NaviGadget

GPS Becomes Ubiquitous

May 8, 2006 gps navigation

A nice read from physorg.com about GPS technology. Nothing new but informative.

GPS is everywhere these days. Once the jealously guarded domain of the military, it now helps even granny find her way to market.

GPS is essentially an improvement over previous radio based navigation systems. British WWII bombers first used a system called GEE. This consisted of radio “beams” which guided them to bombing points. In the 1960s the Navy used TRANSIT and in the 1970s, boaters used a system called LORAN. Basically, a radio receiver calculated the distance to two or more radio transmitters and computed its relative position using 2D coordinates. All that changed in 1993 when the last of the NAVSTAR GPS – Navigation Signal Timing and Ranging Global Positioning System – satellites were put into orbit.

GPS’s big advantage over older systems is its ability to give 3D coordinates – latitude, longitude and elevation, great for flyers, hikers and climbers. Another is its accuracy – to within a centimeter in some models.

The basis for this technology is the atomic clock. With the ability to synchronize their time to billionth of a second on each satellite, the systems know their exact position in time and space. They also keep an internal log of the exact positions of other satellites to aid receivers in location fixing…