GPS

Global Positioning System (GPS) is a satellite navigation system. It provides real-time location and time based information based on data from GPS satellites positioned at various points around the Earth.

Developed in 1973, by the US Government all you need to access GPS is a GPS Receiver. Credit for its invention goes to Roger L. Easton.

GPS is based on the principle of triangulation which is basically the process of determining the location of point by measuring the angles made to it by three known points. GPS triangulates off satellites to pin-point your exact location. 3 satellites are required to provide latitude and longitude data, and a fourth for altitude. There are 24 GPS satellites currently each with its own atomic clock on board. Moving at the speed of light the satellites synchronize data so that their signals are transmitted at the same instant.

The satellites are maintained by the United States Air Force, and orbit with a period of 12 hours. The GPS receiver is aware of the position of the satellites by the transmissions they give out.

The accuracy of GPS is estimated to be within a 10-20 meter range for handheld devices. Other devices use a method called differential GPS and have a much higher accuracy rate.

Not only does GPS store your current location, but you’re past locations as well. So in addition to knowing where you are now, you can also know where you’ve been this morning, or all week for that matter. This is why, I suppose, it is commonly referred to as the ultimate stalking tool.