eLoran in the UK: Leading the Way

P. Williams, C. Hargreaves, D. Last, N. Ward

Abstract:	The General Lighthouse Authorities of the United Kingdom and Ireland (GLA) provide marine aids-to-navigation (AtoNs) for the benefit and safety of all mariners within their waters. These AtoNs include traditional lighthouses, buoys and various radionavigation systems. Visual signalling by lights and buoys has for centuries played a crucial role in marine navigation close to danger. Its role remains vital in the future world of e-Navigation, a concept driven by the International Maritime Organisation (IMO) to harmonise, integrate and exchange maritime information, to enhance berth-to-berth navigation. However, GNSS (effectively GPS) has become the primary Aid-to-Navigation (AtoN) used by all professional and most other mariners. The vulnerability of GNSS to space weather and interference (unintentional and criminal jamming) means that a backup system is needed to achieve resilient Position Navigation and Timing (PNT) for e-Navigation. Though the probability of losing GNSS may be low, the consequential impact could be very high and maintaining an appropriate balance of physical and radionavigation AtoNs is vital for e-Navigation. Enhanced Loran (eLoran) is the latest in the longstanding and proven series of low frequency, LOng-RAnge Navigation systems. eLoran evolved from Loran-C in response to the 2001 Volpe Report on GPS vulnerability. It vastly improves upon previous Loran systems with updated equipment, signals, and operating procedures. The improvements allow eLoran to provide better performance and additional services when compared to Loran-C. In recent years the GLA have been pioneering the introduction of eLoran in Europe. eLoran is an independent, dissimilar and complementary backup to GNSS and is the only credible and cost-effective option that, in the time available, can deliver e-Navigation’s urgently needed benefits of safety and security at sea and protection of the marine environment through the provision of resilient PNT information, taking over seamlessly when GNSS fails. The GLA have deployed a new eLoran transmitter station at Anthorn in Northwest England; conducted successful GPS jamming and eLoran trials; and continues to work with International colleagues to promote eLoran’s maritime and non-maritime benefits. The GLA’s eLoran strategy is to extend their current trials; to continue building a European consensus in favour of eLoran; and to move towards UK eLoran Initial Operating Capability (IOC) in limited UK waters by mid-2014. Loran IOC will comprise Port Approach accuracy (10m 95%) level eLoran at several major ports on the east coast of the United Kingdom. This will include one upgrade of the already existing prototype service at Harwich/Felixstowe and up to six new installations; Dover, the Thames Estuary to Tilbury, Humber (Immingham and Hull), Middlesbrough, Firth of Forth (to Grangemouth) and Aberdeen. The work of installing IOC level eLoran includes performing surveys of Additional Secondary Factor (ASF) data within each desired coverage area and the installation of a Differential-Loran (DLoran) Reference Station in the locality of each port. DLoran corrections will be broadcast using the Loran Data Channel – employing the Eurofix modulation scheme – implemented on the UK eLoran transmitter at Anthorn. IOC will also include a DLoran Reference Station Monitoring and Control Centre based in Harwich. As of the time of writing a European tender process has almost been completed for the Operational Level DLoran Reference Stations and Monitoring/Control Station. IOC eLoran will provide areas for demonstrations and trials so that mariners can gain experience in using the service and allow them to understand the benefits that eLoran can bring to the resilience and integrity of their operations. It is the aim of the GLA to complete IOC installation by the end of 2014. This paper describes the work done by the GLA in installing IOC level eLoran at the Port of Dover and the northern part of the Traffic Separation Scheme (TSS) within the Dover Strait; a vital sea traffic pinch point allowing access to and egress from the North Sea Region via the English Channel. Technical background is presented on the technology required for implementing eLoran in and around port approach areas. The overall architecture of the IOC level DLoran system is presented. We then focus on the implementation of eLoran in the Port of Dover approaches and the northern part of the Dover Strait TSS. The planning and performance of the Dover ASF survey is highlighted. Accuracy of the eLoran implementation is assessed through validation runs using a vessel passing through the region covered by the ASF map and served by the Dover DLoran reference station. The processes outlined in this paper will be repeated at each of the other candidate eLoran IOC ports, and the results of ASF surveys in approaches to the River Thames and River Humber are also briefly discussed.
Published in:	Proceedings of the ION 2013 Pacific PNT Meeting April 23 - 25, 2013 Marriott Waikiki Beach Resort & Spa Honolulu, Hawaii
Pages:	451 - 462
Cite this article:	Williams, P., Hargreaves, C., Last, D., Ward, N., "eLoran in the UK: Leading the Way," Proceedings of the ION 2013 Pacific PNT Meeting, Honolulu, Hawaii, April 2013, pp. 451-462.
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