RT Journal Article SR Electronic T1 Positioning with medium frequency R-Mode JF NAVIGATION: Journal of the Institute of Navigation JO NAVIGATION FD Institute of Navigation SP 829 OP 841 DO 10.1002/navi.450 VO 68 IS 4 A1 Grundhöfer, Lars A1 Rizzi, Filippo Giacomo A1 Gewies, Stefan A1 Hoppe, Michael A1 Bäckstedt, Jesper A1 Dziewicki, Marek A1 Del Galdo, Giovanni YR 2021 UL https://navi.ion.org/content/68/4/829.abstract AB R-Mode is a terrestrial navigation system under development for the maritime domain that provides backup in case of a GNSS outage. This paper describes the first test results for real-time positioning on board a ship using medium frequency R-Mode signals. The estimation and positioning algorithms used are described in detail and it is shown how they are integrated into the R-Mode receiver developed by the German Aerospace Center. Moreover, during two daytime experiments with lower and higher dynamic movements of a ship in the Baltic Sea, we were able to achieve a 95% horizontal positioning accuracy of better then 12 m in the center of three R-Mode transmitters. This demonstrates the first time that the medium frequency R-Mode has provided positioning at sea.