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On the accuracy of absolute GNSS antenna calibration and the conception of a new Anechoic Chamber (2901)

Philipp Zeimetz and Heiner Kuhlmann (Germany)
Mr. Philipp Zeimetz
Institute of Geodesy and Geoinformation
University of Bonn
Institute of Geodesy and Geoinformation
Nu├čallee 17
Bonn
53115
Germany
 
Corresponding author Mr. Philipp Zeimetz (email: p.zeimetz[at]uni-bonn.de, tel.: +49228733565)
 

[ abstract ] [ handouts ] [ handouts ]

Published on the web 2008-03-21
Received 2008-01-31 / Accepted 2008-03-14
This paper is one of selection of papers published for the FIG Working Week 2008 in Stockholm, Sweden and has undergone the FIG Peer Review Process.

FIG Working Week 2008
ISBN 978-87-90907-67-9 ISSN 2307-4086
http://www.fig.net/resources/proceedings/fig_proceedings/fig2008/index.htm

Abstract

ABSTRACT The antenna effects are one of the accuracy limiting factors in relative GNSS positioning. They depend on the direction of the incoming satellite signal and are usually described by the phase centre offset (PCO) and the phase centre variations (PCV). Because these effects are essentially stable for unchanged antennas, it is possible to calibrate the antennas. Beside the relative and absolute field procedures there is an absolute laboratory procedure, which is ideally performed in anechoic chambers in order to avoid multipath effects. This paper presents some research on determining the accuracy of absolute calibration of GNSS-antennas in anechoic chambers. Because it is not possible to separate the near-field effects and the antenna effect, it is difficult to verify the accuracy of the calibration procedure. Based on the presented results, we found that the calibration accuracy at elevations above 10 degrees is mostly better than 1mm (maximal deviations) and still better than 2mm at lower elevations. The main part of the remaining deviations is caused by near-field variations. The disadvantage of the laboratory procedure is the low availability of suitable anechoic chambers. Now, a anechoic chamber is being constructed in cooperation between the Institute of Geodesy and Geoinformation of the University of Bonn and the Landesvermessungsamt NRW (surveying and mapping agency of North-Rhine Westphalia). In order to keep the project affordable the test range, the distance between transmitter and GNSS-antenna, was reduced as far as possible. One aspect of our research is the estimation of the effects which results from the reduced test ranges. The results show that the effects are negligible in our case. BIOGRAPHICAL NOTES Mr. Philipp Zeimetz holds a diploma degree in geodesy from the University of Bonn, Germany. He is a scientific assistant at the Institute of Geodesy and Geoinformation of the University of Bonn. His research is mainly focussed on the calibration of GPS-antennas. Prof. Dr. Heiner Kuhlmann is full professor at the Institute of Geodesy and Geoinformation of the University of Bonn. He has worked extensively in engineering surveying, measurement techniques and calibration of geodetic instruments.
 
Keywords: GNSS/GPS; Positioning; Engineering survey; antenna calibration; anechoic chamber; near-field; GNSS

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