The Global Positioning System is currently the only fully-functional satellite navigation system. Developed by the United States Department of Defense, the first experimental satellite was launched in 1978. It is officially named NAVSTAR GPS (Navigation Satellite Timing and Ranging Global Positioning System)
GPS is an indispensable tool for navigation, map-making and land surveying around the world. Here are few of its major applications:

Automobiles and aircraft, equipped with GPS receivers, display moving maps and information about location, speed, direction, and nearby streets and landmarks. Boats and ships use GPS too. Maritime GPS units include functions useful on water, such as “man overboard” (MOB) functions — thus simplifying the rescue efforts.

Mining and precision agriculture use GPS to automatically guide equipment to various locations and provide visual aids for their operators.

Bikers, hikers and climbers use GPS in racing, touring and locating positions (which also aid
in rescue operations).

Surveying, mapping and GIS, and in geophysics and geology, the application of GPS is obvious.

Used for precise time reference. A range of systems, including seismology sensors, are
synchronised with it so that events may be timed accurately.

Used for mobile satellite communications. On a moving ship or train, for example.

For emergency and location-based services. For example, it may find a phone's geographic location and aid a rescue mission.

How it works

GPS satellites transmit signals that allow a GPS receiver to determine its location, speed
and direction. It calculates its position by measuring the distance between itself and
three or more GPS satellites. The time between the transmission and reception of each
GPS radio signal gives the distance to each satellite, because the signal travels at a known speed. The signals also carry information about the satellites' location. By
determining the position of, and distance to, at least three satellites, the receiver can
compute its position using Trilateration (use of the geometry of triangles and the known
locations of reference points, and the measured distance between the subject and eachreference point to calculate the location of the subject).

Mapping at your finger tips

The precious art and science of map making was until very recently available only to those with wealth and power. Now it has undergone a revolutionary change. The evolution of the Internet and consumer electronics have opened up numerous possibilities of digital story telling. Here are some resources that would put the power of making maps in your hands.

Become a ‘neogeographer’

Children, marginalised by a global economy and educated by schools and the media to
become rootless members of a commercial monoculture, will be ill-prepared to construct
institutions capable of equitably providing for human needs in ways that do not
compromise the long-term health of natural systems. The creation of an ecologically
sustainable society will require people who share a deep commitment to the social and
natural milieus in which they live as well as a knowledge base that is sensitve to the
dynamics and needs of these environments.

Greg Smith,Educator
—"Rooting Children in Place,"Encounter:Education for
Meaning and Social Justice,1998

OpenStreetMap
OpenStreetMap is a free editable map of the whole world. It is made by people like you. OpenStreetMap allows you to view, edit and use geographical data in a collaborative way from anywhere on Earth.
The project was started because most maps you think of as free actually have legal or technical restrictions on their use, holding back people from using them in creative,
productive or unexpected ways.
www.openstreetmap.com

networked mapping platform which makes it easy to find, create, share - The People's Atlas.
www.platial.com

GIS for free
Quantum GIS (QGIS) is a user friendly Open Source
Geographic Information System (GIS) that runs on Linux, Unix, Mac OSX, and Windows.
http://qgis.org/

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