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More on eLoran

In spite of the successful development, favorable technical assessments, and a long standing presidential mandate for a GPS backup, in 2010, eLoran funding, and Loran-C transmissions in the U.S. and Canada were terminated. But recently, with the increasing awareness of the security threat posed by GPS denial, there has been a renewed interest in eLoran. The Howard Coble Coast Guard and Maritime Transportation Act of 2014 (H.R. 5769) directed the USCG to cease activities related to the dismantling or disposal of infrastructure that supported the former Loran-C sites, and further encourages “cooperative agreements, contracts, and other agreements with Federal entities and other public or private entities, including academic entities, to develop a positioning, timing, and navigation system, including an Enhanced Loran system, to provide redundant capability in the event GPS signals are disrupted.”

eLoran is an overlay on the internationally standardized Loran-C PNT service, and is “defined” as a PNT solution that includes transmissions synchronized to UTC, at least one Loran Data Channel (LDC), Additional Secondary Factor (ASF) mapping, and differential corrections. It is ideally suited to serve as a complement to GPS as its signal generation and transmission is quite different and completely independent of GPS.

Basic eLoran PNT performance starts off good, and improves with static and dynamic configuration data. During the implementation of a fully realized eLoran service, users can take advantage of interim capabilities. The cited eLoran accuracies below are in terms of 2DRMS, 95%.

Basic Initial Operational Capability (IOC)

Includes UTC synchronization, LDC, and rudimentary propagation delay corrections (ASF) based upon ITU conductivity maps and sophisticated ASF models.

  • Timing typically better than +/- 500 nanoseconds
  • Timing often better than +/- 100 nanoseconds after one-time calibration
  • Positioning typically less than 100 meters

Advanced Operational Capability (AOC)

Basic IOC eLoran plus modeled or surveyed ASF delay corrections

  • Timing typically better than +/- 100 nanoseconds
  • Positioning typically 50-100 meters, or less

Full Operational Capability (FOC)

AOC with differential delay corrections

  • Timing typically better than +/- 50 nanoseconds
  • Positioning typically better than ten meters (~ 33 feet)

eLoran is a mature technology, developed and refined in the U.S. Its development goals included low cost of ownership, very high reliability, and improved accuracy, availability, reliability, and continuity, as compared to Loran-C.

How Does UrsaNav Use eLoran?

UrsaNav is the world’s leading supplier of eLoran technology. We have developed comprehensive solutions for the General Lighthouse Authorities of the United Kingdom and Ireland (GLAs) which include a complete set of nine Differential Loran (Dloran) Reference Station sites and two Monitor and Control System (MCS) sites as part of an Initial Operating Capability (IOC) level Dloran System.

UrsaNav provided the world’s first combination DGNSS/eLoran “Resilient PNT Receiver” as part of the Accessibility for Shipping, Efficiency Advantages and Sustainability (ACCSEAS) project, a three-year effort supporting improved maritime access to the North Sea Region through minimizing navigation risk.

In addition UrsaNav has consulted with and made eLoran system design recommendations to many of the countries that are planning to implement eLoran systems including, The United States, Republic of Korea, India, Vietnam, and Kingdom of Saudi Arabia.