Developing Indigenous Atomic Clock on NAVIC System (Download PDF)


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Atomic clocks on 1st satellite IRNSS-1A of NAVIC is indigenously built satellite system. It will be used in navigation satellites to measure precise location data. Minimum 4 working satellites were sufficient for proper functioning of navigation system.

Image of Indian Regional Navigation Satellite System

Image of Indian Regional Navigation Satellite System

Image of Indian Regional Navigation Satellite System

Foreign Clocks

  • 7 navigation satellites, which are launched earlier as part of Indian Regional Navigation Satellite System (IRNSS) or Navigation w/Indian Constellation (NaVIC). They have 3 imported Rubdium atomic clocks each.

  • 1 of 3 crucial rubidium clock on IRNSS-1A spacecraft failed 6 months ago while other 2 failed subsequently.

  • NAVIC is constellation of 7 satellites in geosynchronous orbit & 2 backup satellites on ground. Each satellite consists of 3 atomic clocks. There are total 27 atomic clock in NAVIC.

  • Default satellite would replaced by one of back-up satellite 1H.

  • Rest of satellite were functioning well in terms of performing well in terms of performing its core function of providing accurate position, navigation & time.

Highlights of ISRO’s Atomic Clock

  • Atomic clock is developed by Ahmedabad-based Space Applications Centre (SAC). It is currently undergoing a series of qualification tests.

  • Atomic clock will be used in experimental navigation satellite to test its accuracy & durability in space.

  • W/development of atomic clock, ISRO has become one of few space organisations in world that are capable to develop this highly sophisticated technology.

Background on Atomic Clocks:

  • Navigation satellite is fixed w/3 atomic clocks. Besides atomic clocks, navigation satellite has crystal clocks but they are not as accurate as atomic clocks.

  • Time difference b/w atomic clocks of diff. satellites positioned at diff. orbits is used to measure accurate positioning of navigation receiver or object on Earth.

  • If atomic clock malfunctions, time difference calculated b/w it & other clocks comes out to be inaccurate, thus, rendering inaccurate positioning of object.

  • If all 3 atomic clocks of satellite show error, then space agency needs to launch back-up satellite w/new atomic clocks.

  • As 9 of 21 atomic clocks used in already launched 7 navigation satellites are showing error, therefore, ISRO planned to launch four backup navigation satellites to keep NaVIC effective.

  • These backup satellites, which are expected to have indigenous atomic clocks as well, will add buffer to the country’s GPS system.


  • Navigation w/Indian Constellation (NaVIC) known as Indian Regional Navigation Satellite System (IRNSS).

  • It is autonomous regional satellite navigation system.

  • It was built by India to provide accurate real-time positioning & timing services over India & region extending to 1500 km.

  • NAVIC system will consist of constellation of 3 satellites in Geostationary orbit (GEO), 4 satellites in Geosynchronous orbit (GSO) & 2 satellites on ground as stand-by.

  • 7 constellations of satellites: IRNSS-1A, IRNSS-1B, IRNSS-1C, IRNSS-1D, IRNSS-1E, IRNSS-1F, & IRNSS-1G.

  • Satellites were developed to give precise information on position, navigation & time (PNT) of objects or persons to users on ground, sea. & Air


  • IRNSS-1A is 1st navigational satellite of Indian Regional Navigation Satellite System (IRNSS) series of satellites.

  • Satellite was launched on 1st July 2013 at cost of USD 19 million.

  • It provides data similar to Global Positioning System (GPS) used by US.

Atomic Clock

  • Atomic clock is extremely accurate clock device. It uses vibrations of atomic or molecular system like caesium or ammonia for its timekeeping element.
  • Atomic clocks are most accurate time & frequency standards known & used as primary standards for international time distribution services to control wave frequency of television broadcasts & in global navigation satellite systems like GPS.
  • Indian Space Research Organisation
  • ISRO is space agency of GoI headquartered in Bangalore.
  • ISRO was established in 1969.
  • Objective of ISRO is to use space technology & its application to various national tasks.

- Published/Last Modified on: August 7, 2018

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