<div>FrontierSI has been engaged by Geoscience Australia (GA) to establish a series of case studies showcasing the benefits of Positioning Australia products and services through demonstrations of precise positioning capability. This case study is the third in the series and in a collaboration with The Commonwealth Scientific and Industrial Research Organisation&nbsp;(CSIRO) it aims to explore the use of Ginan’s real-time and post-processing capabilities for determining water level height from a global navigation satellite systems (GNSS) receiver deployed on a floating pontoon on Googong Dam.</div>

<div>FrontierSI has been engaged by Geoscience Australia (GA) to establish a series of case studies showcasing the benefits of Positioning Australia products and services through demonstrations of precise positioning capability. This case study is the second in the series and in a collaboration with The Bureau of Meteorology (BOM) it aims to explore the use of Ginan’s post-processing capabilities for determining receiver altitude and atmospheric parameters from global navigation satellite systems (GNSS) observations collected from a high-altitude balloon.</div>

<div>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.</div><div><br></div><div>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.</div><div><br></div><div>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. Abstract presented at the 2024 Institute of Navigation (ION) Pacific Positioning, Navigation and Timing (PNT) Conference Honolulu, Hawaii

<div>In the third reprocessing campaign (repro3) initiated by the International GNSS Service (IGS), 11 analysis centers (ACs) reanalyzed GPS/GLONASS/Galileo observations spanning 1994–2020 for station coordinates, satellite orbits, clocks, biases and attitudes. To improve the robustness of satellite products, the IGS AC Coordinator (ACC) carried out the satellite orbit combination, and the reference satellite attitudes were computed by the Technical University of Graz (TUG). The clock/bias combination was performed by Wuhan University via the IGS “Precise Point Positioning with Ambiguity Resolution” (PPP-AR) Pilot Project using the PRIDE <i>ckcom</i> software. This article aims at reporting the clock/bias combination results in the repro3. In particular, the consistencies for the combined GPS P1–P2/Galileo C1–C5 differential code biases (DCBs) and the GPS/Galileo uncalibrated phase delays (UPDs) among contributing ACs are all better than 0.1&nbsp;ns and 0.05 cycles, respectively. As a result, the consistencies for the combined GPS/Galileo satellite clocks/biases are better than 10&nbsp;ps, equating about 3&nbsp;mm which is very close to the nominal precision of carrier-phase. In general, the Hadamard deviation and PPP-AR results confirm the higher robustness of the combined satellite clock/bias products over their original AC-specific counterparts. This is because the combined satellite clock/bias products harvest the merits of AC-specific contributions by identifying and excluding outlier solutions from the combination process.</div> <b>Citation:</b> Geng, J., Yan, Z., Wen, Q. et al. Integrated satellite clock and code/phase bias combination in the third IGS reprocessing campaign. <i>GPS Solut </i>28, 150 (2024). https://doi.org/10.1007/s10291-024-01693-9