NOTE: This Enhanced Loran (eLORAN) Definition Document has been drafted by the eLORAN Workgroup that was formed during the last Global AUgmentation of Satellite Systems (GAUSS) working session held at the 35th Annual Meeting of the International Loran Association (ILA www.loran.org) in Oct 2006. The purpose of the document is to provide a high-level definition of eLORAN for policy makers, service providers, and users. It was developed in November 2006 at the United States Coast Guard Navigation Center by an international team of authors.

Overview: Enhanced Loran is an internationally standardized positioning, navigation, and timing (PNT) service for use by many modes of transport and other applications. It is the latest in the long-standing and proven series of low-frequency, LOng-RAnge Navigation (LORAN) systems and takes full advantage of 21st century technology.

eLORAN meets the accuracy, availability, integrity and continuity performance requirements for aviation non-precision instrument approaches, maritime harbor entrance and approach maneuvers, land-mobile vehicle navigation and location-based services, and is a precise source of time and frequency for applications such as telecommunications.

eLORAN is an independent, dissimilar, complement to Global Navigation Satellite Systems (GNSS). It allows GNSS users to retain the safety, security and economic benefits of GNSS, even when their satellite services are disrupted.

Background: The predecessor of eLORAN, Loran-C, delivered a positioning accuracy of 460m, principally to mariners sailing in coastal and oceanic waters. When the Global Positioning System (GPS) appeared in the1980s, with its positioning accuracy of tens of meters, many began to regard Loran-C as irrelevant. But others saw it as an essential source of position and time that could still be relied upon if GPS failed.

The US modernization program resulted in this new version of Loran with significantly improved performance. It has much better accuracy, integrity and continuity while continuing to meet Loran-C’s traditional availability requirements. This improvement is realized through the addition of a data channel. This data channel allows eLORAN to meet the very demanding requirements of landing aircraft using so-called non-precision instrument approaches, and bringing ships safely into harbor in low-visibility conditions. eLORAN was also shown to be capable of providing the exceedingly precise time and frequency references needed by the telecommunications systems that carry voice and internet communications.

As eLORAN uses high-powered transmitters and low-frequency signals (not microwatts and microwaves like GNSS), it is very unlikely to be disrupted or jammed by the same causes that would disrupt GNSS signals. This means that small, low-cost, eLORAN receivers, even built into GNSS units, can mitigate the impact of disruptions to GNSS. Moreover, eLORAN can do things GNSS cannot, such as acting as a static compass. At sea, a new concept of navigation – enhanced navigation (e Navigation) – is being developed which requires an exceptionally reliable input of position, navigation and time data. Uniquely, the combination of GNSS and eLORAN has the potential to meet its needs.