Characteristics of Carrier Phase Measurements of an Inner Antenna in a Vehicle for RTK-GPS

Teppei Sekizawa, Taro Kashiwayanagi, Tetsushi Yamada, Katsuo Yui and Mikio Nakamura

Abstract:	RTK-GPS applications have been expected to be applied to various applications, especially for car navigation, while high performance GPS receivers using dual frequency measurements will be available for a reasonable price due to GPS modernization. As for RTK-GPS applied to car navigation, the antenna should be placed on a dashboard; however, the influence of glasses such as the windshield on the positioning accuracy is unavoidable. The accuracy is deteriorated due to carrier phase lags and depression of signal intensity caused by the glass refraction and reflection. Nevertheless, the deteriorating factor due to the windshield is scarcely investigated; almost no reports are found about carrier phase deviation of an inner antenna. We evaluated the influences of a windshield in carrier phase measurements by comparing experimental data of an antenna placed on the dashboard (hereunder referred to as dashboard antenna) and an antenna placed on the roof (hereunder referred to as roof antenna). Our evaluation shows that RTK-GPS positioning accuracy with the dashboard antenna was deteriorated, compared with the accuracy with the roof antenna. We investigated the two main factors supposedly deteriorating the phase measurements received by the dashboard antenna: multiple reflections of a windshield and multipath from the interior of the vehicle. Our investigation yields useful results for developing an anti-multipath system for RTK positioning in the case that the antenna is placed inside the vehicle like the dashboard antenna, particularly in optimizing signal processing for RTK-GPS applications.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	2210 - 2215
Cite this article:	Sekizawa, Teppei, Kashiwayanagi, Taro, Yamada, Tetsushi, Yui, Katsuo, Nakamura, Mikio, "Characteristics of Carrier Phase Measurements of an Inner Antenna in a Vehicle for RTK-GPS," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 2210-2215.
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