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'''Global Positioning System''' ('''GPS''') is a [[United States]] [[satellite]] system that lets those on the ground, on the water or in the air determine their position with extreme accuracy based on timing signals sent from satellites.

'''Global Positioning System''' ('''GPS''') is a [[United States]] [[satellite]] system that lets those on the ground, on the water or in the air determine their position with extreme accuracy based on timing signals sent from satellites. You triangulate your position through the use of a GPS receiver.

The system was developed by the US [[Department of Defense]] and made available to the general public in 1983 under orders of [[Ronald Reagan | President Reagan]]. GPS for civilian use used to include a mechanism called Selective Availability that intentionally limited the accuracy of GPS, a mechanism originally intended to confuse potential enemies who might launch a missile attack, but Selective Availability was disabled in 2000, and appears unlikely to be reinstated in the foreseeable future.

The system was developed by the US [[Department of Defense]] and made available to the general public in 1983 under orders of [[Ronald Reagan | President Reagan]]. GPS for civilian use used to include a mechanism called Selective Availability that intentionally limited the accuracy of GPS, a mechanism originally intended to confuse potential enemies who might launch a missile attack, but Selective Availability was disabled in 2000, and appears unlikely to be reinstated in the foreseeable future.

Until 1985, the eleven ''Block I'' satellites were built. This number was increased until 1989 by the ''Block II'' satellites. GPS today uses 24 satellites and numerous ground stations.

Until 1985, the eleven ''Block I'' satellites were built. This number was increased until 1989 by the ''Block II'' satellites. GPS today uses 24 satellites and numerous ground stations.

==External Links==

 

*[http://code8100.nrl.navy.mil/about/heritage/nts.htm Timation], U.S. Naval Research Laboratory, Space Systems Development Department (SSDD)

==GPS Receivers==

*[http://pnt.gov/101/gps.html The Global Positioning System], Space-Based Positioning Navigation & Timing, National Executive Comittee

GPS receivers are an extremely fast and easy way to navigate. With the ability to tell you where you are, where you're heading, how to get there, and where just about anything else is they are tough to beat for convenience. It is easy to come to rely on GPS with all of its features and convenience, but it is important to remember that like any other electronic device it may fail. While the GPS network itself it very robust, requiring little more than regular corrections from ground based stations, GPS receivers are small relatively fragile devices than may break or run out of power.

*[http://mms.nps.gov/gis/gps/How_GPS_Works.ppt An Introduction to the Global Positioning System], Charlie Leonard, 1999 (revised 2001, 2002), PowerPointPresentation

 

That is why [[maps]] and [[compass]] are two of the two most essential pieces of navigation gear that one should carry. GPS devices and [[cell phone]]s with [[Google]] maps may breakdown or run out of [[battery|batteries]] during an [[emergency]], [[disaster]] or a [[Post Apocalyptic World]] - [[SHTF]] - [[TEOTWAWKI]] event. Also the sun isn't always shining, and it takes a great deal of time and effort to learn to stellar navigation, however a map and compass will continue to work until your break or lose them.

 

* [[GPS]], [[Map]] and [[Compass]] for [[Navigation]]

* [[Bug-out bag]]

 

* {{cite book|url=http://books.google.com/?id=lvI1a5J_4ewC|title=The global positioning system|author=Parkinson; Spilker|publisher=American Institute of Aeronautics and Astronautics|isbn=978-1-56347-106-3|year=1996}}

* {{cite book|url=http://books.google.com/?id=t1lBTH42mOcC&printsec=frontcover&dq=GPS+and+GALILEO#v=onepage&q&f=false|title=GPS and Galileo|author=Jaizki Mendizabal; Roc Berenguer; Juan Melendez|publisher=McGraw Hill|isbn=978-0-07-159869-9|year=2009}}

* {{cite book|title=[[s:The American Practical Navigator|The American Practical Navigator – Chapter 11 ''Satellite Navigation'']]|author=Nathaniel Bowditch|publisher=United States government|year=2002}}

* [http://ocw.mit.edu/courses/earth-atmospheric-and-planetary-sciences/12-540-principles-of-the-global-positioning-system-spring-2012/ Global Positioning System] Open Courseware from [[MIT]], 2012

==References==

==References==

[[Category:Telecommunications]]

[[Category:Telecommunications]]

[[Category:Geography]]

[[Category:Geography]]