BCAL/UFPR: The GNSS Antenna Calibration Service of Latin America

The usage of individual calibration values for GNSS (Global Navigation Satellite Systems) antennas is of fundamental importance for state-of-the-art GNSS positioning at millimeter accuracy level, especially concerning precise height determination. In Brazil, the awareness of the user community regarding this important error source has to be sharpened. In contrast to Europe, where manifold research is carried out focusing on antenna calibration and different agencies provide calibration services, in Latin America the users have to be sensitized with respect to receiver antenna handling. Therefore, the first Latin American GNSS antenna calibration basis BCAL/UFPR (Baseline Calibration Station for GNSS Antennas at UFPR) was established at the Federal University of Paraná (UFPR; Curitiba, Paraná, Brazil) in close cooperation with the Geodetic Institute of the Karlsruhe Institute of Technology (Karlsruhe, Germany). The BCAL/UFPR is actually equipped with three pillars and enables the determination of antenna parameters applying the relative field calibration approach. The antenna modeling parameters are derived at absolute level, because the reference antenna (3D choke ring antenna type) was calibrated absolutely by Geo++ (Garbsen, Germany). In this context, five antennas of the same model (Trimble Zephyr GNSS Geodetic II) were calibrated at BCAL/UFPR. The goal of the case study is to verify the difference between individual parameters determined at BCAL/UFPR and mean parameters published by the NGS (National Geodetic Service, USA). This article presents information related to BCAL/UFPR and discusses the results of recent calibration investigations.