What’s this magic?

I was traveling in Ooty almost a year ago and suddenly ended up in a dead-end alley following Google Maps directions. It took a lot of maneuvering on the mountains to get out of that narrow road and that got me thinking about how dependent we have become on this magic called GPS.

You may have been dazzled at times by how the Google Maps or Apple Maps application accurately guided you to a great but remote restaurant in an unknown city. You may also have been frustrated by the maps app misdirecting you sometimes in some places.

The clear-as-daylight fact is that we are increasingly becoming dependent on the GPS — Global Positioning System — technology. But do you really know or understand how GPS works?

GPS typically has 3 main components:

- Satellites

- Ground Stations

- Receivers

Satellites keep going around the Earth constantly beaming their location. The Ground Stations monitor and control the Satellite communications to identify their locations. Receivers (on your phones, cars, etc.) are constantly listening for the signals from the satellites.

When a receiver gets a signal from 4 or more satellites, that information is used for calculating the current 3D location of the receiver. The distance to each satellite estimates four crucial parameters:

- Earth latitude

- Earth longitude

- Elevation

- Time

Based on the parameters derived from the satellite signal locking, a GPS receiver calculates your position. For a 2D location, signals from 3 satellites are enough. This is the same working mechanism for the GPS receivers on your phone or in your car.

At present, GPS offers two levels of service:

a) Standard Positioning Service — which is used by 99.9% of the receivers

b) Precise Positioning Service — used only by special agencies like US Federal companies, Armed Forces, and the Governments and not available for Civilian use

There are 31 GPS satellites that are US-owned which complete a full revolution around the Earth every 12 hours. Then there are 24 GLONASS satellites that are owned by Russia, that complete an orbital movement every 11 hours because they are in a faster orbit around the Earth.

Not many people know that India has its own Global Positioning System called NaVIC (NaVigation with Indian Constellation). It has 7–8 satellites right now covering India and a region extending 1,500 km around it, with plans for further extension.

NaVIC-based trackers have been made compulsory on commercial vehicles in India. ISRO is planning to replace & upgrade some of these NAVIC satellites along with launching more satellites to a Middle Earth Orbit for enhanced positioning accuracy.

Given the current India-China political scenario, it is ironic that some consumer mobile phones of Chinese vendors with support for NaVIC have been available in the Indian market since the first half of 2020, and not many Indian-made phones.