In the beginning
the system was only intended for military use, but that changed in 1983 when a
Soviet interceptor plane shot down a civilian aircraft in restricted Soviet
space killing all on board, after the craft had mistakenly wandered off course.
This was something that GPS could have prevented, and so President Reagan soon
announced that GPS would be available for all once it was complete.
GPS is a
satellite-controlled navigation system that is used by the military and general
public alike. For the general public it is a useful tool, a step forward from
the one dimensional and none interactive maps that some people find difficult
to read and follow. There are many different brands of GPS receivers, and they
each offer different features, some of which may not even be related to GPS.
Prices for GPS
devices start at around $100 for a basic device that is monochrome and hand
held, and increase to more than $2000 for a larger, colour device with a
greater number of features. At its most basic however, GPS is not a standalone,
or navigation aid.
The lower-level
devices would be a hand-held GPS navigation tool, such that might include
preloaded maps of the country of purchase, be waterproof and have a backlit LCD
screen. Or for similar pricing a basic GPS device with colour screen, voice
guidance to tell you when to take what turns and onto what streets, the power
to add new maps, and may have a choice of languages and choice of the voice
that the GPS uses.
At around $200 you
add in features such as a touch screen to your GPS device for inputting
addresses and accessing menus as well as blue tooth capability. Another step up
and you see features such as AAA tour books added in and automatic redirect;
and important feature for a GPS navigator because you can never be sure when
you will miss a turn and need to get back on track via an alternative route.
At the top end, GPS
devices include such things as voice recognition, allowing you to speak your
start and end points, and any points of interest in best. They might also
include non-GPS features like DVD players, iPod docks and even give you traffic
updates.
Though many people
do not realise it, GPS receivers have been present for some time in many cell
phones, and allow the phone to be traced precisely, when the police request
such information. In this way GPS has been used to help find missing people,
and attempts have been made to use it to help the victims of kidnapping.
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