external image gps.jpg


GPS (Global Positioning Systems), are international navigational systems where satellites orbiting the earth in space are used to determine absolute locations of any location on earth. There are 24 satellites and each has a corresponding ground station. It was originally intended for military use but in the 1980's the U.S government made it available for civilian use.


How it works


GPS satellites orbit the earth twice every 24 hours transmitting signal information to ground stations. GPS receivers take this signals and use triangulation to calculate a user's exact location.

GPS from Space


The Space Segment of the system consists of the GPS satellites. These space vehicles (SVs) send radio signals from space. The nominal GPS Operational Constellation consists of 24 satellites that orbit the earth in 12 hours. There are often more than 24 operational satellites as new ones are launched to replace older satellites. The satellite orbits repeat almost the same ground track (as the earth turns beneath them) once each day. The orbit altitude is such that the satellites repeat the same track and configuration over any point approximately each 24 hours (4 minutes earlier each day). There are six orbital planes (with nominally four SVs in each), equally spaced (60 degrees apart), and inclined at about fifty-five degrees with respect to the equatorial plane. This constellation provides the user with between five and eight SVs visible from any point on the earth.

GPS in use


Navigation: People use a navigation aid in their cars, ships, airplane, or even be positioned in an official location. In fact, a GPS system can be carried by individuals who are hiking instead of a compass. GPS is also used by the visually impaired such as NOPPA, BrailleNote GPS.

In Canada and the British Isles, Datalink’s Sentry system allows officers to summon help while away from a phone or police vehicle. Upon an emergency, an officer presses a panic button on a small pager like device carried on their belt. This panic button releases a signal to the GPS tracking system inside their police vehicle. The GPS tracking system then notifies the police dispatcher with their current location.

Police officers also utilize GPS systems as a form of surveillance. According to ATX Technologies, manufacturers in vehicle GPS monitoring systems, ‘bait cars’ have successfully decreased car theft by 60% in a little over one month. For policemen, GPS systems have helped recover many stolen cars, equipment and merchandise.

GPS format


GPS can be in almost any format. Now days, it can be integrated into cars, cellphones, or even ipods.

GPS Hardware


GPS-iPAQ.jpg
Handheld GPS

casio_gps.gif
Wristwatch GPS

sony_3d-gps_tokyo.jpg
In-Car GPS

External Links


*
ATX Group (2006). Retrieved on February 24. 2006 from: http://www.track.com/content/telHome.php
  • Image courtesy of:
Google Images. GPS. Online at: <http://www.dtic.mil/jointvision/graphics/gps.jpg>

Google Images. GPS. Online at: <http://www.pocketpcmag.com/_archives/Mar01/images/GPS-iPAQ.jpg>

Google Images. GPS. Online at: <http://www.bullnet.co.uk/shops/test/images/casio_gps.gif>

Google Images. Car GPS. Online at: http://www.coolhunting.com/sony_3d-gps_tokyo.jpg


See also


Telematics