Dear Colleagues,

Precise Point Positioning (PPP) has evolved as a serious Global Positioning System (GPS) processing strategy since its development in the late 1990s. Benefitting from 32 GPS satellites on orbit, the availability of high-accuracy satellite orbit and clock products, and modern bias modelling methods, PPP has been able to produce comparable results to differential network processing strategies while being extremely computationally efficient and user friendly.

The station-wise resolution of integer ambiguities (AR) was achieved through the estimation of uncalibrated hardware delays in the late 2000s. PPP-AR strategies improved the overall performance of PPP and allowed, for the first time, the computation of high-accuracy satellite orbit and clock products based entirely on undifferenced observations. At the same time, the world has entered an environment with multiple Global Navigation Satellite System (GNSS) constellations; besides GPS and GLONASS, systems have been developed in China (BeiDou), Europe (Galileo), Japan (QZSS), and India (IRNSS) and have now reached a state of near completion. Much effort has been undertaken to develop PPP-AR strategies for these new GNSS and combinations thereof, which has involved the estimation of a number of biases (differential code and phase biases, inter-frequency biases, inter-system biases, and hardware biases) to allow consistent processing to be carried out using several GNSS and to reconstruct the integer character of the phase ambiguities.

This Special Issue aims to attract scientific contributions in the field of PPP with multi-GNSS observations and may include studies of PPP-AR, the generation of satellite orbit and clock products using undifferenced observations, bias products for PPP-AR, and new algorithms and applications.

Prof. Dr. Felix Norman Teferle
Dr. Addisu Hunegnaw
Prof. Dr. Jianghui Geng
Guest Editors

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• global navigation satellite system
• precise point positioning
• integer ambiguity resolution
• undifferenced GNSS
• high-precision GNSS
• differential code biases
• differential phase biases
• inter-frequency biases
• uncalibrated hardware biases
• real-time PPP