Summary

  • Ofcom is retiring the UK licence for Differential Global Positioning System (DGPS) transmissions, a service the General Lighthouse Authorities stopped in 2022.
  • The regulator will continue protecting DGPS use around 300 kHz for the foreseeable future, because ships in UK, Irish and wider European waters may still receive signals from continental stations.

The British DGPS transmitter went quiet years ago. Its frequency, however, has not become a beach house for the next radio tenant. In its 23 October maritime spectrum decision, Ofcom does two things that sound contradictory only if a national licence is mistaken for the whole sea: it decommissions the DGPS licensing product and promises to keep protecting DGPS use from harmful interference.

The chronology matters. The General Lighthouse Authorities operated the UK's DGPS system from 1997 to 2022. It supplied corrections to satellite positioning at a time when ordinary GPS could miss by tens of metres. Trinity House warned mariners in January 2022 that the service would cease on 31 March. Receivers could show a lost-signal alarm, but would still deliver a GPS-derived position. The domestic service ended; Ofcom's dedicated licensing form then outlived the thing it authorised.

A consultation response supplied the missing geography. The General Lighthouse Authorities told Ofcom they supported retiring the licence, yet asked for continued protection around 300 kHz. Their reason was practical: vessels in UK, Irish and broader European waters can still use DGPS signals arriving from the continent. A radio boundary follows propagation and equipment, not the edge of an administrative form. Ofcom accepted that distinction. Its final statement says it currently has no plans to authorise other users on these frequencies and will protect DGPS use for the foreseeable future.

The licence exit is also being handled as an exit, rather than a midnight switch thrown against existing holders. Ofcom says those licensees have agreed to surrender their permissions. Separate authorisations are being developed for experiments and testing; a party seeking a trial would use the Innovation and Trial route. The public docket records the final statement and the lighthouse authorities' response. Neither document supplies a date on which the protected band will be offered to ordinary new users, or a list of continental stations on which particular ships rely.

The joke is that the supposedly empty filing cabinet still has a guard at the door. That guard protects a live cross-border use, while the old UK service and its bespoke licence leave the books. Spectrum governance sometimes has to retire its paperwork without pretending that radio waves received at sea have retired with it.

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