ABSTRACT
A Positioning, Navigation and Timing (PNT) service using enhanced Loran (eLoran) has been transmitted experimentally in the United Kingdom for more than 5 years. The eLoran transmitter employed, at Anthom in North-West England, is operated by a commercial company on behalf of the General Lighthouse Authorities of the United Kingdom and Ireland. It is funded in part by the Department for Transport and other UK government agencies. Chronos Technology has used these and other eLoran transmissions to conduct research into the viability of employing eLoran as a means of distributing time traceable to UTC, including for indoor applications [1], There is growing interest internationally concerning the vulnerability of GPS and other global navigation satellite systems (GNSS) to natural and man-made interference, plus the jamming and spoofing of their transmissions. These vulnerabilities have led to a demand for sources of resilient PNT, including a robust means of distributing precise time nationally and internationally. This paper explores the ability of eLoran to disseminate UTC-traceable time to applications in GNSS-denied environments. It proposes the creation of a National Timescale with UTC distributed via eLoran signals. Practical results from a test programme are very encouraging: UTC-traceable time signals with an accuracy of better than 100 ns and with a quality comparable to that provided by GPS are received even indoors. This novel source of precise time meets the latest ITU standards for primary reference timing clocks in Internet Protocol networks.
