Precise Point Positioning with Ginan: Geoscience Australia’s Open-Source GNSS Analysis Centre Software

Ginan is a GNSS (Global Navigation Satellite System) analysis centre software that is currently being developed by Geoscience Australia in partnership with industry and academic partners. Ginan is fully open-source software based on the SSR (State Space Representation), PPP (Precise Point Positioning) model and is capable of computing precise positioning products, delivering real-time correction services, as well as operating as a user-driven precise positioning engine. Ginan is a modern, multi-threaded C++ application that utilises industry standard high-performance libraries such as Eigen3, and Boost. Software configuration is managed through industry standard YAML (YAML Ain’t Markup Language) files. Standard IGS (International GNSS Service) file-based products are produced, and intermediate positioning products are managed in the open-source NoSQL MongoDB database and output is through standard Radio Technical Commission for Maritime Services-3 (RTCM3), IGS-SSR and Compact SSR message streams. At its core, Ginan is a customised and optimised Kalman filter that is tightly coupled with a data pre-processor and orbit integrator, enabling both real-time processing of industry standard RTCM3 data messages streams and post-processing using IGS positioning products. The purpose of Ginan is to provide users with a unique multi-GNSS real-time processing platform capable of delivering precise positioning products to the Australian and international Positioning Navigation and Timing (PNT) community; support expert advice on navigation system performance over Australia; and provide state-of-the-art GNSS analysis centre software to universities and research organisations to enable Australia to lead in the development of geospatial technology. Ginan can be used for many geodetic and positioning activities such as computation of daily coordinate solutions, precise satellite orbit determination, computation of satellite clocks & biases, atmospheric modelling, data QA/QC and more. This paper describes the Kalman filter optimization methodology implemented in Ginan and provides benchmarking comparisons of Ginan against the International GNSS Service combined orbit and clock products.