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A GPS navigation device is a device that accurately calculates geographical location by receiving information from GPS satellites. Initially it was used by the United States military, but now most receivers are in automobiles and smartphones. The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of a minimum of 24, but currently 30, satellites placed into orbit by the U.S. Department of Defense. Military action was the original intent for GPS, but in the 1980s, the U.S. government decided to allow the GPS program to be used by civilians. The satellite data is free and works anywhere in the world. GPS devices may have capabilities such as: * maps, including streets maps, displayed in human readable format via text or in a graphical format, * turn-by-turn navigation directions to a human in charge of a vehicle or vessel via text or speech, * directions fed directly to an autonomous vehicle such as a robotic probe, * traffic congestion maps (depicting either historical or real time data) and suggested alternative directions, * information on nearby amenities such as restaurants, fueling stations, and tourist attractions. GPS devices may be able to indicate: * the roads or paths available, * traffic congestion and alternative routes, * roads or paths that might be taken to get to the destination, * if some roads are busy (now or historically) the best route to take, * The location of food, banks, hotels, fuel, airports or other places of interests, * the shortest route between the two locations, * the different options to drive on highway or back roads. == History == (詳細はCold War of the latter 20th century. The multibillion dollar expense of this program was initially justified by military interest. In 1960, the US Navy put into service its Transit satellite based navigation system to aid in ship navigation. From 1960 - 1982, as the benefits were proven over time, the US military consistently improved and refined its satellite navigation technology and satellite system. In 1973, the US military began to plan for a comprehensive worldwide navigational system which eventually became known as the GPS (global positioning satellite) system. In 1983, in the wake of the tragedy of the downing of the Korean Airlines Flight 007, an aircraft which was shot down while in Soviet airspace due to a navigational error, president Reagan announced that the navigation capabilities of the existing military-GPS system were to be made available for dual civilian use, however, civilians were to initially only be given access to the slightly degraded "Selective Availability" positioning signal. This new availability of the US military GPS system for civilian use required a certain technical collaboration with the private sector for some time, before it could become a commercial reality. In 1989, Magellan Navigation Inc. unveiled its Magellan NAV 1000—the world’s first commercial handheld GPS receiver. These units initially sold for approximately $2,900 each. In 2000, the Clinton administration ordered the removal of military use signal restrictions, thus providing full commercial access to the use of the US GPS satellite system. As GPS navigation systems became more and more widespread and popular, the pricing of such systems began to fall, and their widespread availability steadily increased. Also, several additional manufacturers of these systems, such as Garmin (1991), Benefon (1999), and TomTom (2002) entered the market. Benefon's 1999 entry into the market also presented users with the world's first phone based GPS navigation system. Later, as the smart phone industry developed, a GPS chip eventually became standard equipment for most smart phone manufacturers. To date, ever more popular GPS navigation systems and devices continue to proliferate with newly developed software and hardware applications. While the American GPS was the first satellite navigation system to be deployed on a fully global scale, and to be made available for commercial use, this is not the only system of its type. Due to military and other concerns, similar global or regional systems have been, or will soon be deployed by Russia, the European Union, China, India, and Japan. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「GPS navigation device」の詳細全文を読む スポンサード リンク
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