Experimental Multi-GNSS Combinations

Figures and Statistics from the IGS experimental Multi-GNSS Orbit Combination

Experimental Multi-GNSS Combination

In line with the IGS Multi-GNSS Experiment (MGEX) and with the increasing trend in the availability of Multi-GNSS products through different analysis centres, the IGS Analysis Centre Coordinator (IGS ACC) is trialling an experimental MGEX orbit combination by adapting the existing combination software. The intention is to compare how the next version of the combination software will perform against the existing software; therefore, the MGEX orbit combinations are not considered to be the final products at the moment. These combinations also aim at comparing how different analysis centres perform considering the MGEX products. They also encourage more contribution from the analysis centres to the MGEX products.

The experimental MGEX products are made available on a weekly basis, with a delay up to 13 to 20 days, similar to the final combination. Since the purpose of the experimental phase is to include as many MGEX submissions as possible, the combination includes rapid MGEX submissions as well as final submissions combined together. As the eventual aim is to include as many submissions as possible in the combination, the current GPS-only (and GLONASS-only) submissions are also included as long as there is a maximum of one submission from each AC for each constellation. In case of the ACs having both GPS-only (or GLONASS-only) and MGEX submissions, only the MGEX submission is used and the GPS-only or GLONASS-only solution is only used for comparison.

The AC SINEX transformations with respect to the current IGS reference frame are not applied in the current Multi-GNSS orbit combinations. The orbit combination is performed separately for each constellation, using the same weighted average approach used in the current software for GPS orbit combination. The results from different constellations are then compiled into one summary file and one sp3 file available HERE. Currently, only orbit combinations are available for the Multi-GNSS products. The plots below showing the Weighted RMS (WRMS) of the the individual AC orbit solutions (including MGEX solutions) with respect to the combined orbits, as well as those showing the estimated transformation parameters between individual ACs and the IGS combined orbits, are useful for assessing the repeatabilities of the MGEX products by different analysis centres.