GPS, or Global Positioning System has been operational since December 1993, but its history lies much further back to the 1940s when ground based navigation systems such as Decca Navigator began. This, while it planted the seed of inspiration would not take another step forward until the 1957 launch of the first Sputnik by the Soviet union showed that satellites were a possibility. 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 it's most basic however, GPS is not a stand alone, 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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