 What
is GPS and how is it used?
GPS stands for the Global Positioning System. GPS is a navigational
system that can accurately locate your position anywhere on the Earth. The
U.S. Department of Defense started development of the $12 billion GPS satellite
navigation system in the 1970s to provide continuous, worldwide positioning
and navigation data to U.S. military forces worldwide. Now GPS technology
is available to everyone, everywhere, day and night, and at no cost for use
of the navigational data. GPS uses over 20 satellites which are located 11,000
miles above the Earth. The satellites transmit data back to Earth and by locking
onto this transmitted data, a GPS receiver can process this data to triangulate
its precise location on earth.
GPS operates in all weather conditions, 24 hours a day. GPS is used
worldwide for precise navigation on water, land, and air. Some of
the many applications it can be used in are: auto navigation, boating, fishing,
golfing,
hunting, scouting, hiking, camping, biking, rafting, hot air ballooning,
aviation, snowmobiling, skiing, search and rescue, 4 wheeling, vehicle tracking,
and
many more.
How does GPS determine my position?
Every point on Earth has a specific address or coordinates, using
a horizontal line (latitude) which crosses a vertical line (longitude). GPS
receivers record and report your current position with latitude/longitude
coordinates, in addition to other important navigation information like heading,
bearing, distance-to-go, time-to-go, and much more.
Using atomic clocks (accurate to within one second every 70,000 years)
and location data, each satellite continuously broadcasts the time and its
position. A GPS receiver uses signals from three or more satellites at once
to determine the user's position on earth. By measuring the elapsed
time between the transmission and the reception of a satellite signal, the
GPS receiver calculates the distance between the user and each satellite.
Using the distance measurements of at least three satellites in an algorithm
computation, the GPS receiver arrives at an accurate position fix. Information
must be received from three satellites in order to obtain two-dimensional
(latitude and longitude) fixes, and four satellites are required for three-dimensional
(latitude, longitude and altitude) positioning. The position information in
a GPS receiver may be displayed as longitude/latitude, Universal Transverse
Mercator, Military Grid or other system coordinates.
How accurate is GPS?
There were previously two levels of GPS services, one for civilian
access and the second encrypted for exclusive military use. The civilian GPS
signals were subjected to Selective Availability (SA) interference by the
US Government, which meant the civilian GPS signal accuracy was reduced to
100 meters. However, on May 1, 2000, the U.S. government removed SA from GPS
signals, which resulted in ten times greater accuracy for public users of
GPS — position fixes that are usually within 10 meters.
What GPS applications are there?
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Navigation for your car |
|
Marine Navigation |
|
Golfing |
|
PDA navigation |
|
Fleet Tracking |
|
Kid locator |
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Satellite TV
