CATREF – Combination and Analysis of Terrestrial Reference Frames

CATREF is a scientific software package developed for the rigorous combination and analysis of terrestrial reference frame solutions. It is widely used to combine individual technique-specific solutions (e.g., GNSS, VLBI, SLR, DORIS) into a consistent multi-technique International Terrestrial Reference Frame (ITRF) solution.

In geodesy, CATREF provides the mathematical framework for estimating station coordinates, velocities, and geophysical parameters while applying appropriate constraints and combination strategies. It is a key tool in the realization of global terrestrial reference frames, ensuring long-term stability, consistency between techniques, and high-precision global positioning.

More info: https://itrf.ign.fr/en/solutions/combination