MGBAS: RTK Service Validation and Service Integration Approach for a PNT Unit

Kurzfassung

The development of GNSS augmentation systems plays an important role for the use of satellite navigation in safety critical maritime applications, since they demand high accuracy and integrity (e.g. critical vessel operation areas like ports, restricted waterways or to support docking manoeuvres). A common augmentation technique used in the maritime sector is the IALA Beacon DGNSS (Differential Global Satellite Navigation System). Typically, this technique provides a horizontal accuracy of about 0.5m to 1m at the reference station and degrades typically about 0.4m to 1m for every 100nm of distance from the broadcast site [8]. But even if this technique helps to increase the accuracy and integrity of GNSS positioning, the performance is not sufficient to meet the IMO requirements for critical traffic areas like ports and automatic docking manoeuvres [10][11]. To achieve the required centimetre accuracy for such manoeuvres, an experimental “Maritime Ground Based Augmentation System (MGBAS)” has been implemented and developed since 2006 in the port of Rostock (Germany). The MGBAS comprises a reference station (RS) and an integrity monitoring station (IMS) operating as virtual user. Based on this concept GPS based Real- Time Kinematic (RTK) services with preliminary integrity monitoring are currently provided [16]. In order to satisfy simultaneously the system and user integrity the development of a MGBAS user segment as part of a PNT unit is envisaged for near future. On the one hand this paper presents the ongoing performance assessment of the MGBAS RTK services with respect to the IMO’s requirements. On the other hand it discusses the development of the MGBAS user segment as part of a PNT unit. Therefore, the beginning of the paper briefly introduces the existing MGBAS architecture ashore and motivates the necessity of an entire consideration of ashore services and on-board elements. In the second part the current RTK services are analysed over 15 days regarding their performance. Afterwards integrity monitoring modules at the IMS, whose application in the MGBAS user segment is intended, are briefly described regarding their functionalities and existing challenges. Finally, the paper concludes with an outline of the next steps in the development of the experimental MGBAS consisting of ashore and on-board components.