TY - CONF

T1 - Recent Antenna Calibration Developments at IFE

AU - Kröger, Johannes

AU - Breva, Yannick

AU - Kersten, Tobias

AU - Schön, Steffen

PY - 2024/7/1

Y1 - 2024/7/1

N2 - For precise and accurate GNSS-based positioning, it is mandatory to take antenna Phase Center Corrections (PCC) into account. The frequency- and antenna-dependent PCC are provided as a grid with a typical step size of 5° elevation and azimuth angles in the Antenna Exchange (ANTEX) format as individual calibrations or alternatively as type-mean values. At the Institut für Erdmessung (IfE) - an IGS accepted calibration facility - PCC are estimated in the field by use of a robot and real GNSS signals. In the past, the estimation approach has been extended to newer frequencies (e.g. GPS L5) and GNSS. More recently, an alternative estimation approach has been implemented and several concepts for comparing different PCC sets, i.e. PCC differences (dPCC), have been developed.In our contribution, we present the newest developments for estimating and comparing multi-GNSS PCC. For the estimation approach, this includes the usage of hemispherical harmonics (HSH) instead of spherical harmonics for parametrizing and estimating PCC. Due to the limited availability of observations on the lower antenna hemisphere during the calibration process, the utilization of SH results in an ill-conditioned normal equation system (NES) when no additional restrictions are implemented. By using an adapted version of HSH, so that the associated Legendre polynomials are shifted to the interval of obtainable elevation angles on the antenna hemisphere (taking also the available negative elevation angles into account), a stable NES is achieved. This also allows analysing the obtained formal standard deviations of the gridded PCC values. Here, a special focus lies on results from different frequencies and multiple systems.In addition, comparison strategies proposed by our working group in previous work are presented. This includes the analysis of different PCC values on pattern level with characteristic values, as well as the use of a standardized simulation approach. It allows assessing the impact of multi-GNSS dPCC on topocentric station coordinate differences, tropospheric and clock estimates w.r.t. changing processing parameters. Based on these strategies, we present possible approaches for selection criteria based on which PCC values from different calibration facilities could be included into the IGS ANTEX file.

AB - For precise and accurate GNSS-based positioning, it is mandatory to take antenna Phase Center Corrections (PCC) into account. The frequency- and antenna-dependent PCC are provided as a grid with a typical step size of 5° elevation and azimuth angles in the Antenna Exchange (ANTEX) format as individual calibrations or alternatively as type-mean values. At the Institut für Erdmessung (IfE) - an IGS accepted calibration facility - PCC are estimated in the field by use of a robot and real GNSS signals. In the past, the estimation approach has been extended to newer frequencies (e.g. GPS L5) and GNSS. More recently, an alternative estimation approach has been implemented and several concepts for comparing different PCC sets, i.e. PCC differences (dPCC), have been developed.In our contribution, we present the newest developments for estimating and comparing multi-GNSS PCC. For the estimation approach, this includes the usage of hemispherical harmonics (HSH) instead of spherical harmonics for parametrizing and estimating PCC. Due to the limited availability of observations on the lower antenna hemisphere during the calibration process, the utilization of SH results in an ill-conditioned normal equation system (NES) when no additional restrictions are implemented. By using an adapted version of HSH, so that the associated Legendre polynomials are shifted to the interval of obtainable elevation angles on the antenna hemisphere (taking also the available negative elevation angles into account), a stable NES is achieved. This also allows analysing the obtained formal standard deviations of the gridded PCC values. Here, a special focus lies on results from different frequencies and multiple systems.In addition, comparison strategies proposed by our working group in previous work are presented. This includes the analysis of different PCC values on pattern level with characteristic values, as well as the use of a standardized simulation approach. It allows assessing the impact of multi-GNSS dPCC on topocentric station coordinate differences, tropospheric and clock estimates w.r.t. changing processing parameters. Based on these strategies, we present possible approaches for selection criteria based on which PCC values from different calibration facilities could be included into the IGS ANTEX file.

M3 - Poster

T2 - IGS Symposium and Workshop 2024

Y2 - 1 July 2024 through 5 July 2024

ER -