The Global Positioning System uses radio signals from artificial satellites to triangulate an object's location. Today this technology is being used in an expanding range of fields. Originally developed in the United States for military use, GPS has spawned a variety of commercial products, including car-navigation systems and personal locator units. There are even rice-planting machines with built-in GPS receivers. Before long, GPS will also be widely used in new civilian air traffic control systems and such large-scale engineering projects as land reclamations.

Devices for Personal Use
GPS consists of an array of 24 satellites orbiting 24,000 kilometers (14,900 miles) above the Earth. GPS units use radio signals from any three of these satellites to calculate longitude and latitude. The system was developed by the U.S. military in the early 1970s for applications that include air and naval navigation control, missile guidance, and the positioning of tanks and troops. The United States also made GPS available for civilian use, albeit with reduced accuracy.

The first civilian application of GPS was the car-navigation systems that first appeared in the early 1990s. These systems receive signals from GPS satellites to determine a vehicle's location, then show it on a display map. They can also guide the driver to a destination using arrows or spoken directions. In addition to route guidance, the latest models also provide information about traffic conditions, including accidents, congestion, and road works, as well as on the availability of parking space. With top-of-the-line systems users can even make restaurant reservations, access the Internet, and process e-mail. Their use is spreading rapidly: From just 30,000 systems in 1992, annual sales soared to more than a million in 1997.

The concept of car navigation has been extended to portable units. Among the recently launched models are systems built into cell phones and even wristwatches. Units designed for climbers and anglers come preprogrammed with 6,000 locations that include major mountain peaks and lakes throughout Japan. In addition to determining their current position and rate of movement, users can also input specific locations, such as good fishing spots. Models designed for city use provide detailed maps, and many have additional features, such as digital cameras, Web browsers, and personal organizers. Another new system, scheduled for release in December 1999, will combine GPS and cell phone technology in a unit that can be used to track the position of another person--such as a child or elderly person prone to wandering off--even the whereabouts of a roaming pet.

A uniquely Japanese product is the GPS-equipped rice-planting machine. The machine uses GPS data to keep track of its location and to plant rice seedlings at exact intervals. When it reaches the edge of the field, it automatically turns around and goes on to plant the next row.

Large-Scale Traffic Control
GPS is used extensively in major engineering projects. One such project is the second phase of construction at the Kansai International Airport, off the southern coast of Osaka Prefecture. Work will start in the near future, and the new facilities are expected to open in 2007. The project calls for the construction of a 4,000-meter (4,400-yard) runway on newly reclaimed land adjacent to the present airport with an area of 542 hectares. At the peak of the project, some 200 machinery units will be involved in the works. To ensure safe and smooth operations, traffic control will be carried out using GPS units installed in all units.

GPS technology will also be used in a new air traffic control system that is being developed to ease congestion in the increasingly crowded air lanes of the northern Pacific. At present, aircraft flying over oceans are unable to receive signals from land-based radar stations, and the inertial navigation systems used to determine aircraft positions are prone to substantial errors. With the new system, data will be exchanged between aircraft and air traffic controllers via a geostationary satellite 36,000 kilometers (22,400 miles) above the Earth, and aircraft positions will be accurately monitored using GPS equipment. The Ministry of Transport will launch the first of two satellites (the second will stand by in orbit in case the first breaks down) in September 1999. The new system, which will come on line in April 2000, will allow a reduction of two-thirds in the interval between flights, bringing a dramatic increase in the number of flights.

The United States has indicated that it will improve the accuracy of the civilian positioning service. This is expected to add further impetus to civilian use of GPS technology both in Japan and abroad.

Edited by Japan Echo Inc. based on domestic Japanese news sources. Articles presented here are offered for reference purposes and do not necessarily represent the policy or views of the Japanese Government.

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