Support for LORAN TDs within Raymarine a/c/e/eS/gS-Series MFDs

[Chuck - Raymarine - Moderator]

Support for LORAN TDs within Raymarine a/c/e/eS/gS-Series MFDs

GPS Selective Availability (SA) ended a few minutes past midnight EDT after the end of May 1, 2000. The change occurred simultaneously across the entire satellite constellation. Given that GPS SA had ended and given the accuracy of Wide Area Augmentation System (WAAS) GPS receivers, Raymarine most other recreational marine electronics manufacturers ceased offering LORAN-C receivers in favor of WAAS GPS receivers. In recognition that many of its customers had acquired libraries of location data using LORAN-C Time Differences (TDs), Raymarine MFDs manufactured from 2003 through early 2011 (i.e. A/C/E-Series Classic MFDs, C/E-Series Widescreen MFDs, G-Series GPM400) included support for both LORAN-C TDs and Lat/Lon coordinates. Raymarine MFDs introduced from late 2011 to the date of this response (i.e. the a/c/e/eS/gS-Series MFDs) do not include support for support for LORAN-C TDs. A feature request has been logged to consider addition of support for LORAN-C TDs within a future a/c/e/eS/gS-Series MFD software update as well as within future MFD designs. However, there are computer based options to convert TDs to Lat/Lon coordinates. The Coast Guard Research and Development Center has developed POSAID2 ver 2.1a, a DOS-based program for converting LORAN-C time differences (TDs) to latitude and longitude. Another popular computer application for performing this one time conversion is SeaMarks by Andren. Andren also offers a data conversion service for those not inclined to purchase the SeaMarks computer application.

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Related LORAN-C information: LORAN-C was a ground-based navigation system operated by the U.S. Coast Guard. In May 2009, President Obama declared the system obsolete and announced plans to terminate it. In accordance with the 2010 DHS Appropriations Act, the U.S. Coast Guard terminated the transmission of all U.S. LORAN-C signals on 08 Feb 2010. A bill was reintroduced on September 9, 2016, as an element of the Coast Guard and Maritime Transportation Amendments Act of 2016. Section 106 of the bill, titled "Backup Global Positioning System", proposes that:

Subject to the availability of appropriations, the Commandant of the Coast Guard, in consultation with the Secretary of Transportation, shall provide for the establishment, sustainment, and operation of a reliable land-based enhanced LORAN, or eLORAN, positioning, navigation, and timing system to provide a complement to and backup for the Global Positioning System (in this section referred to as 'GPS') to ensure the availability of un-corrupted and non-degraded positioning, navigation, and timing signals for military and civilian users in the event that GPS signals are corrupted, degraded, unreliable, or otherwise unavailable.


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