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GPS stands for
Global Positioning System. GPS becomes an integral component of the
emerging Global Information Infrastructure, with applications
spreading from mapping and surveying to international air traffic
management and global change research. GPS is a technology that is
ideally suited to navigation and positioning.
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GPS made up of a
network of 24 satellites placed into orbit by the U.S. Department of
Defense, USA. The basic GPS is defined as the constellation of
satellites, the navigation payloads which produce the GPS signals,
ground stations, data links, and associated command and control
facilities.
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GPS works in any
weather conditions, anywhere in the world, 24 hours a day with no
additional cost or prior registration
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Four
GPS satellite signals are used to compute positions in three
dimensions and the time offset in the receiver clock
GPS consists of 3 segments: space, control, and user.
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The Space
Segment,
consists of a minimum of 24 operational satellites in six circular
orbits 20,200 km (10,900 NM) above the earth with a 12 hour period.
The satellites are spaced in orbit so that at any time a minimum of
6 satellites will be in view to users anywhere in the world. The
satellites continuously broadcast position and time data to users
throughout the world.
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The Control
Segment
consists of a master control station in Colorado Springs, USA The
monitor stations track all GPS satellites in view and collect
ranging information from the satellite broadcasts. The monitor
stations send the information collected from each of the satellites
back to the master control station, which computes precise satellite
orbits. The information is then formatted into updated navigation
messages for each satellite. The updated information is transmitted
to each satellite via the ground antennas, which also transmit and
receive satellite control and monitoring signals.
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The User Segment
consists of the receivers, processors, and antennas that allow land,
sea, or airborne operators to receive the GPS satellite broadcasts
and compute their precise position, velocity and time.
The
GPS concept of operation is based upon satellite ranging. Users figure
their position on the earth by measuring their distance from the group
of satellites in space. The satellites act as precise reference points.
Each
GPS satellite transmits an accurate position and time signal. The user's
receiver measures the time delay for the signal to reach the receiver,
which is the direct measure of the apparent range to the satellite.
Measurements collected simultaneously from four satellites are processed
to solve for the three dimensions of position, velocity and time.
GPS receivers collect signals from satellites in view. They display the
user's position, velocity, and time, as needed for their marine,
terrestrial, or aeronautical applications. Some display additional data,
such as distance and bearing to selected waypoints or digital charts. |
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Global5 Co., Ltd.
2013A
ชั้น 2
โซนโรบินสัน
ซีคอนแสควร์ กรุงเทพ
Tel: 02-721-9811, 02-748-2566, 086-612-5252, 083-685-1200,
086-881-1154
www.global5thailand.com |
