A new paper published in the online journal GPS Solutions outlines and assesses the most recent changes made to Geoscience Australia’s AUSPOS 3.0 GPS data processing service.

The paper — Analysis of the AUSPOS v3.0 positioning service after alignment to ITRF2020 — has been authored by Thomas Maile, Salim Masoumi, Carl Wang, Anna Riddell and Simon McClusky, all from Geoscience Australia (GA).

Following the introduction of AUSPOS version 3.0 in mid-2024, computation of coordinates is now done with respect to the ITRF2020 reference frame rather than the earlier ITRF2014.

According to GA, AUSPOS 3.0 provides improved quality of solutions due to the implementation of Bernese v5.2 software, more available reference sites for network calculations, updated antenna calibration values for ground receiver antenna types, and a more precise/advanced ocean tide loading model.

In the paper’s plain language summary, the authors write that “The new version of AUSPOS (v3.0) was tested against the previous version (v2.4) to make sure it produces consistent results when providing coordinates that align with Australia’s national datum, GDA2020. The tests showed that the new system performs well and provides accurate coordinates, similar to the previous system but with enhanced accuracy and reliability.”

Providing more detail in the paper’s conclusion section, they write that “This comparison study confirmed that the upgrade of AUSPOS to v3.0 has no significant impact on the estimated GDA2020 coordinates for most user sites. Whilst some differences between GDA2020 solutions derived from the AUSPOS v2.4 and v3.0 do exist, less than 0.08% of the differences observed in the NGCA [National Geodetic Campaign Archive] testing were statistically significant.”

“Improvements in the position and velocity estimation for the reference CORS and more available CORS for network selection are the two main improvements to the AUSPOS system, and these improvements were responsible for most of the differences in the coordinates estimated by AUSPOS v3.0 compared to v2.4. Furthermore, updates in the standards and models used in IGS20 as well as updates to Bernese v5.2 software are also improvements implemented in the AUSPOS v3.0 system that likely improve the AUSPOS solutions.”

The authors go on to caution that “identical repeatability of GDA2020 or ITRF coordinates after such a significant reference frame upgrade is not realistic. When comparing differences in positions derived from AUSPOS v2.4 and v3.0 using the same GPS measurements as input, users are encouraged to consider the positional uncertainty of the estimated coordinates.”

“Ultimately, if a user is seeking the most consistent and reliable results from AUSPOS, they must also take care in their GPS survey and ensure that they record the highest possible quality of GPS measurements.”

It is expected that a further update to AUSPOS will be released this year, including introduction of v5.4 of the Bernese multi-GNSS data processing software.