UK and Ireland will discontinue the DGPS service in March 2022

[skeezix]

https://www.trinityhouse.co.uk/news/tri-gla-decision-to-discontinue-dgps-service-in-2022

The General Lighthouse Authorities of the UK and Ireland—Trinity House, the Northern Lighthouse Board and Irish Lights—will discontinue their Differential GPS (DGPS) service in March 2022. The GLAs made this decision after carefully considering the results from an extensive consultation carried out with stakeholders and service users. They will cease transmission of the signal after 31 March 2022.

The GLAs introduced DGPS in 1995 as part of the mix of marine aids to navigation (AtoN) provided to safeguard mariners within their combined waters and to help protect the environment. The system became fully operational in 1997.

The system consists of 14 DGPS reference stations, six far-field monitoring sites and three monitoring and control sites. The system is operated as a single AtoN, operated and maintained by the three GLAs.

Dr Alan Grant, GLA DGPS System Director, said:

“After careful consideration of the results of the consultation process, the three GLAs have concluded that their DGPS system is now redundant. Today’s GNSS are able to meet all but the most stringent accuracy requirements, and position integrity can be provided by alternative means (RAIM or other visual and electronic aids to navigation).

“The GLAs recognise the need to provide adequate notice and support continuity of service going forward. As such, the DGPS system will remain operational until 31 March 2022, at which point the signals will cease.”

BACKGROUND
Marine radiobeacon DGPS was developed by the GLAs to counter Selective Availability (SA), a deliberate error added to the civilian GPS service to degrade its positional accuracy. The DGPS correction to the position error meant an improvement in accuracy from approximately 50m to around 5m.

In addition to improving the estimated position accuracy, by assessing whether the error is within a given threshold, the reference station is able to monitor the performance of the GPS constellation and identify any faults. Faulty satellites are removed from the position solution, providing position integrity for the mariner.

SA was discontinued in 2000 and GPS now offers the civilian user a position accurate to around 3-5m. DGPS still improves positional accuracy—now enabling positions in the region of 1-2m—but it is the position integrity function that is most often cited as the main benefit of DGPS.

While marine radiobeacon DGPS is not mandated by the International Maritime Organization for carriage on SOLAS vessels, it is provided for in all maritime receiver standards and the spectrum is allocated internationally.

CONSULTATION
The infrastructure required to run the service is approaching the end of its design life; the GLAs conducted a stakeholder consultation to assess the requirements for the service going forward, surveying and interviewing stakeholders from across the maritime sector and beyond.

Of the responses received, 86% were from mariners and maritime operators, operating a wide range of vessels including ferries, container ships, tankers, liquid natural gas carriers, bulk carriers and leisure craft.

The survey resulted in a mix of responses, with the majority of mariners reporting that they use the DGPS system for accuracy improvements and integrity, while others reported that they do not use it.

All mariners reported using GPS today with around 40% also making use of GLONASS, and around 9% using Galileo too. From the response received, it is expected that more mariners will move to multi-constellation receivers, making use of GPS, GLONASS, Galileo and BeiDou over the next five to ten years.

MARITIME SAFETY
Following a change in maritime receiver standards in 2003, all receivers now include Receiver Autonomous Integrity Monitoring (RAIM). RAIM is a means of determining whether the resulting position estimate is safe to use through an algorithm within the receiver.

Differential corrections are also available from other sources, including Satellite Based Augmentation Systems (SBAS), which are primarily provided for aviation users. Work is under way in Europe to introduce a maritime service to EGNOS, the European SBAS. This service is expected to be available around 2022.

Vessels that need high accuracy position and integrity for operations mainly utilise a number of commercial satellite-based services; the decision to discontinue DGPS has no operational impact on these services.

The GLAs advise mariners to consider their use of DGPS and to plan for its discontinuance accordingly. Mariners should check their GNSS receiver(s) to confirm the presence of RAIM and consider upgrading to type-approved SBAS receiving equipment when available.

The GLAs encourage mariners to use all available AtoN - whether visual or electronic - to support their safe passage and the protection of the environment.

Download the full DGPS article by Dr Alan Grant [PDF]

[ChrisSmolinski]

That leaves Canada, Continental Europe and Panama/Brazil? The next winter may be my last serious DGPS DXing season.

[skeezix]

Yeah, not much left. Not that got many from UK/Ireland or elsewhere in Europe except on exceedingly rare occasions, but those have always been highly desired.

Haven't seen anything about Canada going away... yet.

[skeezix]

They've been discontinued.

https://www.nlb.org.uk/navigation/notices-to-mariners/
https://www.irishlights.ie/safety-navigation/notices-to-mariners/2022-03-reminder-of-discontinuation-of-dgps.aspx

Notices to Mariners Reminder of the discontinuation of Differential Global Positioning System (DGPS)
03 - 2022
Issue Date: 01 January 2022

Aid:

Area:

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

More information:
https://www.nlb.org.uk/wp-content/uploads/GLA-DGPS-Article-by-Dr-Alan-Grant-PDF.pdf