Ch 20. GNSS Precise Point Positioning (PPP)

Overview:

GNSS PPP is a modeling and processing method with which one can compute positions with high accuracy anywhere on the globe using a single GNSS receiver. It is a logical extension of GNSS pseudorange navigation, whereby the broadcast satellite orbits and clocks are replaced with precise estimates, and the pseudorange data is complemented with the very precise carrier‐phase observations, usually on two or more frequencies so as to be able to either eliminate or estimate the ionospheric delays. The precise orbits and clocks are downloaded or obtained in real time from a number of service providers, using either the Internet or satellite links. PPP provides in addition to accurate positioning solutions, tropospheric and ionospheric delays, as well as accurate receiver clocks. To facilitate the high PPP accuracy, careful modeling of local station and environmental effects is required. As PPP does not rely, as with relative baseline positioning, on combining observations with simultaneous measurements from reference stations, it offers greater operational flexibility and is suited for areas that lack dense GNSS network infrastructure.