ABSTRACT: The General Lighthouse Authorities (UK & Ireland) DGPS service came into operation in 1998. In common with other maritime DGPS services the equipment will need replacement over the next few years, in fact computing and communications equipment have already been replaced. Replacement of existing hardware with similar, dedicated Reference Stations and Integrity Monitors (RSIM) is the baseline option and will form a fallback plan if other options prove not to be feasible. However, the choice of suppliers is limited and once chosen, it would be difficult to diversify. Three other options can be identified: software RSIM, Virtual Reference Station (VRS) and integration with Satellite Based Augmentation Systems (SBAS). The software RSIM option draws on the experience of the United States Coast Guard. The VRS and SBAS integration options are treated as potential alternatives to an onsite hardware or software RSIM, but the possibilities of combining either or both with the software RSIM are also considered. All options took into account the need for validation of system performance. This paper draws conclusions about feasibility, performance, risks and costs of the different options and makes recommendations on the course to adopt.

KEYWORDS: Global Navigation Satellite System (GNSS), Satellite Based Augmentation System (SBAS), EGNOS, Reference Stations and Integrity Monitors (RSIM), Virtual Reference Station (VRS), Differential GPS (DGPS), Validation of System Performance, Differential GNSS (DGNSS)

REFERENCES