How GPS work?

The Global Positioning System (GPS) we all know is called “Navstar” which is own by the US Department of Defense (DOD). Other countries also have their own GPS system like Russia has GLONASS, China has COMPASS and India has IRNSS but most of the device which we are using is NAVSTAR based GPS system.

Working of GPS we all know right? It’s a play between the receiver (our GPS device) and transmitter (GPS Satellites) with accuracy influenced by various others factors.


In Navstar GPS system there are 24 satellites and all GPS satellite transmits data (signal) which move with speed of light (approximate 300,000KM/sec) that indicates its location and the current time.


All GPS satellites synchronize operations so that these repeating signals are transmitted at the same instant. These signals arrive at a GPS receiver at slightly different times because some satellites are slightly away from one another (Can see in above pic). The receiver calculates its position in three dimensions when the receiver estimates the distance (using basic equation Distance = Speed*Time) of at least four GPS satellites.


The accuracy level of GPS (most consumer GPS units) is between +/-5 to 15 meter and this accuracy level is affected by various other factors. But one factor which highly affect the accuracy level is called “Signal Multipath” (This is due to reflection of signal to large building, larger rock surface, terrain, electronic interference, or sometimes even dense foliage before it reaches to receiver, that’s lead to increases the travel time of the signal and thereby causing errors).

The developing countries like India which is in nascent stage of its development, there is no changes that we can control large buildings, electronic interface etc. so, in coming years we are going to suffer address and location problem due to the inaccuracy of GPS.

The accuracy level of GPS can increase significantly through using “Differential Global Positioning System” (DGPS). There are various DGPS available for individuals but if we want to improve GPS accuracy there need centralized DGPS system.

PS: This article was initially posted on my LinkedIn Plus (14/03/2017)

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