Explain..The Global positioning system.. please ..very urgent
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The GPS (Global Positioning System) is a "constellation" of approximately 30 well-spaced satellites that orbit the Earth and make it possible for people with ground receivers to pinpoint their geographic location. The location accuracy is anywhere from 100 to 10 meters for most equipment
The Global Positioning System (GPS), originally Navstar GPS,[1] is a satellite-based radionavigationsystem owned by the United States government and operated by the United States Air Force.[2] It is a global navigation satellite system that provides geolocation and time information to a GPS receiveranywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.[3] Obstacles such as mountains and buildings block the relatively weak GPS signals.
Global Positioning System (GPS)
Country/ies of originUnited StatesOperator(s)AFSPCTypeMilitary, civilianStatusOperationalCoverageGlobalAccuracy500–30 cm (20–1 ft)Constellation sizeTotal satellites33Satellites in orbit31First launchFebruary 1978; 41 years agoTotal launches72Orbital characteristicsRegime(s)6x MEO planesOrbital height20,180 km (12,540 mi)
Artist's conception of GPS Block II-F satellite in Earth orbit.
Civilian GPS receivers ("GPS navigation device") in a marine application.
Automotive navigation systemin a taxicab.
A U.S. Air Force Senior Airmanruns through a checklist during Global Positioning System satellite operations.
The GPS does not require the user to transmit any data, and it operates independently of any telephonic or internet reception, though these technologies can enhance the usefulness of the GPS positioning information. The GPS provides critical positioning capabilities to military, civil, and commercial users around the world. The United States government created the system, maintains it, and makes it freely accessible to anyone with a GPS receiver.[4]
The GPS project was launched by the U.S. Department of Defense in 1973 for use by the United States military and became fully operational in 1995. It was allowed for civilian use in the 1980s. Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS and implement the next generation of GPS Block IIIAsatellites and Next Generation Operational Control System (OCX).[5] Announcements from Vice President Al Gore and the White House in 1998 initiated these changes. In 2000, the U.S. Congressauthorized the modernization effort, GPS III. During the 1990s, GPS quality was degraded by the United States government in a program called "Selective Availability"; this was discontinued in May 2000 by a law signed by President Bill Clinton.[6]
The GPS system is provided by the United States government, which can selectively deny access to the system, as happened to the Indian military in 1999 during the Kargil War, or degrade the service at any time.[7] As a result, several countries have developed or are in the process of setting up other global or regional satellite navigation systems. The Russian Global Navigation Satellite System (GLONASS) was developed contemporaneously with GPS, but suffered from incomplete coverage of the globe until the mid-2000s.[8] GLONASS can be added to GPS devices, making more satellites available and enabling positions to be fixed more quickly and accurately, to within two meters (6.6 ft).[9] China's BeiDou Navigation Satellite System is due to achieve global reach in 2020. There are also the European Union Galileo positioning system, and India's NAVIC. Japan's Quasi-Zenith Satellite System (QZSS) is a GPS satellite-based augmentation system to enhance GPS's accuracy.
When selective availability was lifted in 2000, GPS had about a five-meter (16 ft) accuracy. The latest stage of accuracy enhancement uses the L5 band and is now fully deployed. GPS receivers released in 2018 that use the L5 band can have much higher accuracy, pinpointing to within 30 centimetres or 11.8 inches.[10][11]