Global Positioning System
From ArticleWorld
The Global Positioning System is often referred to as GPS and is the only fully operational Satellite Navigation System. Although there are many civilian applications for the Global Positioning System, it is actually owned and operated by the US Department of Defense. The estimated cost of maintaining the system is US$400 million per year, but it can be used by anyone, free of charge. The GPS system is managed and maintained by the 2nd Space Operations Squadron based at Schriever Air Force Base. Other satellite navigation systems are under development, including the Russian GLONASS, and the European Galileo.
Overview
The main application of a Satellite Navigation System is for determining your exact location anywhere on the Earth or in Earth orbit by utilizing a highly accurate time reference. The Global Positioning System signal is accurate to about 5 meters (16 ft), and this is able to be improved by error-correcting techniques to about 1 cm (.4 in) over short distances.
The Global Positioning System has three main components:
- Space – over 24 GPS are satellites in orbit
- Control – ground stations located around the globe for monitoring, synchronizing, and collecting data from the satellites
- User – this encompasses the receivers that decode the transmissions and calculate the position
The first GPS satellite was launched in February 1978, and older satellites are regularly replaced by newer ones.
Military applications
The Global Positioning System is referred to as the NAVSTAR GPS - Navigation Signal Timing and Ranging Global Positioning System) by the US military. The main military uses of the GPS are:
- Enhanced command and control of military forces through enhanced location awareness
- Assisting accurate targeting of smart bombs, cruise missiles, or other weapons
- Carriage of nuclear detonation detectors as part of the United States Nuclear Detonation Detection System
Civilian applications
There are a number of civilian applications for the GPS system. These include:
- Civilian navigation – low cost GPS receivers are widely available to enable users to utilize the system as a navigational aid
- Precise Time Reference - numerous synchronization systems use GPS as their accurate time source
- GPS for the visually impaired – this involves integrating GPS into one of the many navigation-assistance systems for the blind
- Geocaching - a recreational pursuit where a GPS unit is used to search for objects purposely concealed
- GPS tracking - automatically follows and records a vehicle's, person's, or pet's movements