A response to the statement by Professor Martyn Thomas at the 2011 GNSS Interference, Detection and Monitoring Conference on Thursday 10 March.

The General Lighthouse Authorities of the UK and Ireland (GLAs) fully support the findings of the Royal Academy of Engineering’s paper on the dangers of heavy dependency on GPS, discussed today (10 March) by Professor Martyn Thomas at the 2011 GNSS Interference, Detection and Monitoring Conference.

Over the last few years, the GLAs have conducted two GPS jamming trials to investigate and demonstrate the effects of GPS failure on the maritime industry, which has an enormous reliance on GPS for positioning, navigation and timing information. The trials demonstrated that by jamming the GPS signal these units don’t simply stop providing information, but they provide erroneous data, some of which can be hazardously misleading. During both the GLAs jamming trials the vessel was reported to be travelling at unbelievable speeds and the reported position was many kilometres from the true position.

To mitigate this over-reliance on GPS, there is a need for resilient positioning, navigation and timing information and the GLAs have been working on a solution for almost a decade: the development of Enhanced Loran (eLoran).

eLoran is a complementary system to GPS, providing positioning, navigation and timing information that would enable ship systems to seamlessly continue their operation should GPS be affected.

eLoran is a low frequency (100 kHz) radio-navigation system using high-power, long-range transmitters. The pulsed signals provide accurate horizontal positioning for all modes of transport as well as timing for communications and other systems. Because of its properties, eLoran is an ideal complement to GPS and Global Navigation Satellite Systems (GNSS) in general. eLoran uses high-powered radio stations on earth, transmitting at low frequencies, to complement satellite navigation’s low-powered stations in space transmitting at high frequencies. One such radio station covers the UK and Ireland, part of a North West European system also involving France and Norway, a trial that we – the GLAs - are leading.

Two such different, complementary systems promise to maintain the highly-robust position, navigation and timing information we now rely on. The combination is stronger than the sum of its parts. Integration of eLoran into GNSS receivers can mitigate the vulnerability to jamming at minimal cost to the user. Industry is already producing integrated receivers.

Resolution of the major problem highlighted by Professor Martyn Thomas is close at hand, with the navigation authorities of UK and Ireland leading the world in this technology.

Notes to editors:

GPS Vulnerability

GPS signals are particularly weak and are susceptible to interference.  These weak satellite signals can be swamped by radio noise caused by solar storms, unintended man-made radio interference and even intentional jamming.  Regardless of the cause, the implications of losing GPS information can be dramatic and potentially severe.  

Modern vessels generally have several GPS receivers, providing navigation and timing information.  Increasingly these are integrated into equipment, meaning that should GPS fail, many of the vessel’s electronic systems are affected and cease to be available; all failing at once.

The General Lighthouse Authorities

The General Lighthouse Authorities (GLAs) of the United Kingdom and Ireland are Trinity House, the Northern Lighthouse Board and the Commissioners of Irish Lights. Together, they have the statutory responsibility for the provision of marine aids to navigation (AtoNs) around the British Isles. The GLAs’ joint mission is the delivery of a reliable, efficient and cost effective AtoN service for the benefit and safety of all mariners.

For more information please contact Vikki Gilson, Public Relations Manager for Trinity House, on 020 7481 6960 or email her at This e-mail address is being protected from spambots. You need JavaScript enabled to view it