|Since March 15th, 1999, the U.S. Coast Guard Navigation Center has operated the Nationwide Differential GPS (DGPS) Service, currently consisting of one control center and 83 remote broadcast sites. The DGPS service broadcasts correction signals on marine radiobeacon frequencies to improve the accuracy and integrity to GPS-derived positions.
Users can expect better than 10-meter accuracy throughout all established coverage areas. Typically, the positional error of a DGPS position is 1 to 3 meters. In addition, this maritime service provides 10-meter (2 dRMS) navigation accuracy and integrity alarms for GPS and DGPS out-of-tolerance conditions within ten seconds of detection.
Proposed NDGPS Transition
DGPS is an all-weather GPS augmentation system.
Shown above is a DGPS reference station antenna.
|Over time, a number of factors have contributed to the declining public use of Nationwide Differential Global Positioning System (NDGPS), including lack of a carriage requirement, technological advances in GPS, and limited availability of consumer-grade DGPS receivers. In collaboration with the Department of Transportation and U.S. Army Corps of Engineers, the U.S. Coast Guard has finalized a Federal Register Notice (FRN) that reduces the number of Differential GPS sites throughout the country, while maintaining coverage in major maritime ports and waterways. The FRN and graphics depicting the changes to the system are accessible via the links below.
NDGPS provides service for coastal coverage of the continental U.S, the Great Lakes, Puerto Rico, portions of Alaska, Hawaii, and a greater part of the Mississippi River Basin. The plots attempt to account for ground conductivity, transmitter output power, and land topography using Millington’s method. To view these coverage areas, simply use the links below.
The US Coast Guard operates the Nationwide DGPS System for surface users. The primary users of this GPS augmentation system are mariners and surveyors. To provide this free service, the US Coast Guard leverages its partnerships with the US Department of Transportation (DOT) and the US Army Corps of Engineers.