The GREAT (GNSS+ REsearch, Application and Teaching) software

is designed and developed at Wuhan University for scientific and engineering application and teaching in geodesy and navigation fields. It is written in standard C++. It supports real-time precise orbit and clock determination, LEO augmented GNSS, multi-GNSS biases estimation, PPP-AR/PPP-RTK, GNSS+INS+VISION+LiDAR, and GNSS+SLR+VLBI integrated processing.

Features and Highlights

Modularity

The architecture is designed with object-oriented idea, and various functions of the software are realized by object-oriented programming language C++.

Reusability and extensibility

Each function module provides complete and sufficient interfaces, which are convenient for developers to expand functions based on existing modules.

Multi-functioning

Advanced algorithms and models, supporting orbit and clock determination, PPP / PPP-RTK, IMU, VISION , LiDAR and other sensors of integrated / non combined, multi-frequency and multi-system, fixed ambiguity and other processing strategies.

Standardization

Written in Google code style; implemented using C++11 and its standard library functions; using XML as configuration file

Maintenance friendly

Use a cross platform installation (compilation) tool CMake to organize the compiled code, and use the open source version control system Git to manage different code versions.

Cross platform

Written in standard C + + 11, it supports mainstream computer operating systems such as windows, Linux, UNIX and MacOS.

Overall Framework

Typical Function

GNSS Precise Orbit/Clock

Multi-GNSS Precise orbit determination in multi-frequency and Ionospheric-free and undifferenced-and-uncombined observation models are supported; Multi-GNSS precise clock determination in real-time

LEO Precise Science Orbit

Reduced-dynamic orbit with ambiguity resolution for LEO satellites, including GRACE Follow-on, Swarm, Jason-3 and Sentinel-3 and Processing satellite laser ranging data is supported

GNSS Precise Positioning

Multi-GNSS Precise postioning is capable to process multi-GNSS data(GPS, GLONASS, Galileo, BDS, QZSS, etc.) in multi-frequency and supports both standalone PPP and short/long-baseline RTK/PPK.

Bias Estimation

Support estimation of Multi-GNSS and multi-frequency uncalibrated phase delay (UPD) ,Code and phase observable-specific signal bias for multiple GNSS constellations

GNSS/INS

Support multiple IMU data input formats and Provide two combined solutions, including Loosely Coupled Integration(LCI), Tightly Coupled Integration(TCI)

GNSS/INS/VISION

GNSS/INS/VISION loosely,tightly,semi tightly coupled integration