Applying phase center corrections also to code observables? – A PPP case study

Abstract

Consistent and reliable receiver antenna calibration sets are an essential prerequisite for precise geodetic reference frames. In the context of the igs3-reprocessing campaign and the realisation of a new international terrestrial reference frame (ITRF20) using multi-GNSS, receiver antenna phase centre correction (PCC) sets play a key role. However, the consistency between different PCC realisations and the exchange of PCCs are today still a challenging task.

In this contribution, we present results of our developed strategy for the characterisation of receiver antenna calibration sets. We emphasise the need of consistency between individual PCCs resulting from different calibration strategies and various realisations (igs14, igs20 and igsR3_2077). We discuss the need of defining the reception point for code and carrier phase observation, i.e. should PCC also be applied to code? Based on precise point positioning (PPP) we will show that the consistency of modelling both observation types in PPP is required and the differences are not only related to the residuals but also to the receiver clock estimates. We analyse this challenge at selected EUREF Permanent Network (EPN) sites, examining the receiver antenna pattern and the geographical location, as this also has a crucial role. The consistency of the reference point between code and carrier phase observations has additional effects on the parameters, as they are linked by the ionosphere free linear-combination. Depending on the type of receiver antenna, effects on the receiver clock estimates and ambiguities of up to 8 mm and systematic effects on PPP code post-fit residuals have been found.