eLoran


Despite the closure of the the Loran-C chain in the USA, eLoran is alive and well in other parts of the world.

From Locus Inc. "Because GPS is vulnerable to intentional, unintentional, and natural interference, the US government is placing increased emphasis on technologies that can lessen the overdependence on GPS. While GPS technology is satellite-based and very high frequency, Loran uses ground-based transmitters and is low frequency. Loran signals are very high-powered, so they penetrate cities, buildings and densely foliaged areas where low level GPS signals are often blocked. From a practical perspective, Loran is virtually unjammable because of its high power.

Enhanced Loran or eLoran is a Loran system that incorporates the latest receiver, antenna, and transmission system technology to enable Loran to serve as a back-up to, and complement global navigation satellite systems (GNSS) for navigation and timing. This new technology provides substantially enhanced performance beyond what was possible with Loran-C, eLoranís predecessor.

For example, it is now possible to obtain absolute accuracies of 8-20 meters using eLoran for harbor entrance and approach. Similarly, eLoran can function as an independent, highly accurate source of Universal Time Coordinated (UTC). eLoran transmission infrastructure is now being installed (2004) in the US, and a variation of eLoran is now operational in northwest Europe. It is expected that there will be a global evolution towards eLoran, and users can anticipate integrated eLoran/GNSS receivers in the near future for a variety of applications".

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Separately from the above, Wouter Pelgrum writes. " I have recently defended my Ph.D. dissertation "New Potential of Low-Frequency Radionavigation in the 21st Century". This dissertation depicts the new possibilities of eLoran both by discussing the theory as well as by detailing measurement campaigns. In the last couple of years I have been involved with the development of a high-end eLoran receiver and antenna. With this new equipment we have demonstrated positioning accuracies of better than 10 meters, with 95% repeatability during a realistic harbor entrance and approach scenario. This performance is sufficient for the usage as a backup for GNSS for high demanding applications".

For anyone who is interested in these new developments, the dissertation is available online at: http://www.pelgrum.org/radionavigation

United Kingdom eLORAN Implementation

On 31 May 2007, the UK Department for Transport (DfT), via the General Lighthouse Authorities (GLA), awarded a 15-year contract to provide a state-of-the-art enhanced LORAN (eLORAN) service to improve the safety of mariners in the UK and Western Europe. The service contract will operate in two phases, with development work and further focus for European agreement on eLORAN service provision from 2007 through 2010, and full operation of the eLORAN service from 2010 through 2022. The first eLORAN transmitter is situated at Anthorn transmitting station Cumbria, UK, and operated by VT Communications, which is part of the VT Group PLC



References and Credits:

1) Locus, Inc. of Madison, Wisc
2) Wouter Pelgrum <wouter(at)pelgrum.org>
3) Douglas Sim <doug.sim(at)btinternet.com>


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Sep 6/10