Shipping traffic at sea channel of Port Rostock
The project is one of the initial projects of the Forschungshafen Rostock initiative (Research Port Rostock) geared towards the development and setup of Ground Based Augmentation Systems GBAS) to support navigation in port areas and has been sponsored by the State of Mecklenburg-West Pomerania. These systems are aimed at ensuring precise positioning in the sub-meter range while at the same time monitoring current performance.
Current state of research and technology
The development of differential positioning methods was accelerated by the civilian community of GPS users at the beginning of the 1990s in order to effectively reduce accuracy problems with single-frequency GPS positioning. At established measuring stations, errors with high spatial correlations such as
are identified and passed on to the users in the vicinity of the reference station as correction values. At the same time, IALA DGNSS networks were set up for maritime applications in order to reliably ensure accuracy to within 10 m in coastal areas, in compliance with the International Maritime Organisation's (IMO) requirements for GPS-based positioning systems.
Meanwhile, the performance requirements set by the IMO for GNSS-based localisation have risen. To ensure accuracy in the dm range while simultaneously monitoring integrity in port areas, augmentation systems are still required, though with more modern processes. According to initial studies by IALA (International Association of Marine Aids to Navigation and Lighthouse Authorities), augmentation systems suitable for this are those which use pseudolites or phase-based differential methods. This was one of the reasons for launching the SEA GATE (pseudolites) and ALEGRO (phase-based DGNSS/DGALILEO) projects as part of the research port initiative.
Localisation and navigation in the shipping industry and other transport sectors is classified as a safety-critical application of satellite-based navigation systems. A reliable self-assessment of the positioning accuracy that can currently be achieved is therefore necessary, taking into account all the technical and environmental factors. GALILEO is the first satellite system to systematically implement this integrity function, and consequently it must also be systematically developed and implemented for local augmentation systems.
To fulfil the safety requirements, users of GNSS/GBAS-based localisation systems must be informed within a few seconds in the event of system errors and signal interference that result in losses of accuracy greater than the permitted positioning error. The challenge this presents is to develop integrated system solutions that allow high-precision localisation coupled with integrity monitoring under all conditions. When the technology is able to ensure this comprehensively, it will mark the first steps on the road to automated berthing manoeuvres.
The primary goal of the project was to develop hardware and software for a phase-based GBAS (Ground Based Augmentation System) experimental system at the Port of Rostock. The experimental system was realised on the basis of EVnet technology, a universal platform for data acquisition, processing, and data product distribution. A key element in the GBAS processing system is the "GNSS Performance Assessment Facility" that derives signal-specific quality parameters from the incoming data streams of a receiver to provide a first real-time integrity monitoring of the GNSS used. Provision of measured values from the reference station to the users is decided on the basis of the usability of these values for DGNSS, which is inferred from the relationship between reference values measured in real time, station-specific reference values, and positioning with the DIA process (Detection, Identification, Adaption) at the established location. A mobile user platform was also developed and used for testing and validating the GBAS at the Port of Rostock The GBAS ground system and the mobile user platform are already prepared for processing GALILEO signals.
The ASMS (Advanced Sailing Management System) follow-up project, subcontracted by the Schiffahrtsinstitut Warnemünde (Warnemünde Shipping Institute), aims to augment the existing ALEGRO GBAS by setting up an independent integrity monitoring station.