coord. 1983
NAD 83 North American Datum 1983
WGS 84 World Geodetic System 1984
NAVD 88 N. American Vertical Datum 1988
ETRS89 European Terrestrial Ref. Sys. 1989
GCJ-02 Chinese obfuscated datum 2002
Geo URI Internet link to a point 2010

The Indian Regional Navigation Satellite System (IRNSS), with an operational name of NAVIC (acronym for NAVigation with Indian Constellation; also, nāvik 'sailor' or 'navigator' in Sanskrit, Hindi, and many other Indian languages),[3] is an autonomous regional satellite navigation system that provides accurate real-time positioning and timing services.[4] It covers India and a region extending 1,500 km (930 mi) 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 to the 50th parallel north and the 30th meridian east to the 130th meridian east, 1,500–6,000 km (930–3,730 mi) beyond borders.[5] The system currently consists of a constellation of seven satellites,[1][6] with two additional satellites on ground as stand-by.[7]

The constellation is in orbit as of 2018, and the system was expected to be operational from early 2018[8][9] after a system check.[10] 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 is planned to become available for civilian use in the first half of 2020.[11]

There are plans to expand the NAVIC system by increasing its constellation size from 7 to 11.[12]

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 it was dependent on the American Global Positioning System (GPS) during the Kargil War.[13] The Indian government approved the project in May 2013.

Development

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.[14] 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 a 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.[15]

The total cost of the project was expected to be ₹14.2 billion (US$199 million), with the cost of the ground segment being ₹3 billion (US$42 million), each satellite costing ₹1.5 billion (US$21 million) and the PSLV-XL version rocket costing around ₹1.3 billion (US$18 million). The planned seven rockets would have involved an outlay of around ₹9.1 billion (US$128 million).[7][16][17]

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, to March 2017, at ₹22.46 billion (US$315 million)[2]

The NAVIC signal was released for evaluation in September 2014.[18]

NAVIC is planned to be available for civilian use in the first half of the year 2020, after Qualcomm and Indian Space Research Organisation signed an agreement. Qualcomm has developed mobile-phone chips which can receive signals from NAVIC.[11][19]

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,[20] and India also launched 3 new satellites to supplement this.[21]

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.[22][23] IRNSS-1B was launched on 4 April 2014 on-board PSLV-C24 rocket. The satellite has been placed in geosynchronous orbit.[24] IRNSS-1C was launched on 16 October 2014,[25] IRNSS-1D on 28 March 2015,[26] IRNSS-1E on 20 January 2016,[27] IRNSS-1F on 10 March 2016 and IRNSS-1G was launched on 28 April 2016.[28]

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 4th stage of the rocket.[29] IRNSS-1I was launched on 11 April 2018 to replace it.[30][31]

System description

Coverage of NAVIC

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 32.5° E, 83° E, and 131.5° E longitude, approximately 36,000 km (22,000 mi) above earth surface. Remaining four satellites are in inclined geosynchronous orbit (GSO). Two of them cross equator at 55° E and two at 111.75° E.[32][33] The four GSO satellites will appear to be moving in the form of an "8".[34]

Ground segment

Ground Segment is responsible for the maintenance and operation of the IRNSS constellation. The Ground segment comprises:[32]

  • 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)
Rendering of an IRNSS Series 1 satellite

The INC established at Byalalu performs remote operations and data collection with all the ground stations. 14 IRIMS are currently operational and are supporting IRNSS operations. CDMA 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 ns (2.0×10−9 s) (2 sigma) w.r.t UTC. Laser ranging is being carried out with the support of ILRS stations around the world. Navigation Software is operational at INC since 1 August 2013. All the navigation parameters viz. satellite ephemeris, clock corrections, integrity parameters and secondary parameters viz. iono-delay corrections, time offsets w.r.t UTC and other GNSS, 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. 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.[32][35]

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)[36]. 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 frequency (2–4 GHz) 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.[37]

Accuracy

The system is intended to provide an absolute position accuracy of better than 10 metres (33 ft) throughout Indian landmass and better than 20 metres (66 ft) in the Indian Ocean as well as a region extending approximately 1,500 km (930 mi) around India.[38] The Space Applications Centre in 2017 said NAVIC will provide standard positioning service to all users with a position accuracy up to 5 m.[37] The GPS, for comparison, had a position accuracy of 20–30 m.[39] Unlike GPS which is dependent only on L-band, NAVIC has dual frequency (S and L bands). When low frequency signal travels through atmosphere, its velocity changes due to atmospheric disturbances. US banks on 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 dual frequency (S and L bands). Therefore, NavIC is not dependent on any model to find the frequency error and is more accurate than GPS.[40]

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 in inclined geosynchronous orbit (IGSO). All satellites launched or proposed for the system are as follows:

IRNSS-1 series satellites[32][41]
Satellite SVN PRN Int. Sat. ID NORAD ID Launch Date Launch Vehicle Orbit Status Remarks
IRNSS-1A I001 I01 2013-034A 39199 PSLV-XL-C22 Geosynchronous (IGSO) / 55°E, 29° inclined orbit Failed in orbit Atomic clocks failed.[42][43]
IRNSS-1B I002 I02 2014-017A 39635 PSLV-XL-C24 Geosynchronous (IGSO) / 55°E, 29° inclined orbit Operational
IRNSS-1C I003 I03 2014-061A 40269 PSLV-XL-C26 Geostationary (GEO) / 83°E, 5° inclined orbit Operational
IRNSS-1D I004 I04 2015-018A 40547 PSLV-XL-C27 Geosynchronous (IGSO) / 111.75°E, 31° inclined orbit Operational
IRNSS-1E I005 I05 2016-003A 41241 PSLV-XL-C31 Geosynchronous (IGSO) / 111.75°E, 29° inclined orbit Operational
IRNSS-1F I006 I06 2016-015A 41384 PSLV-XL-C32 Geostationary (GEO) / 32.5°E, 5° inclined orbit Operational
IRNSS-1G I007 I07 2016-027A 41469 PSLV-XL-C33 Geostationary (GEO) / 129.5°E, 5.1° inclined orbit Operational
IRNSS-1H PSLV-XL-C39 Launch Failed The payload fairing failed to separate and satellite could not reach the desired orbit.[29][44] It was meant to replace defunct IRNSS-1A.[42][12]
IRNSS-1I I009 2018-035A 43286 PSLV-XL-C41 Geosynchronous (IGSO) / 55°E, 29° inclined orbit Operational [45]
IRNSS-1J Geosynchronous (IGSO), 42° inclined orbit Planned

[46][47]

IRNSS-1K Geosynchronous (IGSO), 42° inclined orbit Planned

[46][47]

IRNSS-1L Geosynchronous (IGSO), 42° inclined orbit Planned

[46][47]

IRNSS-1M Geosynchronous (IGSO), 42° inclined orbit Planned

[46][47]

IRNSS-1N Geosynchronous (IGSO), 42° inclined orbit Planned

[46][47]

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.[48][49] 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.[50] ISRO reported it had replaced the atomic clocks in the two standby satellites, IRNSS-1H and IRNSS-1I., in June 2017[12] The subsequent launch of IRNSS-1H, as a replacement for IRNSS-1A, was unsuccessful when PSLV-C39 mission failed on 31 August 2017.[12][51] The second standby satellite, IRNSS-1I, was successfully placed into orbit on 12 April 2018.[45]

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,[12] in May 2018 a failure of a further 4 clocks was reported, taking the count to 9 of the 24 in orbit.[52]

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.[12]

Future developments

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.[53] These additional four satellites will be made during 12th FYP and will be launched in the beginning of 13th FYP in geosynchronous orbit of 42° inclination.[47][54] Also, the development of space-qualified Indian made atomic clocks was initiated,[55] along with a study and development initiative for an all optical atomic clock (ultra stable for IRNSS and deep space communication).[56][53]

IRNSS-1J, IRNSS-1K, IRNSS-1L, IRNSS-1M and IRNSS-1N are next batch of spacecrafts in development.[46]

Global Indian Navigational System (GINS)

Study and analysis for Global Indian Navigational System (GINS) was initiated as part of the technology and policy initiatives in the 12th FYP (2012–17).[56] 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.[57]

See also

References

  1. ↑ 1.0 1.1 "Orbit height and info". Archived from the original on 30 December 2015. https://web.archive.org/web/20151230083702/http://www.sac.gov.in/SACSITE/IRNSS-1A.html. 
  2. ↑ 2.0 2.1 https://www.geospatialworld.net/blogs/cag-pulls-up-isro-on-navic-delays-cost-overruns/
  3. ↑ "IRNSS-1G exemplifies ‘Make in India’, says PM". The Statesman. 28 April 2016. Archived from the original on 23 September 2016. https://web.archive.org/web/20160923005239/http://www.thestatesman.com/mobi/news/latest-headlines/irnss-1g-exemplifies-make-in-india--says-pm/139068.html. Retrieved 28 April 2016. 
  4. ↑ "Satellites are in the sky, but long way to go before average Indians get Desi GPS". https://timesofindia.indiatimes.com/india/satellites-are-in-the-sky-but-long-way-to-go-before-average-indians-get-desi-gps/articleshow/64506628.cms. 
  5. ↑ "IRNSS Programme - ISRO" (in en). https://www.isro.gov.in/irnss-programme. 
  6. ↑ "IRNSS details". Archived from the original on 10 March 2016. https://web.archive.org/web/20160310163951/http://www.isro.gov.in/irnss-programme/towards-self-reliance-navigation-irnss. 
  7. ↑ 7.0 7.1 "Isro to launch 5th navigation satellite on Jan 20, first in 2016". http://www.hindustantimes.com/india/isro-starts-countdown-to-launch-fifth-navigation-satellite-irnss-1e/story-qSv6U8T8dT4pRThRHc3VIO.html. 
  8. ↑ http://www.ibtimes.co.in/indias-own-gps-irnss-navic-made-by-isro-go-live-early-2018-728409
  9. ↑ "Isro's PSLV-C32 places India's sixth navigation satellite IRNSS-1F in orbit". Times of India. http://timesofindia.indiatimes.com/india/Isros-PSLV-C32-places-Indias-sixth-navigation-satellite-IRNSS-1F-in-orbit/articleshow/51343491.cms. 
  10. ↑ "ISRO puts seventh and final IRNSS navigation satellite into orbit". Times of India. http://tech.firstpost.com/news-analysis/isro-puts-seventh-and-final-irnss-navigation-satellite-into-orbit-311968.html. 
  11. ↑ 11.0 11.1 "After Isro-Qualcomm pact, NaVIC-compatible mobiles, navigation devices to hit market next year" (in en). 16 October 2019. https://timesofindia.indiatimes.com/india/after-isro-qualcomm-pact-navic-compatible-mobiles-navigation-devices-to-hit-market-next-year/articleshow/71606495.cms. 
  12. ↑ 12.0 12.1 12.2 12.3 12.4 12.5 IANS (2017-06-10). "Navigation satellite clocks ticking; system to be expanded: ISRO". The Economic Times. https://economictimes.indiatimes.com/news/science/navigation-satellite-clocks-ticking-system-to-be-expanded-isro/articleshow/59082657.cms. 
  13. ↑ Srivastava, Ishan (5 April 2014). "How Kargil spurred India to design own GPS". The Times of India. http://timesofindia.indiatimes.com/home/science/How-Kargil-spurred-India-to-design-own-GPS/articleshow/33254691.cms. Retrieved 9 December 2014. 
  14. ↑ "ISRO opens navigation centre for satellite system". Zeenews.com. 2013-05-28. http://zeenews.india.com/news/space/isro-opens-navigation-centre-for-satellite-system_851487.html. Retrieved 30 June 2013. 
  15. ↑ "India Making Strides in Satellite Technology". Defence News. Archived from the original on 6 June 2013. https://web.archive.org/web/20130606194638/http://www.defencenews.in/defence-news-internal.asp?get=old&id=239. Retrieved 26 July 2012. 
  16. ↑ "India's first ever dedicated navigation satellite launched". DNA India. 2 July 2013. http://www.dnaindia.com/scitech/1855830/report-india-s-first-ever-dedicated-navigation-satellite-launched. Retrieved 24 July 2013. 
  17. ↑ "India's first dedicated navigation satellite placed in orbit". NDTV. 2 July 2013. http://www.ndtv.com/article/india/india-s-first-dedicated-navigation-satellite-placed-in-orbit-386649. Retrieved 24 July 2013. 
  18. ↑ "IRNSS Signal in Space ICD Released". gpsworld.com. 25 September 2014. http://gpsworld.com/irnss-signal-in-space-icd-released/. Retrieved 7 September 2016. 
  19. ↑ "NavIC support in upcoming Mobile, Automotive and IoT Platforms is poised to deliver superior Location-Based services to India's Industries and Technology Ecosystem Through Qualcomm". Indian Space Research Organisation. October 14, 2019. https://www.isro.gov.in/update/14-oct-2019/navic-support-upcoming-mobile-automotive-and-iot-platforms-poised-to-deliver. Retrieved October 19, 2019. 
  20. ↑ S. Anandan (10 April 2010). "Launch of first satellite for Indian Regional Navigation Satellite system next year". Beta.thehindu.com. http://www.thehindu.com/sci-tech/article393892.ece. Retrieved 2010-12-30. 
  21. ↑ H. Pathak. "3 Satellites To Be Launched By ISRO". Archived from the original on 17 April 2011. https://web.archive.org/web/20110417015013/http://informationmadness.com/technology/tech-tips/3684-3-satellites-to-be-launched-by-isro-on-20th-april.html. 
  22. ↑ "ISRO's Future programme". ISRO. http://www.isro.org/scripts/futureprogramme.aspx#Satellite. Retrieved 18 May 2013. 
  23. ↑ "Countdown begins for PSLV-C22 launch". thehindubusinessline.com. http://www.thehindubusinessline.com/news/countdown-begins-for-pslvc22-launch/article4863108.ece. Retrieved 2013-06-29. 
  24. ↑ "Isro successfully launches navigation satellite IRNSS-1B". Times Of India. http://timesofindia.indiatimes.com/india/Isro-successfully-launches-navigation-satellite-IRNSS-1B/articleshow/33240651.cms. Retrieved 4 April 2014. 
  25. ↑ "ISRO puts India’s Navigation satellite IRNSS 1B into orbit". IANS. news.biharprabha.com. http://news.biharprabha.com/2014/04/isro-puts-second-irnss-navigation-satellite-into-orbit/. Retrieved 4 April 2014. 
  26. ↑ "India successfully launches IRNSS-1D, fourth of seven navigation satellites – Times of India". indiatimes.com. http://timesofindia.indiatimes.com/india/India-successfully-launches-IRNSS-1D-fourth-of-seven-navigation-satellites/articleshow/46727095.cms. Retrieved 7 September 2016. 
  27. ↑ "India launches 5th navigation satellite IRNSS-1E powered by PSLV rocket". http://www.hindustantimes.com/india/india-launches-5th-navigation-satellite-irnss-1e-powered-by-psl-rocket/story-iQcSrv7tV5sL3nfU49kLII.html. 
  28. ↑ Narasimhan, T. E.. "India gets its own GPS with successful launch of 7th navigation satellite". business-standard.com. http://www.business-standard.com/article/current-affairs/india-gets-its-own-gps-with-successful-launch-of-7th-navigation-satellite-116042800308_1.html. Retrieved 7 September 2016. 
  29. ↑ 29.0 29.1 "ISRO says launch of navigation satellite IRNSS-1H unsuccessful". The Economic Times. 2017-08-31. http://economictimes.indiatimes.com/news/science/isros-irnss-1h-launch-a-big-leap-for-private-sector-in-space/articleshow/60309043.cms. 
  30. ↑ "IRNSS-1I". Indian Space Research Organisation. https://www.isro.gov.in/Spacecraft/irnss-1i. Retrieved October 19, 2019. 
  31. ↑ "PSLV-C41/IRNSS-1I". Indian Space Research Organisation. April 12, 2018. https://www.isro.gov.in/launcher/pslv-c41-irnss-1i. Retrieved October 19, 2019. 
  32. ↑ 32.0 32.1 32.2 32.3 "IRNSS". http://www.isac.gov.in/navigation/irnss.jsp. 
  33. ↑ "First IRNSS satellite by December". Magazine article. Asian Surveying and Mapping. 5 May 2009. http://www.asmmag.com/news/first-irnss-satellite-by-december-. Retrieved 2009-05-05.  [|permanent dead link|dead link}}]
  34. ↑ "How Kargil spurred India to design own GPS". The Times of India. 5 April 2014. http://timesofindia.indiatimes.com/home/science/How-Kargil-spurred-India-to-design-own-GPS/articleshow/33254691.cms. Retrieved 28 April 2016. 
  35. ↑ K. Radhakrishnan (29 December 2013). "Mars and more, final frontier". Deccan Chronicle. http://www.deccanchronicle.com/131229/commentary-sunday-chronicle/article/mars-and-more-final-frontier. Retrieved 28 April 2016. 
  36. ↑ https://www.isro.gov.in/sites/default/files/irnss_sps_icd_version1.1-2017.pdf
  37. ↑ 37.0 37.1 "Indian ‘GPS’ for public use by year-end – Times of India". The Times of India. http://timesofindia.indiatimes.com/city/ahmedabad/indian-gps-for-public-use-by-year-end/articleshow/57470942.cms. 
  38. ↑ A. Bhaskaranarayana Director SCP/FMO & Scientific Secretary Indian Space Research Organisation – Indian IRNSS and GAGAN
  39. ↑ "India’s desi GPS ‘NavIC’ all set to navigate you". https://timesofindia.indiatimes.com/india/indias-desi-gps-navic-all-set-to-navigate-you/articleshow/64639096.cms. 
  40. ↑ http://timesofindia.indiatimes.com/home/science/get-ready-indias-own-gps-set-to-hit-the-market-early-next-year/articleshow/58876680.cms
  41. ↑ "IGS MGEX NAVIC" (in en). http://mgex.igs.org/IGS_MGEX_Status_IRNS.php. 
  42. ↑ 42.0 42.1 Mukunth, Vasudevan. "3 Atomic Clocks Fail Onboard India's 'Regional GPS' Constellation" (in en-GB). https://thewire.in/103934/atomic-clock-rubidium-irnss/. 
  43. ↑ D.S., Madhumathi. "Atomic clocks on indigenous navigation satellite develop snag" (in en). The Hindu. http://www.thehindu.com/news/national/Atomic-clocks-on-indigenous-navigation-satellite-develop-snag/article17114134.ece. 
  44. ↑ "IRNSS-1H launch unsuccessful, says ISRO" (in en-US). The Indian Express. 2017-08-31. http://indianexpress.com/article/technology/science/irnss-1h-launch-unsuccessful-says-isro-4822677/. 
  45. ↑ 45.0 45.1 "India completes NavIC constellation with 7th satellite - Times of India". The Times of India. https://timesofindia.indiatimes.com/india/india-completes-navic-constellation-with-7th-satellite/articleshow/63721895.cms. 
  46. ↑ 46.0 46.1 46.2 46.3 46.4 46.5 "Annual Report of Department of Space 2018-19". 28 May 2019. https://www.isro.gov.in/sites/default/files/annualreport2018-19.pdf. 
  47. ↑ 47.0 47.1 47.2 47.3 47.4 47.5 "The Interoperable Global Navigation Satellite Systems Space Service Volume". pp. 62, 95. https://www.unoosa.org/res/oosadoc/data/documents/2018/stspace/stspace75_0_html/st_space_75E.pdf. 
  48. ↑ "SpectraTime to Supply Atomic Clocks to IRNSS | Inside GNSS" (in en). http://www.insidegnss.com/node/789. 
  49. ↑ "Spectratime Awarded Contract To Supply Rubidium Space Clocks To IRNSS". http://www.spacedaily.com/reports/Spectratime_Awarded_Contract_To_Supply_Rubidium_Space_Clocks_To_IRNSS_999.html. 
  50. ↑ D.S., Madhumathi. "Atomic clocks on indigenous navigation satellite develop snag" (in en). The Hindu. http://www.thehindu.com/news/national/Atomic-clocks-on-indigenous-navigation-satellite-develop-snag/article17114134.ece. 
  51. ↑ "India’s 'GPS’ Remains Unfinished". Wayback Machine. Archived from the original on 26 January 2018. https://web.archive.org/web/20180126214443/https://thewire.in/173088/irnss-isro-pslv-c39-spectratime-atomic-clocks-space-debris/. Retrieved 26 January 2018. 
  52. ↑ D.s, Madhumathi (2018-05-05). "ISRO’s clock to prop up India’s own GPS" (in en-IN). The Hindu. ISSN 0971-751X. https://www.thehindu.com/news/national/isros-clock-to-prop-up-indias-own-gps/article23787959.ece. 
  53. ↑ 53.0 53.1 "Five Year Plan". Department of Space 12th FYP: 96. October 2011. http://www.dst.gov.in/sites/default/files/14-wg_dos2905-report.pdf. 
  54. ↑ "12th Five Year Plan report, Department of Space, DST". http://www.dst.gov.in/sites/default/files/14-wg_dos2905-report.pdf#page=52. 
  55. ↑ "ISRO to test space robustness of indigenous atomic clocks this December" (in en-IN). 2018-05-16. https://indianexpress.com/article/india/isro-to-test-space-robustness-of-indigenous-atomic-clocks-this-december/. 
  56. ↑ 56.0 56.1 http://www.dst.gov.in/sites/default/files/14-wg_dos2905-report.pdf
  57. ↑ "Global Indian Navigation system on cards" (in en). The Hindu Business Line. 2010-05-14. http://www.thehindubusinessline.com/todays-paper/tp-economy/global-indian-navigation-system-on-cards/article991761.ece. 

Footnotes

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

External links




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