India's NAVIC satellite navigation system to rival US-made GPS

To ensure that strategic and crucial sectors are not dependent on US-made GPS, India today took a major step towards indigenisation as ISRO's regional positioning system 'NAVIC' will now rely on Indian atomic clocks.
ISRO's ISTRAC cell and the National Physical Laboratory have signed an MoU under which the latter will help authenticate precise timings for the space agency, crucial for its satellites, and also end its dependence on American GPS.
The NPL, an institute under the Council of Scientific and Industrial Research (CSIR), is one of oldest in the country, founded before India's independence, and provides high precision Indian Standard Time (IST), through its atomic clocks.

These atomic clocks are synchronised with the atomic clock of the International Bureau of Weights and Measures (BIPM), France, which provides the Universal Time Coordinated (UTC) to the world.
There are some 400 atomic clocks in the world and India has 4-5 of them. These clocks are so precise that the margin of error in their functioning is just of a second in 100 million years.
Such high precision timings, where nanoseconds also matter, are very crucial for ISRO's satellites.

The space agency is working to build its own Indian version of GPS - the NAVIC - and has launched its own Indian Regional Navigation Satellite System (IRNSS).

"The accuracy of satellite navigation system depends on the proper synchronisation of on-board clocks and at least four satellites are needed to know someone's position accurately," said V V Srinivasan, the Director of ISRO Telemetry and Command Network (ISTRAC).
ISRO also maintains its own atomic clocks, but the traceability for this was being provided by the GPS, which is linked to the BIPM in France.
Elucidating the significance of the development, ISRO scientists cited an instance during the Gulf War when the US deactivated the GPS system over the Middle East.
"The long-term plan is to emphasis on using NAVIC in India. For that, we cannot rely on the GPS. The MoU will put an end to our dependence on the GPS and rely on our indigenous services," an ISRO scientist said on condition of anonymity as he was not authorised to talk to the media.