AMSA discontinued its DGPS service on 1 July 2020 as it is no longer required to support safe navigation in Australian waters.  On 4 May 2020, we provided formal notification of the shut down of DGPS through Marine Notice 03/2020– Shut down of AMSA’s differential global positioning system (DGPS) service.

Your Global Positioning System (GPS) receiver will be unaffected by this action. 

How the discontinuation of DGPS will affect you

For the vast majority of maritime users, discontinuation of DGPS should not impact the accuracy of satellite positioning or the safety of navigation.
There will be no impact on Stand-alone GNSS.  However, GNSS receivers that have an integrated DGPS/DGNSS receiver, will no longer receive AMSA’s DGPS corrections and may alert or alarm.  This will be no different to what happens today as the receiver moves out of range of a DGPS stations.
The effects can be summarised as follows:

1. For GPS and DGPS capable receivers older than or fitted before 2003: 
   • If your receiver is DGPS enabled, the receiver will no longer receive AMSA’s DGPS signal.  It will continue to receive GPS information. This information is likely to be accurate to better than +/- 10 metres. 
   • Receivers that are older than or fitted before 2003 may not include an integrity monitoring capability. This means that they are unlikely to alert or alarm if integrity of the satellite signal is degraded.
   • If your GPS receiver is not DGPS enabled, then its performance will not change. For pre 2003 receivers, you should be aware that there is no integrity monitoring function built into your equipment. 
2. For GPS, GNSS or DGPS receivers newer than and fitted after 2003:
   • If your receiver is DGPS enabled, the receiver will no longer receive AMSA’s DGPS signal but will continue to receive GPS information. This information is likely to be accurate to better than +/- 10 metres.
   • Receivers newer than and fitted after 2003, will monitor the integrity of GPS information as received from GPS satellites. The receiver will alert or alarm if integrity of positional information is degraded.

What you should do if your GPS receiver is older than 2003

If your GPS receiver is older than or fitted before 2003, it might be time to upgrade your receiver.  It is unlikely that pre-2003 receivers will monitor the integrity of the information they receive. 

If integrity monitoring is important to you, then you may wish to replace your satellite navigation receiver with one that includes Receiver Autonomous Integrity Monitoring (RAIM). 

For higher accuracy, a multi-constellation GNSS receiver may provide better accuracy than a GPS-only receiver.

The Australian Satellite-Based Augmentation System project, led by Geoscience Australia, will deliver high accuracy positioning for GNSS users.  To benefit from this service in the future, you will need an ‘SBAS’ capable GNSS receiver. More information on the Australian SBAS project is available on the Geoscience Australia website.

Lastly, the better the receiver, the better the GNSS derived position will be. Just like a mobile phone, the technology for GNSS antennae and receivers has modernised significantly over the last 20 years.  Upgrading to a modern GNSS receiver is likely to provide improved precision and accuracy of the derived position. 

More information about the GPS Standard Positioning Service is available at:

• GPS.gov: Official U.S. government information about the Global Positioning System (GPS) and related topics
• An analysis of Global Positioning System (GPS) Standard Positioning Service (SPS) performance for 2017, March 20, 2018, Space and Geophysics Laboratory, Applied Research Laboratories, The University of Texas at Austin.
• Discontinuance of the Nationwide Differential Global Positioning System (NDGPS); A notice by the Coast Guard on 03/21/2018, on the National Archives Federal Register.  
• NDGPS General information; Navigation Centre, U.S. Department of Homeland Security.
• Trial of accurate positioning, Geoscience Australia.

Satellite-Based Augmentation System

Australia and New Zealand are working together to implement a Satellite-Based Augmentation System (SBAS). This technology will improve the accuracy of unaugmented GPS and other positioning services from the current five to 10 metres, to as little as 10 centimetres across our entire region.

This initiative follows 18 months of successful trials, which tested 27 projects across a range of industries.

Geoscience Australia and Land Information New Zealand will jointly deliver the capability. More information about SBAS is available on the Geoscience Australia website.