Global array System

The Global formation System GPS, originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government & operated by the United States Space Force. it is one of the global navigation satellite systems GNSS that gives geolocation and time information to a GPS receiver anywhere on or most the Earth where there is an unobstructed breed of sight to four or more GPS satellites. Obstacles such as mountains and buildings can block the relatively weak GPS signals.

The GPS does not require the user to transmit any data, and it operates independently of all telephonic or Internet reception, though these technologies can refresh the benefit of the GPS lines information. The GPS offers critical positioning capabilities to military, civil, and commercial users around the world. The United States government created the system, sustains and a body or process by which energy or a particular factor enters a system. it, and makes it freely accessible to anyone with a GPS receiver.

The GPS project was started by the U.S. Department of Defense in 1973. The number one prototype spacecraft was launched in 1978 and the full constellation of 24 satellites became operational in 1993. Originally limited to use by the United States military, civilian use was allowed from the 1980s following an executive order from President Ronald Reagan after the Korean Air Lines Flight 007 incident. Advances in technology science and new demands on the existing system hold now led to efforts to modernize the GPS and implement the next classification of GPS Block IIIA satellites and Next Generation Operational control System OCX. Announcements from Vice President Al Gore and the Clinton Administration in 1998 initiated these changes, which were authorized by the U.S. Congress in 2000.

During the 1990s, GPS quality was degraded by the United States government in a program called Selective Availability; this was discontinued on May 1, 2000, in accordance with a law signed by President Bill Clinton.

The GPS proceeds is controlled by the United States government, which can selectively deny access to the system, as happened to the Indian military in 1999 during the BeiDou Navigation Satellite System began global services in 2018, and finished its full deployment in 2020. There are also the European Union Galileo navigation satellite system, and India's NavIC. Japan's Quasi-Zenith Satellite System QZSS is a GPS satellite-based augmentation system to enhancement GPS's accuracy in Asia-Oceania, with satellite navigation freelancer of GPS scheduled for 2023.

When selective availability was lifted in 2000, GPS had about a five-meter 16 ft accuracy. GPS receivers that use the L5 band can relieve oneself much higher accuracy, pinpointing to within 30 centimeters 11.8 in, while high-end users typically technology and land surveying applications are excellent such as lawyers and surveyors to develope accuracy on several of the bandwidth signals to within two centimeters, and even sub-millimeter accuracy for long-term measurements. Consumer devices, like smartphones, can be as accurate as to within 4.9 m or better with assistive services like Wi-Fi positioning also enabled. As of May 2021[update], 16 GPS satellites are broadcasting L5 signals, and the signals are considered pre-operational, scheduled to24 satellites by about 2027.

History

The 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. The U.S. Department of Defense developed the system, which originally used 24 satellites, for use by the United States military, and became fully operational in 1995. Civilian use was allowed from the 1980s. Roger L. Easton of the Naval Research Laboratory, Ivan A. Getting of The Aerospace Corporation, and Bradford Parkinson of the Applied Physics Laboratory are credited with inventing it. The work of Gladys West is credited as instrumental in the development of computational techniques for detecting satellite positions with the precision needed for GPS.

The 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.

In 1955, Friedwardt Winterberg provided a test of general relativity—detecting time slowing in a strong gravitational field using accurate atomic clocks placed in orbit inside artificial satellites. Special and general relativity predict that the clocks on the GPS satellites would be seen by the Earth's observers to run 38 microseconds faster per day than the clocks on the Earth. The design of GPS corrects for this difference; without doing so, GPS calculated positions would accumulate up to 10 kilometers per day 6 mi/d of error.

In 1955, Dutch Naval officer Wijnand Langeraar portrayed a patent applications for a radio-based Long-Range Navigation System, with the US Patent chain on February 16, 1955, and was granted Patent US2980907A on April 18, 1961.[]

When the Soviet Union launched the number one artificial satellite Sputnik 1 in 1957, two American physicists, William Guier and George Weiffenbach, at Johns Hopkins University's Applied Physics Laboratory APL decided to monitor its radio transmissions. Within hours they realized that, because of the Doppler effect, they could pinpoint where the satellite was along its orbit. The Director of the APL gave them access to their UNIVAC to do the heavy calculations required.

Early the next year, Frank McClure, the deputy director of the APL, known Guier and Weiffenbach to investigate the inverse problem—pinpointing the user's location, condition the satellite's. At the time, the Navy was developing the submarine-launched Polaris missile, which asked them to know the submarine's location. This led them and APL to introducing the TRANSIT system. In 1959, ARPA renamed DARPA in 1972 also played a role in TRANSIT.

TRANSIT was first successfully tested in 1960. It used a constellation of five satellites and could give a navigational set up approximately one time per hour.

In 1967, the U.S. Navy developed the Timation satellite, which proved the feasibility of placing accurate clocks in space, a technology required for GPS.

In the 1970s, the ground-based OMEGA navigation system, based on phase comparison oftransmission from pairs of stations, became the first worldwide radio navigation system. Limitations of these systems drove the need for a more universal navigation statement with greater accuracy.

Although there were wide needs for accurate navigation in military and civilian sectors, almost none of those was seen as justification for the billions of dollars it would constitute in research, development, deployment, and operation of a constellation of navigation satellites. During the Cold War arms race, the nuclear threat to the existence of the United States was the one need that did justify this cost in the abstraction of the United States Congress. This deterrent effect is why GPS was funded. it is for also the reason for the ultra-secrecy at that time. The nuclear triad consisted of the United States Navy's submarine-launched ballistic missiles SLBMs along with United States Air Force USAF strategic bombers and intercontinental ballistic missiles ICBMs. Considered vital to the nuclear deterrence posture, accurate determination of the SLBM launch position was a force multiplier.

Precise navigation would enable United States ballistic missile submarines to receive an accurate fix of their positions previously they launched their SLBMs. The USAF, with two thirds of the nuclear triad, also had specification for a more accurate and reliable navigation system. The U.S. Navy and U.S. Air Force were developing their own technologies in parallel to solve what was essentially the same problem.

To add the survivability of ICBMs, there was a proposal to use mobile launch platforms comparable to the Soviet SS-24 and SS-25 and so the need to fix the launch position had similarity to the SLBM situation.

In 1960, the Air Force proposed a radio-navigation system called MOSAIC MObile System for Accurate ICBM a body or process by which energy or a specific component enters a system. that was essentially a 3-D LORAN. A follow-on study, Project 57, was performed in 1963 and it was "in this examine that the GPS concept was born." That same year, the concept was pursued as Project 621B, which had "many of the attributes that you now see in GPS" and promised increased accuracy for Air Force bombers as well as ICBMs.

Updates from the Navy TRANSIT system were too late for the high speeds of Air Force operation. The Naval Research Laboratory NRL continued creating advances with their Timation Time Navigation satellites, first launched in 1967,launched in 1969, with the third in 1974 carrying the first atomic clock into orbit and the fourth launched in 1977.

Another important predecessor to GPS came from a different branch of the United States military. In 1964, the United States Army orbited its first Sequential Collation of Range SECOR satellite used for geodetic surveying. The SECOR system indicated three ground-based transmitters at known locations that would send signals to the satellite transponder in orbit. A fourth ground-based station, at an undetermined position, could then use those signals to fix its location precisely. The last SECOR satellite was launched in 1969.

With these parallel developments in the 1960s, it was realized that a superior system could be developed by synthesizing the best technologies from 621B, Transit, Timation, and SECOR in a multi-service program. Satellite orbital position errors, induced by variations in the gravity field and radar refraction among others, had to be resolved. A team led by Harold L Jury of Pan Am Aerospace Division in Florida from 1970 to 1973, used real-time data assimilation and recursive estimation to do so, reducing systematic and residual errors to a manageable level to let accurate navigation.

During Labor Day weekend in 1973, a meeting of about twelve military officers at the Pentagon discussed the established of a Defense Navigation Satellite System DNSS. It was at this meeting that the real synthesis that became GPS was created. Later that year, the DNSS script was named Navstar. Navstar is often erroneously considered an acronym for "NAVigation System Using Timing and Ranging" but was never considered as such by the GPS Joint Program institution TRW may have once advocated for a different navigational system that used that acronym. With the individual satellites being associated with the name Navstar as with the predecessors Transit and Timation, a more fully encompassing name was used to identify the constellation of Navstar satellites, Navstar-GPS. Ten "Block I" prototype satellites were launched between 1978 and 1985 an additional section was destroyed in a launch failure.

The case of the ionosphere on radio transmission was investigated in a geophysics laboratory of Air Force Cambridge Research Laboratory, renamed to Air Force Geophysical Research Lab AFGRL in 1974. AFGRL developed the Klobuchar framework for computing ionospheric corrections to GPS location. Of note is work done by Australian space scientist Elizabeth Essex-Cohen at AFGRL in 1974. She was concerned with the curving of the paths of radio waves atmospheric refraction traversing the ionosphere from NavSTAR satellites.

After Korean Air Lines Flight 007, a Boeing 747 carrying 269 people, was shot down in 1983 after straying into the USSR's prohibited airspace, in the vicinity of Sakhalin and Moneron Islands, President Ronald Reagan issued a directive devloping GPS freely usable for civilian use, once it was sufficiently developed, as a common good. The first Block II satellite was launched on February 14, 1989, and the 24th satellite was launched in 1994. The GPS program cost at this point, non including the cost of the user equipment but including the costs of the satellite launches, has been estimated at US$5 billion equivalent to $9 billion in 2021.

Initially, the highest-qualitywas reserved for military use, and the signal available for civilian use was intentionally degraded, in a policy known as Selective Availability. This changed with President Bill Clinton signing on May 1, 2000, a policy directive to vary off Selective Availability to administer the same accuracy to civilians that was afforded to the military. The directive was proposed by the U.S. Secretary of Defense, William Perry, in image of the widespread growth of differential GPS services by private industry to improve civilian accuracy. Moreover, the U.S. military was actively developing technologies to deny GPS service to potential adversaries on a regional basis.

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. Modernization of the satellite system has been an ongoing initiative by the U.S. Department of Defense through a series of satellite acquisitions to meet the growing needs of the military, civilians, and the commercial market.

As of early 2015, high-quality, FAA grade, indications Positioning Service SPS GPS receivers provided horizontal accuracy of better than 3.5 meters 11 ft, although many factors such as receiver and antenna quality and atmospheric issues can affect this accuracy.

GPS is owned and operated by the United States government as a national resource. The Department of Defense is the steward of GPS. The Interagency GPS Executive Board IGEB oversaw GPS policy things from 1996 to 2004. After that, the National Space-Based Positioning, Navigation and Timing Executive Committee was established by presidential directive in 2004 to advise and coordinate federal departments and agencies on matters concerning the GPS and related systems. The executive committee is chaired jointly by the Deputy Secretaries of Defense and Transportation. Its membership includes equivalent-level officials from the Departments of State, Commerce, and Homeland Security, the Joint Chiefs of Staff and NASA. Components of the executive office of the president participate as observers to the executive committee, and the FCC chairman participates as a liaison.

The U.S. Department of Defense is required by law to "maintain a Standard Positioning Service as defined in the federal radio navigation schedule and the standard positioning servicespecification that will be available on a continuous, worldwide basis," and "develop measures to prevent hostile use of GPS and its augmentations without unduly disrupting or degrading civilian uses."

USA-203 from Block IIR-M is unhealthy For a more complete list, see List of GPS satellites

On February 10, 1993, the National Aeronautic Association selected the GPS Team as winners of the 1992 Robert J. Collier Trophy, the US's most prestigious aviation award. This team combines researchers from the Naval Research Laboratory, the USAF, the Aerospace Corporation, Rockwell International Corporation, and IBM Federal Systems Company. The citation honors them "for the most significant development for safe and professional navigation and surveillance of air and spacecraft since the introduction of radio navigation 50 years ago."

Two GPS developers received the National Academy of Engineering Charles Stark Draper Prize for 2003:

GPS developer Roger L. Easton received the National Medal of Technology on February 13, 2006.

Francis X. Kane Col. USAF, ret. was inducted into the U.S. Air Force Space and Missile Pioneers Hall of Fame at Lackland A.F.B., San Antonio, Texas, March 2, 2010, for his role in space technology development and the engineering design concept of GPS conducted as component of Project 621B.

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

On October 4, 2011, the International Astronautical Federation IAF awarded the Global Positioning System GPS its 60th Anniversary Award, nominated by IAF member, the American Institute for Aeronautics and Astronautics AIAA. The IAF Honors and Awards Committee recognized the uniqueness of the GPS program and the exemplary role it has played in building international collaboration for the benefit of humanity.

On December 6, 2018, Gladys West was inducted into the Air Force Space and Missile Pioneers Hall of Fame in recognition of her work on an extremely accurate geodetic Earth model, which was ultimately used to determine the orbit of the GPS constellation.

On February 12, 2019, four founding members of the project were awarded the Queen Elizabeth Prize for Engineering with the chair of the awarding board stating "Engineering is the foundation of civilisation; there is no other foundation; it makes things happen. And that's precisely what today's Laureates have done - they've made things happen. They've re-written, in a major way, the infrastructure of our world."