ISRO’s new NavIC satellite

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The Indian Space Research Organisation (ISRO) launched the first of the second-generation satellites for its navigation constellation successfully.

NavIC (Navigation with Indian Constellation) is a regional navigation satellite system of India.
NavIC is erstwhile known as the Indian Regional Navigation Satellite System (IRNSS).
NavIC is designed with a constellation of 7 satellites, all launched by PSLV rockets.
Three satellites of the constellation are placed in geostationary orbit and the other 4 satellites are placed in inclined geosynchronous orbit.
NavIC offers two services: Standard Position Service (SPS) for civilian users and Restricted Service (RS) for strategic users.
NavIC satellites will broadcast SPS signals in L1, L5 and S bands after the addition of NVS-01.
RS signals will be broadcasted in L5 and S bands.

Atomic clock - Satellite-based positioning system determines the location of objects by using the atomic clocks on board.
The atomic clocks accurately measures the time it takes for a signal to travel to and back from it.
In 2018, ISRO started the launch of the replacement satellites after their onboard atomic clock failed and it stopped providing accurate location data.
Mission Life - IRNSS-1A which was launched into orbit in 2013, is almost defunct.
All the 3 oldest satellites in the constellation are close to the end of their 10-year mission lives.
At least three new satellites must be put into orbit to keep the seven-satellite constellation fully functional.
Signal Band - The L1 frequency is among the most commonly used in the Global Positioning System (GPS).
Earlier IRNSS used only L5 and S frequencies, this limits the interoperability with other global navigation satellite system (GNSS).

They are replacement satellite for the Indian Regional Navigation Satellite System.
The second generation satellites will replace satellites located at a geosynchronous orbit with additional features.
NVS series of satellites will sustain and augment the NavIC with enhanced features.
NVS-01 - It is the first of the second-generation satellites envisaged for NavIC services.
NVS-01 was launched by a Geosynchronous Satellite Launch Vehicle (GSLV) rocket.
It is the heaviest satellite in the constellation weighing 2,232 kg.

Mission Life - The second-generation satellites will also have a longer mission life of more than 12 years.
The existing satellites have a mission life of 10 years.
New band (L1) - The NVS series incorporates L1 band signals additionally to widen the services.
The existing satellites provide L5 and S frequency signals.
L1 signals increases the interoperability with other satellite-based global navigation systems.
It will increase the use of NavIC in wearable devices and personal trackers that use low-power, single-frequency chips.
Atomic clock - For the first time, an indigenous atomic clock will be flown in NVS-01.
The satellite will have a Rubidium atomic clock onboard, indigenously developed by Space Application Centre-Ahmedabad.

After the development of the user receivers, NavIC is used for practical public applications.
NavIC is in use for projects like public vehicle safety, power grid synchronisation, real-time train information systems, and fishermen’s safety.
Initiatives such as common alert protocol based emergency warning and unmanned aerial vehicles are in the process of adopting NavIC system.
The Ministry of Electronics and IT urging smartphone companies to make their handsets NavIC compatible.

There are four global satellite-based navigation systems
- The American GPS
- The Russian GLONASS
- The European Galileo
- The Chinese Beidou

Japan has a 4-satellite system that can augment GPS signals over the country, similar to India’s GAGAN.
India is the only country that has a regional satellite-based navigation system.
Accuracy - GPS signals are accurate up to around 20 metres whereas NavIC open signals will be accurate up to 5 metres and restricted signals will be even more accurate when fully operational.
Coverage - NavIC provides coverage over the Indian landmass and up to a radius of 1,500 km around it.
Consistency - NavIC uses satellites in high geo-stationery orbit which enables the satellite to look over the same region on Earth always.
Penetration - NavIC signals come to India at a 90-degree angle, making it easier for them to reach devices located even in congested areas, dense forests, or mountains.