UPSC Mains 2015 GS Paper 3 Q11: model answer
What do you understand by ‘Standard Positioning Systems’ and ‘Precision Positioning Systems’ in the GPS era? Discuss the advantages India perceives from its ambitious IRNSS programme employing just seven satellites.
What the question wants
Explain Standard and Precision Positioning Services in satellite navigation, and the benefits India sees in its seven-satellite IRNSS.
How to structure it
Two services, then IRNSS benefits.
- How satellite navigation works
- SPS vs PPS
- IRNSS design
- Benefits
- Issues
How to think it through
GNSS: receivers compute position from signals of four or more satellites. SPS: open civilian service, lower accuracy. PPS (RS in IRNSS): encrypted, for authorised/military users, higher accuracy and anti-jamming. IRNSS/NavIC: 7 satellites (3 GEO, 4 GSO), covers India + 1,500 km; accuracy better than 20 m (SPS); regional design so few satellites suffice. Benefits: strategic autonomy (Kargil 1999 GPS denial), disaster, fisheries, transport, timing for banking/grid, mobile phones (NavIC chips mandated). Issues: atomic clock failures, IRNSS-1H failed launch, NVS-02 orbit raising failure 2025; L1 band added in NVS series.
Model answer
During the Kargil war in 1999, India asked the US for GPS data over the battle zone and was refused. A country that depends on someone else's satellites for its soldiers' positions is not fully sovereign. That lesson produced the IRNSS, now called NavIC.
How satellite navigation works
- A receiver measures the time signals take from at least four satellites and calculates its position.
Standard and Precision Positioning
- Standard Positioning Service (SPS): an open, free signal for civilian users, such as phones, cars and ships.
- Precision Positioning Service (PPS): an encrypted signal for authorised users like the armed forces; more accurate and resistant to jamming and spoofing.
- In NavIC these are called the Standard Positioning Service and the Restricted Service.
Why seven satellites are enough
- NavIC is regional, not global: it covers India and about 1,500 km around it.
- Three geostationary and four geosynchronous satellites stay over the region all the time.
- Accuracy is better than 20 metres for civilians.
Benefits India sees
- Strategic autonomy in war and crisis.
- Disaster management and alerts to fishermen at sea.
- Transport: vehicle tracking and fleet management.
- Precise timing for banks, power grids and telecom.
- NavIC chips in mobile phones and the Indian space industry.
Issues
- Atomic clock failures on early satellites.
- Replacement launches have faced setbacks, such as the NVS-02 orbit problem in 2025.
NavIC is small in size but large in what it means: India's own position, measured by India.
Draw: India at the centre with seven satellites above it and a 1,500 km coverage ring.
Keywords, cases and data to drop in
GNSS, SPS, PPS, Restricted Service, IRNSS/NavIC, 3 GEO + 4 GSO, 1,500 km, 20 m accuracy, Kargil 1999, atomic clocks, NVS series, L1 band.
Where most answers lose marks
- Confusing NavIC with GPS-aided GAGAN, which only improves GPS accuracy for aviation.
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Question text as printed in the official UPSC Civil Services (Main) question paper. The model answer is original Battle IAS work; use it to learn structure, not to memorise.
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