Precise Point Positioning
Precise Point Positioning (PPP) is a Global Navigation Satellite System (GNSS) positioning method to calculate very precise positions up to few centimeter level using a single (GNSS) receiver in a dynamic and global reference framework like International Terrestrial Reference System (ITRS). PPP methods are different from (DGNSS) positioning methods which differentiate errors using one or more reference stations with known positions. The PPP approach combines precise clocks and orbits, so-called precise ephemeris, calculated from a global network to calculate a precise position with a single receiver, which can be double or single frequency.
Historically precise positioning was associated with surveying and geodesy. It makes use of carrier-phase observables, allowing positioning precisions of a fraction of a carrier wavelength, 19 or 24 cm. It also makes use of precise ephemeris, generated by the geodetic community -- the IGS, International GNSS Service -- from measurements by a global network of tracking stations. Recently, the dissemination over the Internet in low-latency real time -- e.g., APPS, the Automatic Precise Positioning Service of NASA JPL -- has made possible to do such precise positioning also in real time, giving us the PPP technique.
With the advent of Global Navigation Satellite Systems (GNSS) such as the Global Positioning System (GPS), precise positioning has been incorporated into production processes in mining, agriculture and construction. The main application has been in machine guidance and machine automation which require high levels of precision.
Precise positioning is also increasingly used in the fields of robotics and autonomous navigation.
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