PPPLib: An open-source software for precise point positioning using GPS, BeiDou, Galileo, GLONASS, and QZSS with multi-frequency observations

Precise Point Positioning Library (PPPLib) is a multi-GNSS data processing software designed to process multi-frequency data from GPS, BeiDou, Galileo, GLONASS, and QZSS. PPPLib is written in the C/C++ programming language. It can compile and run on both Linux and Windows operating systems. PPPLib mainly performs precise point positioning from single to triple frequency based on either ionospheric-free or uncombined observations. Moreover, it solves for abundant parameters, including position, tropospheric delay, ionospheric delay, and ambiguity information. Useful scripts and visualization tools are also provided for data download, batch processing, or solution presentation. We give a preliminary review, including positioning accuracy and convergence time of PPP using dual-frequency, ionospheric-free from single system to multi-GNSS, to show the working status of the current version of the software. In addition, the software also supports post-processing kinematic mode and INS/GNSS loosely coupled mode for kinematic positioning.