A Global Collaboration to Enhance GNSS Receiver Antenna Calibration: The IGS Antenna Ring Campaign

Achieving a high-precision geodetic spatial reference depends on a thorough understanding of the equipment-specific sources of error of phase centre corrections (PCCs) of Global Navigation Satellite System (GNSS) receiver antennas. GNSS station operators and network analysers are constantly challenged regarding consistent PCCs, such as in the latest IGS Repo3 project. The challenges are, on the one hand, that not for all antennas in the network multi-GNSS calibrations are available. On the other hand, not all antennas are individually calibrated, so that type mean combinations with individual PCCs have to be used.

Even small differences between PCCs can significantly affect position accuracy, troposphere modelling, and GNSS time and frequency transfer. Such deviations manifest differently depending on used hardware, software, and data processing approach. A generalised and easily accessible benchmark for assessing the quality of PCCs remains difficult to find. There is a lack of easy-to-apply and common quality assessments of PCCs when comparing individual calibrations versus a type mean and results from the various calibration facilities and calibration methods among each other.

In response to this challenge, a global initiative involving nine calibration organisations has launched a comprehensive ring calibration campaign. By sharing six constructionally different antenna samples for calibration and presenting the subsequent results, this collaborative effort aims to enhance (1) the consistency of calibration methods and facilities, (2) develop a validation strategy, and (3) provide insights into the stability of receiver antenna calibrations.

This contribution provides an overview of the current status of this campaign, initiated one and a half years ago, outlines the calibration and evaluation concept for carrier phase patterns. First initial results from consulting contributors are presented and the roadmap towards a standardised, robust quality assessment framework for PCCs will be covered.