Back to the future for LORAN

Malcolm Latarche
Malcolm Latarche

19 September 2018


In recognition of the potential problems with GPS some countries are re-introducing an improved LORAN system. Enhanced Long Range Navigation (eLORAN), is the next generation of LORAN and has a reported accuracy near that of conventional GPS positioning in coast-wise and harbor applications, and uses the infrastructure that is already in place.

Its effectiveness is a result of solid-state transmitters, advanced software applications and uninterruptible power sources, along with a new generation of shipboard receivers. Because the signal is much more powerful than GPS, eLORAN is not nearly as susceptible to jamming.

An eLORAN receiver gets its location information by measuring the arrival times of the pulses of at least three eLORAN stations. Using the measured timing values, the user is able to determine latitude and longitude of the receiver’s position, and its time with reference to universal time (UTC).

With conventional LORAN the absolute accuracy of the lattitude/longitude position is a function of effects to the signal passing over irregular terrain. These deviations from modelled propagation are known as Additional Secondary Factors (ASFs). By measuring and mapping the ASFs, and adjusting the measured arrival times accordingly, the user’s position accuracy of 20 to 50 metres can be achieved. By using Differential eLORAN techniques, the position accuracy can be further improved to the order of 10 metres.

In early 2013, The General Lighthouse Authorities of the UK and Ireland (GLA) announced that ships in the Port of Dover, its approaches and part of the Dover Strait can now use eLORAN technology as a backup to GPS. The ground based eLORAN system provides alternative position and timing signals for improved navigational safety.

The GLAs’ plan was to extend their current trials and to continue building a European consensus in favour of eLORAN and to prepare for the introduction of eLORAN services in 2018. However, it would appear that potential European partners are less keen and on the 31st of December, 2015, eight European LORAN stations in France, Norway, Denmark and Germany were decommissioned.

However, in the Netherlands, a local company Reelektronika has, on request of the Dutch Pilots Corporation, developed and successfully tested Enhanced Differential Loran (eDLoran). The company said in January 2014 an accuracy of 5 metres was achieved at sea and in the Rotterdam Europort harbour area. A complete test system has been implemented

Which includes the eDLoran reference station and the eDLoran receiver for the pilots. This small and lightweight receiver can link using wi-fi with the standard software of the pilot’s GPS-RTK equipment. New equipment for vessels using the system has been developed and released in 2017.

The US also has most of the infrastructure in place to initiate eLORAN without much delay and Russia and China also have LORAN systems that can be upgraded. The Russian system is commonly referred to as Chayka rather than LORAN but operates on the same principles. In December 2014, the US Department of Defense (DoD) decided to investigate future possibilities and in January 2015 invited tenders for possible supply of some 50,000 eLORAN receivers. The DoD is looking at both stand-alone eLORAN receivers and receivers that integrate eLORAN and GPS. More specifically they are looking for data on the size, weight, power, and cost of eLORAN receivers designed for maritime, aviation, vehicular, and timing applications.

In June 2015, a US Coast Guard Loran mast in Wildwood NJ was reactivated for a year-long demonstration and research eLORAN project. The signal is receivable at distances of up to 1,000 miles. As well as maritime uses, the US believes that eLORAN can provide navigation for drones in its airspace. The project involves two engineering companies, UrsaNav, a supplier of eLORAN technology, equipment, and services, and Harris (which recently acquired Exelis), provide funding and technology for the tests supported by the USCG, Department of Defense, Department of Homeland Security and other federal agencies under a Cooperative Research and Development Agreement.

Elsewhere, regular jamming of GPS signals by North Korea is alleged by the government in South Korea. In 2015 it was announced that this has prompted the South Korean government to implement an eLORAN system that will cover the entire country. The goal of the South Korean system is to provide better than 20-metre positioning and navigation accuracy over the country. The South Korean government hopes to expand coverage to the entire Northeast Asia in close collaboration with Russia and China in the near future. India and Saudia Arabia are also said to be interested in the technology.