Nationwide Differential Global Positioning System (NDGPS)
The Nationwide Differential Global Positioning System (NDGPS) service augments GPS by providing increased accuracy and integrity using land-based reference stations to transmit correction messages over radiobeacon frequencies. The service was implemented through agreements between multiple Federal agencies including the United States Coast Guard (USCG), Department of Transportation (DOT), and United States Army Corps of Engineers (USACE), as well as several states and scientific organizations, all cooperating to provide the combined national DGPS utility. However, a number of factors have contributed to declining use of NDGPS and, based on an assessment by the Department of Homeland Security (DHS), DOT, and USACE, DHS, DOT, and USACE are proposing to shutdown and decommission 62 DGPS sites, which will leave 22 operational sites available to users in coastal areas. This notice seeks public comments on the shutdown and decommissioning of a total of 62 DGPS sites. Termination of the NDGPS broadcast at these sites is planned to occur on January 15, 2016.