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GPS receivers that use the L5 band have much higher accuracy of 30 centimeters (12 in), while those for high-end applications such as engineering and land surveying are accurate to within 2 cm (3 ⁄ 4 in) and can even provide sub-millimeter accuracy with long-term measurements.
The United States' Global Positioning System (GPS) consists of up to 32 medium Earth orbit satellites in six different orbital planes. The exact number of satellites varies as older satellites are retired and replaced. Operational since 1978 and globally available since 1994, GPS is the world's most utilized satellite navigation system.
GPS encodes this information into the navigation message and modulates it onto both the C/A and P(Y) ranging codes at 50 bit/s. The navigation message format described in this section is called LNAV data (for legacy navigation). The navigation message conveys information of three types: The GPS date and time, and the satellite's status.
Geopositioning can be referred to both global positioning and outdoor positioning, using for example GPS, and to indoor positioning, for all the situations where satellite GPS is not a viable option and the localization process has to happen indoors. For indoor positioning, tracking and localization there are many technologies that can be used ...
GPS signals can also be affected by multipath issues, where the radio signals reflect off surrounding terrain; buildings, canyon walls, hard ground, etc. These delayed signals cause measurement errors that are different for each type of GPS signal due to its dependency on the wavelength.
This glossary of aerospace engineering terms pertains specifically to aerospace engineering, its sub-disciplines, and related fields including aviation and aeronautics. For a broad overview of engineering, see glossary of engineering .
A major subclass is made of geopositioning systems, used for determining an object's position with respect to Earth, i.e., its geographical position; one of the most well-known and commonly used geopositioning systems is the Global Positioning System (GPS) and similar global navigation satellite systems (GNSS).
The GPS system space segment is composed of 24 to 32 satellites in medium Earth orbit at an altitude of approximately 20,200 km (12,600 mi). The satellites are in six specific orbits and transmit highly accurate time and satellite location information which can be used to derive distances and calculate position.