Increasing safety in inland waterway navigation with R-Mode

Kurzfassung

The electronic navigation equipment of modern vessels depends strongly on the position, navigation and timing information (PNT) obtained from global navigation satellite systems (GNSS). This dependency constitutes a single point of failure that can endanger the crew, passengers, environment and transported goods. The increasing threats to GNSS, like jamming and spoofing, motivates the adoption of alternatives sources of navigational information. R-Mode is an alternative PNT system which provides services similar to GNSS by using existing terrestrial radio infrastructure allowing the users to obtain a GNSS-independent position. In Germany the inland shipping sector contributes already significantly to the overall transport of goods but the inland waterways have the potential to increase it further to help Germany to meet its goal to reduce the greenhouse emissions of the transport sector. Within the framework of the German national project DigitalSOW, which aimed at the digitalization of the German inland waterways navigation and transportation to support autonomous transportation of goods, the medium frequency (MF) R-Mode, which was developed for the maritime domain, should also be made usable for inland waterways. Therefore, a medium frequency (MF) R-Mode transmitter was setup in Mauken and a differential element at the lock in Wernsdorf. This setup enabled in deep analysis of the R-Mode ranging performance for inland applications and the validation of the D(ifferential)R-Mode technique and new advanced concepts to increase the R-Mode system accuracy and reliability. The DR-Mode technique, that compensates mainly for transmitter errors, was demonstrated in the field showing that an increased ranging accuracy of about 54% can be achieved when corrections derived from the DR-Mode station are used. Moreover, a new approach to detect GNSS outages was proposed. The technique combines the expected positioning accuracy of a GNSS receiver, the R-Mode ranges and their associated expected accuracy and finally the geometrical relationship existing between the GNSS solution and the known location of the R-Mode transmitter. To validate the concept, real measurements recorded during a measurement campaign were synthetically modified, in post processing, to introduce two separate instances of simulated GNSS spoofing. During these events the GNSS positioning solution was characterized by an offset of approximately 100 m. The technique was then used to detect the spoofing events and rise a warning. It was shown that the method was able to detect the specific spoofing scenario. Therefore, the introduce approach can increase the resilience of PNT information on inland waterways.