Thursday, October 15, 2009 | Posted by kamlesh kawadkar

See your location , get a turn-by-turn direction guide through the confusing streets or even check for the live traffic information directly on your mobile via GPS, Wi-Fi , or even cellular towers & a proper navigation software. Nowadays smartphone come along with inbuilt GPS capabilities & professional navigation software,else one can have an external GPS reciever plus third party application like Google Maps.

The navigation app works by utilizing the GPS location of the mobile device, if it is available. this information is supplemented by the software determining the nearest cell sites. The software then plots the streets that are available in the estimated range of the cell site based on the transmitters rated power.

Like a cell phone, a GPS receiver relies on radio waves. But instead of using towers on the ground, it communicates with satellites that orbit the Earth. There are currently 27 GPS satellites in orbit of which 24 are in active use & 3 act as a backup in case anothert satellite fails. In order to determine your location, a GPS reciever has to determine the locations of atleast three satellites above you & where you are in relation to those satellites. The reciever then uses trilateration to determine your exact location. Basically, it draws a sphere around each of three satellites it can locate. These three spheres intersect in 2 points: one is in space & one is on the ground. The point on the ground at which the three spheres intersects is your location. A GPS receiver has to have a clear line of sight to the satellite to operate, so dense tree cover & buildings can keep it from getting a fix on your location.