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Elevation only vs full PCC models - the impact on positioning

Dawidowicz Karol, Baryła Radosław

GIS Odyssey Journal

2025

Vol. 5, no. 1

213--226

Antenna phase center corrections (PCC) are now mandatory for high-accuracy Global Navigation Satellite System (GNSS) applications. Such corrections are being created nowadays using an anechoic chamber or an outdoor robot calibration method. Based on these two methods, PCCs are created in the function of the zenith angle and azimuth of the incoming GNSS signal. However, some antennas still lack complete PCC as both approaches are time and money-consuming. In the case of some antennas, mostly low-cost ones, no real phase center location information is provided. For another group of antennas, so-called elevation-only PCC derived from relative outdoor calibration is available. Elevation-only PCC, after transformation, could be utilized together with full PCC models in common GNSS observation processing. In the publication, the authors analyzed the differences resulting from the use of elevation-only instead of full PCC models. Values of such differences can be treated as a bias introduced into the solution due to the use of simplified PCCs. The results obtained prove that in the analyzed case study, such biases are negligible and do not exceed 1 mm in any case.

Analysis of comparability of PCV in surveying-grade GNSS antenna - Topcon HIPER-VR case study

Baryła Radosław, Dawidowicz Karol

Artificial Satellites : Journal of Planetary Geodesy

2024

Vol. 59, No. 3

87--99

It is well known that the phase center of a Global Navigation Satellite System (GNSS) antenna is not a stable point. For any given GNSS antenna, the phase center will change with the direction of the incoming signal from a satellite, as well as the frequency. Ignoring these phase center variations (PCVs) in GNSS data processing can lead to notable errors, especially in vertical position component determination. To avoid the problem, antenna PCV together with the phase center offset (PCO) information are recommended to be used in GNSS observation processing. We currently distinguish between individual and type-mean phase center correction (PCC) models. These models describe the variations in the phase center of the antenna as a function of the elevation angle and azimuth. In general, the primary difference between individual and type-mean models lies in their specificity. Individual models are highly precise but are valid only for a particular antenna model, while the type-mean models are more general and can be applied to a broad range of antennas of the same type, but may suffer from a lower level of precision. This paper aims to analyze the comparability of PCV in surveyinggrade GNSS antennas. For the analyses, we propose to use an originally designed bench with precisely defined relative positions of the seven antenna mounting points. Preliminary studies have been performed using GPS observations on L1 and L2 frequencies recorded by seven Topcon HIPER-VR antennas. The results proved that the comparability of PCV for this antenna is high. The position error did not exceed 3 mm. It could be assumed that the type-mean PCC model could describe PCV all antennas of this type with good accuracy.