Notices to Mariners

Reminder of the discontinuation of Differential Global Positioning System (DGPS)

03 - 2022

Issue Date: Saturday 1 January 2022

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The Commissioners of Irish Lights wishes to remind mariners of the contents of previously issued Notice to Mariners 04-2020. After careful consideration of the results of a comprehensive user consultation process, the General Lighthouse Authorities for the UK and Ireland have concluded that their Differential Global Positioning System (DGPS) is no longer required and have made the decision that the system will be discontinued from 31 March 2022.
The (DGPS) Service for UK and Ireland was established at a time when the publicly available GPS signal was intentionally degraded, resulting in large position errors. Augmentation was necessary to correct for these errors and meet minimum requirements for maritime positioning and navigation. In the year 2000, the intentional error in GPS positioning was removed. Since then, system technology has improved and the GPS constellation has been modernised. Observed positional accuracy for unaugmented GPS now consistently meets IMO requirements for accuracy around the coast of the UK and Ireland for marine navigation.
How will the discontinuation impact you?
For the vast majority of maritime users, the discontinuation of DGPS service for the UK and Ireland will not impact the accuracy of satellite positioning. DGPS receivers will no longer receive the DGPS signal in areas where it was previously available. This may generate a ‘lost signal’ alarm, but your receiver will still provide a GPS derived position.
Alternate sources for high accuracy positioning
Other options are available for obtaining higher accuracy positioning in the UK and Ireland.
Notice to Mariners No. 03 (2022) Page 2 of 2
Radio Navigation Warnings will be issued when the above changes take place.

By Order, Yvonne Shields O’Connor Chief Executive