Preliminary Results of an Astri/UWM EGNSS Receiver Antenna Calibration Facility

Abstract

In 2019, the University of Warmia and Mazury in Olsztyn, in cooperation with Astri Polska, started a European Space Agency (ESA) project. The purpose of the project is the development and implementation of a field calibration procedure for a multi-frequency and multi-system global navigation satellite system (GNSS). The methodology and algorithms proposed in the project are inspired by the “Hannover” concept of absolute field receiver antenna calibration; however, some innovations are introduced. In our approach, the antenna rotation point is close to the nominal mean phase center (MPC) of the antenna, although it does not coincide with it. Additionally, a National Marine Electronics Association local time zone (NMEA ZDA) message is used to synchronize the robot with the GNSS time. We also propose some modifications in robot arm movement scenarios. Our first test results demonstrate consistent performance for the calibration strategy and calibration procedure. For the global positioning system (GPS) L1 frequency, the calibration results show good agreement with the IGS-type mean values. For high satellite elevations (20°–90°), the differences do not exceed 1.5 mm. For low elevation angles (0°–20°), the consistency of the results is worse and the differences exceed a 3 mm level in some cases.

GNSS Receiver Antenna Absolute Field Calibration System Development: Testing and Preliminary Results

“…A simplified generic GNSS observation equation for carrier phase measurements Φ i A from receiver A to satellite i, for any frequency, in units of length (meter) reads [12,16,46]:…”

“…Generally, antenna calibration is a procedure of determining the relationship between the antenna's mean phase center (MPC) and an easily accessible physical feature point, i.e., the antenna reference point (ARP), as well as determining the range corrections as a function of satellite position (azimuth and elevation angles) and signal frequency. Today, GNSS antenna calibration methods can be divided into relative field calibration, chamber calibration, and absolute field calibration [9][10][11][12]. In Rothacher et al [13], Seeber et al [14], and Mader [15], the relative field calibration method is introduced and described.…”

“…In addition to the above-mentioned two, the Geo++ GmbH calibration system is additionally operational at Geoscience Australia in Canberra, Australia [22], and Senatsverwaltung für Stadtentwicklung Berlin (SenB), Germany [19]. Furthermore, in addition to all of the above, there are five absolute calibration systems operational or under development worldwide: the National Geodetic Survey in the USA [23,24], GNSS Research Center of the Wuhan University in China [8,25], the Institute of Geodesy and Photogrammetry at ETH Zürich in Switzerland [10,11,16], Topcon Positioning System in Italy [26], and the Institute of Geodesy and Civil Engineering of the University of Warmia and Mazury in Poland [12]. According to the available literature, the Institute for Geodesy and Geoinformation of the University of Bonn in Germany is the only institution that has developed and operates antenna chamber calibration [17,27].…”

“…The constant parameter r, contained in Equation ( 4), is denoted as the datum parameter and is present due to the relative character of GNSS observations, i.e., because with GNSS, only one-way pseudo-ranges can be measured. This parameter does not affect the position estimates and is fully absorbed into the receiver clock error [9,12,39,47]. By analyzing Equation ( 4), it is evident that a set of PCC values can be transformed to any PCO vector and PCV set.…”

Offsets in the EPN station position time series resulting from antenna/radome changes: PCC type-dependent model analyses

“…However, despite their constant development, such systems still seem to be of little practical use. The GNSS antenna calibration technology development is also manifested through new calibration centers (Willi et al 2020;Wübbena et al 2019;Dawidowicz et al 2021) or the inclusion of new GNSS signals in the calibration process (Kröger et al 2021;Wanninger et al 2022).…”