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GNSS Augmentation Systems in the Maritime Sector

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GNSS Augmentation Systems in the Maritime Sector GNSS augmentation systems in the maritime sector Michael Fairbanks, The General Lighthouse Authorities of the UK and Ireland Nick Ward, The General Lighthouse Authorities of the UK and Ireland William Roberts, Nottingham Scientific Limited, UK Mark Dumville, Nottingham Scientific Limited, UK Vidal Ashkenazi, Nottingham Scientific Limited, UK BIOGRAPHY GNSS for aviation, maritime and rail applications. He has over ten years experience in transport and non-transport Dr Michael Fairbanks is currently working as a applications of GNSS technology, his main interests radionavigation specialist for the General Lighthouse relating to the technical and operational challenges facing Authorities of the UK and Ireland. He has many years the different user communities in their transition to experience of radionavigation policy and planning in the satellite navigation systems. maritime and aviation sectors in Europe and internationally. He has been involved in the European Professor Vidal Ashkenazi is the Chief-Executive Officer satellite navigation program since 1995 and was of NSL. Prior to establishing NSL, Professor Ashkenazi instrumental in establishing the European Maritime founded the Institute of Engineering Surveying and Space Radionavigation Forum (EMRF). Dr Fairbanks has Geodesy at Nottingham University which grew into one Bachelor and Doctorate degrees in Physics from Oxford of the leading satellite navigation institutes in Europe. University. He is a Fellow of the Royal Institute of Professor Ashkenazi is internationally recognized as a Navigation and a Member of the Institute of Navigation. leading authority on satellite navigation. He is a Fellow of He is also a Member of the Institute of Physics and a the Royal Academy of Engineering and is a member of Chartered Physicist. the editorial board of both GPS World and Galileo's World magazines. Dr Nick Ward is the Head of the GLAs Development Department with overall responsibility for all GLA ABSTRACT research and development activities. Dr Ward has a wealth of experience in the maritime radionavigation The provision of differential global positioning system sector and has, accordingly, held many positions of (DGPS) corrections, together with integrity information, responsibility, including the Chair (current) and secretary using non-directional medium frequency (MF) marine (previous) of the IALA Radionavigation Committee; the radiobeacons is well established and has proved Chair of the IALA Automatic Identification System (AIS) successful. However, the new signals to be available from Committee; UK observer on the NELS Steering GPS (L2C and L5) together with those transmitted from Committee; and Vice-President and Director of the Galileo (E5a and E5b) will undoubtedly impact on the International Loran Association (ILA) DGPS service, necessitating modification to enable augmentations to be provided for the new frequencies, as Dr William Roberts works as the Applications Manager well as that provided for the L1 signal. for Nottingham Scientific Limited (NSL). With Bachelor and Doctorate degrees in Surveying Science, he has over In addition, there are a number of emerging systems, such ten years commercial experience in the GNSS industry. In as space-based augmentation systems (SBAS), terrestrial 1992-3, Dr Roberts was instrumental in the development regional augmentation systems (RAS), on-board systems of the United Kingdom Offshore Operators Association and proposed Galileo services that will be available in the Guidelines for the Use of Differential GPS in Offshore near future. These new systems could either complement Surveying. These were the first industrial standards for or compete with the maritime DGPS service and may well describing the quality, in terms of precision and reliability provide additional capability to enable new applications. (or integrity), of GNSS positioning. Furthermore, maritime requirements have evolved Dr Mark Dumville is the General Manager of NSL. He is considerably since the design of the DGPS service. These currently working on projects relating to the use of the requirements not only cover general navigation by conventional craft but now also include high speed craft element of the WWRNS but, due to problems with (HSC), fast manoeuvrable craft (FMC) and the plethora of maintaining the constellation and the limited number of other applications that need position, velocity and time receivers available, GLONASS has not been as successful inputs. The current snapshot of these requirements has as GPS. been promulgated by the International Maritime Organization in Resolution A.915(22). However, these Despite delivering levels of performance unknown requirements will evolve as new applications develop and beforehand, GPS has a number of well-established system capabilities are enhanced. shortcomings including a lack of basic integrity and limited accuracy, especially in the presence of selective In response to these changes, the General Lighthouse availability which was not terminated until May 2000. Authorities (GLAs) of the UK and Ireland have launched Marine aids to navigation (AtoN) providers therefore a major study to support the development of future established a differential GPS service based on the radionavigation systems policy. The study has assessed broadcast of augmentation data using marine medium future performance of the global components of GNSS frequency (MF) radiobeacons. This standardised service (GPS, and Galileo) in the maritime context. The study is termed the IALA DGPS service is now operational in also assessing the contribution that can be made by the many of the most significant coastal waters throughout the various augmentation systems (regional, local and world and is available free-of-charge at the point of autonomous) to meet unfulfilled requirements and, delivery. therefore, enable additional applications. Concurrently, however, IMO has further developed The results generated to date suggest that, in order for the navigation requirements specific to a (future) global basic global requirement for general ocean, coastal and navigation satellite system (GNSS) and promulgated these port approach navigation to be met, a combined GPS- in an Assembly resolution [1]. In addition, carriage Galileo system will be required, operating on multiple requirements have been established, not only for an frequencies. Current augmentations, notably the IALA electronic position-fixing system based on DGPS system and the EGNOS service, will meet this radionavigation (satellite or terrestrial), but also for requirement but do not give the global coverage that is automatic identification systems (AIS) and voyage data needed. The more stringent requirements of port recorders (VDR) that rely on electronic position data as navigation and other operations, needing regional and input. There are a number of consequences to these local coverage, can only be met through local developments: augmentation systems and may require the current IALA DGPS system to be upgraded to operate on multiple (1) the reliance on GPS has increased, exacerbating the frequencies. The most stringent requirements for special consequences of a system failure based on its well- operations would then require implementation of carrier documented vulnerabilities and institutional phase systems which would have to be designed and constraints, without there being a realistic backup or located to support specific applications. alternative system to support GPS-based applications The utility of integrated inertial sensors will be (2) GPS will not meet the operational requirements of investigated as well as the capabilities of additional many current or new maritime applications. augmentation systems, such as Eurofix and the potential for using ranging signals from marine radiobeacons as This situation is not unique to the maritime sector and has well as LORAN-C stations. Future phases of the study resulted in technology development programmes, will then assess the opportunity to integrate maritime and including: non-maritime systems to enable mutual benefits, as well as determining the value, pros and cons of potential future (1) the development of space-based augmentation system mixes using cost-benefit and risk analysis in a systems (SBAS) in Europe (the European scenario driven methodology. Geostationary Navigation Overlay Service (EGNOS)), North America (the Wide Area INTRODUCTION Augmentation Service (WAAS)) and Japan (the multi-function transport satellite (MT-SAT)-based In 1996 GPS was offered by the United States to the Augmentation System (MSAS)), driven by the International Maritime Organisation as a contribution to aviation sector the World-Wide Radionavigation System (WWRNS). Subsequently, following recognition as such by IMO, (2) the development of a European core standalone GPS rapidly established itself as the principal radio-based system, called Galileo, similar to GPS under civil mechanism for position-fixing and navigation in the control and designed to meet multi-modal transport maritime sector. GLONASS was also recognized as an and other requirements by which to assess the performance of the potential core (3) integration of complementary systems, for example systems and their augmentations. It should be noted that GPS and inertial navigation systems and GPS and these requirements are forward-looking and much more LORAN-C, to increase the robustness and stringent than those currently in force. They should not, performance of the overall navigation solution.
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