NavIC launch: why regional navigation system matters

Contact Counsellor

Last Updated30/05/2023

The Indian Space Research Organisation (ISRO) will launch the first of the second-generation satellites for its navigation constellation today.
The 2,232 kg satellite (heaviest in the constellation) will be launched by a GSLV rocket that will lift off from Sriharikota on the mission that will last for a little over 18 minutes.

Each of the seven satellites currently in the Indian Regional Navigation Satellite System (IRNSS) constellation (NavIC) weighed much less — around 1,425 kg — at liftoff.
They all rode the lighter PSLV, ISRO’s workhorse launch rocket.
The last IRNSS satellite, IRNSS-1I was launched in April 2018 to replace an older, partially defunct satellite in the constellation.
- ISRO’s ninth satellite for the NavIC constellation
- But it is considered to be the eighth as the IRNSS-1H — launched eight months earlier in August 2017 was lost after the heat shield of the payload failed to open on time.

Much heavier than earlier satellites: The new second-generation satellite NVS-01, the first of ISRO’s NVS series of payloads is heavier.
Atomic clock: The satellite will have a Rubidium atomic clock onboard, developed by Space Application Centre-Ahmedabad - a technology which only a few countries possess.
L1 signals for better use in wearable devices: The II generation satellites will send signals in L1 - most commonly used in the GPS (besides L5 and S frequency signals provided by existing satellites) increasing interoperability with other satellite-based navigation systems.
Longer mission life: The new satellites will also have a longer mission life of more than 12 years. The existing satellites have a mission life of 10 years.

Existing satellites stopped providing location data after their onboard atomic clocks failed - so, a replacement satellite was launched in 2018.
A satellite-based positioning system determines the location of objects by accurately measuring the time it takes for a signal to travel to and back from it using the atomic clocks on board.
Failure of clocks means the satellites are no longer able to provide accurate locations.
Currently, only four IRNSS satellites are able to provide location services.
The other satellites can only be used for messaging services like providing disaster warnings or potential fishing zone messages for fishermen.

Second major concern, besides the failing atomic clocks.
IRNSS-1A was launched into orbit on July 1, 2013, and the 1B and 1C satellites were launched in the following year.
1A is almost defunct; the failed 1H mission of 2018 was intended to replace this satellite and all the three 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, ISRO officials said.

NavIC is in use for projects like public vehicle safety, power grid synchronisation, real-time train information systems, and fishermen’s safety.
Other upcoming initiatives (such as) common alert protocol based emergency warning, time dissemination, geodetic network, unmanned aerial vehicles are in the process of adopting NavIC system.
Some cell phone chipsets such as the ones built by Qualcomm and MediaTek integrated NavIC receivers in 2019.
The Ministry of Electronics and IT is in talks with smartphone companies to urge them to make their handsets NavIC compatible.

India is the only country that has a regional satellite-based navigation system.
There are 4 global satellite-based navigation systems — the American GPS, the Russian GLONASS, the European Galileo, and the Chinese Beidou.
Japan has a four-satellite system that can augment GPS signals over the country, similar to India’s GAGAN (GPS Aided GEO Augmented Navigation).

Once fully operational — with ground stations outside India for better triangulation of signals — NavIC open signals will be accurate up to 5 metres and restricted signals will be even more accurate.
- GPS signals by contrast are accurate up to around 20 metres.
NavIC provides coverage over the Indian landmass and up to a radius of 1,500 km around it.
In this region, NavIC signals will likely be available in even hard-to-reach areas.
Unlike GPS, NavIC uses satellites in high geo-stationery orbit — the satellites move at a constant speed relative to Earth, so they are always looking over the same region on Earth.
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.
- GPS signals are received over India at an angle.