Page 592 - Ultimate Visual Dictionary (DK)

THE MODERN WORLD
Global positioning

system

Cigarette
THE GLOBAL POSITIONING SYSTEM (GPS) is a network of lighter
24 navigation satellites orbiting the Earth that people can adapter and
speaker cable
use to pinpoint their position. The satellites orbit at a height
of 12,500 miles (20,000 km). A GPS receiver picks up signals
Antenna
from any of these satellites that are above the horizon. It uses
information in each signal to work out how far away it is from
the satellite. It can calculate its position on the Earth’s surface
when it has information from at least three satellites. A basic
GPS receiver shows the latitude and longitude Page key
of its position on its screen. More advanced IN-CAR GPS
On/off and screen
receivers, especially those designed for use
control button
in vehicles, show their position on a digital
map. These receivers often show extra Enter key
information, such as the vehicle’s speed and
Quit key
the length of the journey. Some receivers
warn drivers if they exceed the speed limit Rocker pad
for a road and even tell drivers which
traffic lane to use at the next junction. Menu key
Directions are shown on the screen and
Speak key
also spoken by a synthesized voice.
Liquid crystal display
HOW GPS WORKS (LCD) screen Find key
Zoom keys Route key
Satellite 2
Satellite 1 The receiver takes
a reading of its
IN-CAR MOUNTING
distance from two MOUNTING BRACKET
satellites. The BRACKET ASSEMBLY
receiver is located
along the plane
where the two
resultant spheres QUICK-RELEASE BASE
meet
Earth

Satellite 3
A signal from a third
satellite defines two
positions on that plane.
The position on the
Earth’s surface is read
as the correct location

Locking lever

Ratcheted
Release catch base

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