AMSA shuts down DGPS service

AMSA will shut down its radiobeacon differential global positioning system (DGPS) service from July 1.

AMSA established its radiobeacon DGPS service in the 1990s, to improve the accuracy and integrity of global positioning system (GPS) information for ships navigating off the coast of Australia.

At the time, the publicly available GPS signal was intentionally degraded, resulting in large position errors of up to 200 metres. 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 in harbour/harbour-approach navigation.

For the vast majority of maritime users, the discontinuation of AMSA’s DGPS service will not impact the accuracy of satellite positioning or safe navigation. DGPS receivers will no longer receive the AMSA radiobeacon 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.