Abstract
Precise Point Positioning (PPP), as a global precise positioning technique, suffers from relatively long convergence times, hindering its ability to be the default precise positioning technique. Reducing the PPP convergence time is a must to reach global precise positions, and doing so in a few minutes to seconds can be achieved thanks to the additional frequencies that are being broadcast by the modernized GNSS constellations. Due to discrepancies in the number of signals broadcast by each satellite/constellation, it is necessary to have a model that can process a mix of signals, depending on availability, and perform ambiguity resolution (AR), a technique that proved necessary for rapid convergence. This manuscript does so by expanding the uncombined Decoupled Clock Model to process and fix ambiguities on up to three frequencies depending on availability for GPS, Galileo, and BeiDou. GLONASS is included as well, without carrier-phase ambiguity fixing. Results show the possibility of consistent quasi-instantaneous global precise positioning through an assessment of the algorithm on a network of global stations, as the 67th percentile solution converges below 10 cm horizontal error within 2 min, compared to 8 min with a triple-frequency solution, showing the importance of having a flexible PPP-AR model frequency-wise. In terms of individual datasets, 14% of datasets converge instantaneously when mixing dual- and triple-frequency measurements, compared to just 0.1% in that of dual-frequency mode without ambiguity resolution. Two kinematic car datasets were also processed, and it was shown that instantaneous centimetre-level positioning with a moving receiver is possible. These results are promising as they only rely on ultra-rapid global satellite products, allowing for instantaneous real-time precise positioning without the need for any local infrastructure or prior knowledge of the receiver’s environment.
Highlights
The Precise Point Positioning (PPP) technique noticeably evolved since its early conception
The effect of ambiguity resolution (AR) is limited when it comes to the vertical component when looking at the 100th and 95th percentiles, as the improvements to the convergence time and rms are not as significant as for the horizontal component
Ambiguity resolution proved to be an important tool to level-up PPP towards instantaneous centimetre positioning
Summary
The Precise Point Positioning (PPP) technique noticeably evolved since its early conception. The technique was intended as a precise positioning alternative that would reduce the computational burden in network static relative baseline processing, and would only require a stand-alone receiver [1,2], as opposed to, e.g., Real-Time Kinematics (RTK), which requires the presence of and communication with nearby base stations [3,4]. Because of the latter technique requiring local infrastructure to provide precise positioning, PPP is becoming the de facto global precise positioning technique, as it only requires globally estimated satellite corrections [5]. Ambiguity resolution proved to be a valuable tool in reducing convergence time [8,9,10], as making use of the integer nature of the ambiguities allows for faster fixing to their correct values instead of waiting for them to converge.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call