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In the context of GPS the most prominent correction introduced by general relativity is gravitational time dilation: the clocks located deeper in the gravitational potential well (i.e. closer to the attracting body) tick slower. Satellite clocks are slowed by their orbital speed but sped up by their distance out of the Earth's gravitational well.
GPS Block III is the first series of third-generation GPS satellites, incorporating new signals and broadcasting at higher power levels. In September 2016, the United States Air Force awarded Lockheed Martin a contract option for two more Block III satellites, setting the total number of GPS III satellites to ten. [ 22 ]
Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit . There are many different ways to mathematically describe the same orbit, but certain schemes, each consisting of a set of six parameters, are commonly used in ...
The GPS date and time, and the satellite's status. The ephemeris: precise orbital information for the transmitting satellite. The almanac: status and low-resolution orbital information for every satellite. An ephemeris is valid for only four hours, while an almanac is valid–with little dilution of precision–for up to two weeks. [7]
The basic orbit determination task is to determine the classical orbital elements or Keplerian elements, ,,,,, from the orbital state vectors [,], of an orbiting body with respect to the reference frame of its central body. The central bodies are the sources of the gravitational forces, like the Sun, Earth, Moon and other planets.
is the orbital inclination; is the orbit's semi-major axis; is the orbital eccentricity; These two effects must cancel out after a set orbital revolutions and (sidereal) days. Hence, equating the elapsed time to the orbital period of the satellite and combining the above two equations yields an equation which holds for any orbit that is a ...
GNSS systems that provide enhanced accuracy and integrity monitoring usable for civil navigation are classified as follows: [5] GNSS-1 is the first generation system and is the combination of existing satellite navigation systems (GPS and GLONASS), with Satellite Based Augmentation Systems (SBAS) or Ground Based Augmentation Systems (GBAS). [5]
The longitude of the ascending node, also known as the right ascension of the ascending node, is one of the orbital elements used to specify the orbit of an object in space. Denoted with the symbol Ω , it is the angle from a specified reference direction, called the origin of longitude , to the direction of the ascending node (☊), as ...