A guide to using GRG IGS products

Abstract:

The CNES-CLS IGS Analysis Center is being providing “final” GNSS orbit and clock products for a decade. The processing strategy is based on undifferentiated observations and the so called Integer Recovery Clock approach. So these products are suitable for Precise Point Positioning using phase measurements with ambiguity resolution (PPP-AR). Numerous users are exploiting this property for a wide variety of applications like atomic clock comparison, scientific mobile tracking or earth deformation investigations. Nevertheless, getting the best possible PPP-AR solution is challenging and requires to take into account several subtle aspects related to how the orbit and clock solutions have been produced and have to be used.

This presentation recalls how the IRC approach has been implemented into the GINS software and the corresponding definition of the various terms involved like satellite and receiver clock bias. The need of consistency with the models (e.g. reference frame, satellite attitude model) used to generate these GRG products is also discussed.

In 2020, the CNES-CLS group has participated into a reprocessing effort resulting in a full and consistent set of products including IRC satellite clocks and hardware (“wide-lane”) biases since 2000 for GPS and since 2017 for Galileo as well as satellite attitude ORBEX files. The aim of this presentation is to facilitate and encourage the use of these products.