Revision summary
Foreign GPS-type systems can be limited in a crisis, so India needs a regional grid it controls. NavIC covers India and a belt of about 1,500 km around it, including nearby seas. Receivers use satellite time delays to fix position; SPS is civil and a restricted service is authorised. Tropical ionosphere is handled better with more than one frequency. Public and defence users gain backup when chips read NavIC with other GNSS.
Model answer
Copper italics in this answer — like this — are the key facts. Each one is unpacked in the Facts & figures rail.
Introduction
IRNSS, named NavIC, is India’s own regional satellite navigation grid. It is needed because ships, aircraft, phones, and the armed forces cannot depend only on a foreign GPS when the signal can be denied or degraded.
Body
Why India needs its own system
- GPS, GLONASS, Galileo, and BeiDou are controlled by other states; in a crisis they can limit accuracy or cut civil access over a theatre.
- A regional system covering India and about 1,500 km around it serves the mainland, the island territories, and the nearby seas where most Indian shipping and aviation move.
- Disaster warning, rail and road tracking, and survey of mines and forests need a signal that New Delhi can keep available in monsoon and in conflict.
- Space-based navigation is also a mark of strategic autonomy, like a national map grid, once the country has launchers and atomic clocks in orbit.
How it helps in navigation
- A constellation of geostationary and geosynchronous satellites broadcasts time and orbit data; a receiver compares delays from several satellites and computes latitude, longitude, and altitude.
- Standard Positioning Service is open for civilian use; a restricted service is meant for authorised strategic users with higher integrity.
- Dual frequencies, including an S-band channel, help reduce ionospheric error over the tropical Indian belt, where GPS L1 alone can wander.
- With a matching ground segment of ranging stations and a control centre, NavIC can guide fishing craft beyond the horizon, time-stamp power grids, and support missile and troop movement without a foreign key.
- Apps and chipsets that read NavIC along with GPS give a backup when one constellation is weak in cities or in mountain shadow.
Way forward
- Put NavIC in more phones, AIS sets, and aircraft boxes so the public service is not only a satellite fact.
- Keep clocks, spares in orbit, and ground stations healthy, because a navigation grid fails if time is wrong.
Flow diagram
flowchart TD N[NavIC IRNSS] --> C[India plus 1500 km] F[Foreign GNSS risk] --> N N --> P[Time range position] P --> U[Ships phones survey defence]
Conclusion
IRNSS is needed for sovereign, regional coverage when foreign GNSS can be limited. It helps navigation by giving Indian users a timed satellite fix for civil and restricted work from the coast to the high Himalaya.
Quick related
Students also ask
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Why is India taking keen interest in the Arctic region?
Next question on this syllabus topic (2018 · Q5). View answer →
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Does NavIC replace GPS for every Indian user?
Not yet. Many devices still rely on GPS. NavIC is the sovereign regional layer and a backup when chips support it.
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Is this only a military project?
No. Fishing, disaster alerts, survey, and timing of civilian networks are designed uses along with authorised defence use.
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