GPS used to be the Global Positioning System. Meaning, the only system of its kind. Although free to use across the world, the system is operated and controlled by the US government. Naturally, this makes other countries uneasy. During the 2008 war in South Ossetia, when the US backed Georgia and Russia backed South Ossetian separatists, GPS was blacked out in the region. There are several projects underway to make global navigation satellite systems independent of GPS. Russia is the furthest underway, with its GLONASS system, which was originally up and running in the nineties, but fell into disrepair. This October, they’ve finally restored global coverage to the system. China is also trying to build its own GPS, which it calls the Compass navigation system. And the European Union is building Galileo, which will be more advanced than GPS when it becomes operational sometime between 2015 and 2020. Finally, India is building its own, regional satellite navigation system.
The principles behind satellite navigation remain the same. A constellation of satellites orbit Earth, spaced apart so that at least four remain above the horizon everywhere and at all times. Using time and orbital information from these satellites, a ground receiver can calculate its position.
dailymeh posted this on October 10, 2011
