29 Facts About GPS


Global Positioning System, originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force.

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GPS project was started by the U S Department of Defense in 1973.

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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 IIIA satellites and Next Generation Operational Control System .

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Russian Global Navigation Satellite System was developed contemporaneously with GPS, but suffered from incomplete coverage of the globe until the mid-2000s.

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GPS project was launched in the United States in 1973 to overcome the limitations of previous navigation systems, combining ideas from several predecessors, including classified engineering design studies from the 1960s.

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Design of GPS is based partly on similar ground-based radio-navigation systems, such as LORAN and the Decca Navigator, developed in the early 1940s.

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The design of GPS corrects for this difference; because without doing so, GPS calculated positions would accumulate errors of up to 10 kilometers per day .

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GPS's was concerned with the curving of the paths of radio waves traversing the ionosphere from NavSTAR satellites.

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Since its deployment, the U S has implemented several improvements to the GPS service, including new signals for civil use and increased accuracy and integrity for all users, all the while maintaining compatibility with existing GPS equipment.

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GPS is owned and operated by the United States government as a national resource.

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In 1998, GPS technology was inducted into the Space Foundation Space Technology Hall of Fame.

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GPS receiver calculates its own four-dimensional position in spacetime based on data received from multiple GPS satellites.

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GPS receivers have clocks as well, but they are less stable and less precise.

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In practice the receiver position and the offset of the receiver clock relative to the GPS time are computed simultaneously, using the navigation equations to process the TOFs.

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GPS requires four or more satellites to be visible for accurate navigation.

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User segment is composed of hundreds of thousands of U S and allied military users of the secure GPS Precise Positioning Service, and tens of millions of civil, commercial and scientific users of the Standard Positioning Service.

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In general, GPS receivers are composed of an antenna, tuned to the frequencies transmitted by the satellites, receiver-processors, and a highly stable clock .

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GPS has become a widely deployed and useful tool for commerce, scientific uses, tracking, and surveillance.

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The war demonstrated the vulnerability of GPS to being jammed, when Iraqi forces installed jamming devices on likely targets that emitted radio noise, disrupting reception of the weak GPS signal.

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GPS's vulnerability to jamming is a threat that continues to grow as jamming equipment and experience grows.

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GPS signals have been reported to have been jammed many times over the years for military purposes.

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The difference is that GPS time is not corrected to match the rotation of the Earth, so it does not contain leap seconds or other corrections that are periodically added to UTC.

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GPS time was set to match UTC in 1980, but has since diverged.

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The lack of corrections means that GPS time remains at a constant offset with International Atomic Time .

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GPS time is theoretically accurate to about 14 nanoseconds, due to the clock drift relative to International Atomic Time that the atomic clocks in GPS transmitters experience Most receivers lose some accuracy in their interpretation of the signals and are only accurate to about 100 nanoseconds.

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Navigational signals transmitted by GPS satellites encode a variety of information including satellite positions, the state of the internal clocks, and the health of the network.

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The GPS community had not objected to the LightSquared applications until November 2010, when LightSquared applied for a modification to its Ancillary Terrestrial Component authorization.

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GPS was initially developed assuming use of a numerical least-squares solution method—i.

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GPS makes corrections for receiver clock errors and other effects, but some residual errors remain uncorrected.

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