Navigation Center Logo
Skip Navigation Home | DGPS Advisories | GPS Constellation Status | GPS Testing Notices | LNMs | Almanacs | Nav Rules | AIS | North American Ice Service | Contact Us | Search
Nationwide Differential GPS (NDGPS)
Primary Mission Areas:
Services & Reporting:
Maritime Information:
NDGPS GENERAL INFORMATION

Note: The Omaha DGPS beacon (298 KHz, Site ID 868) has been terminated as of 1500Z (1100EST) May 15, 2013. For further inquiries, please contact the Navigation Information Service (NIS) via our Contact Us page or via phone at 703-313-5900.

_________________________________________________________

NAVCEN operates the Coast Guard Maritime Differential GPS (DGPS) Service and the developing Nationwide DGPS Service, consisting of one control center and 85 remote broadcast sites. The Service broadcasts correction signals on marine radiobeacon frequencies to improve the accuracy and integrity to GPS-derived positions. The Coast Guard DGPS Service provides 10-meter accuracy in all established coverage areas.

Typically, the positional error of a DGPS position is 1 to 3 meters, greatly enhancing harbor entrance and approach navigation. The System 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. Many foreign nations are implementing standard DGPS services modeled after the U.S. Coast Guard's system to significantly enhance maritime safety in their critical waterways.


The Coast Guard's maritime Differential Global Positioning Service achieved Full Operational Capability (FOC) on 15 March 1999 as announced in the DOT press release. The maritime DGPS service provides 10 meter (2 dRMS) navigation accuracy, integrity alarms for GPS and DGPS out-of-tolerance conditions within 10 seconds of detection, availability of 99.7% per month, coastal coverage to the continental United States, the Great Lakes, Puerto Rico/US Virgin Islands, and selected portions of Alaska and Hawaii.

The achievement of FOC culminates a six-year effort to convert existing radiobeacon sites and construct new sites to transmit DGPS corrections. Several equipment upgrades were installed to improve system performance. During the procurement and installation phases of the system upgrades, the maritime DGPS service operated under Initial Operational Capability rules, where the signals provided accurate corrections with integrity to the maximum extent possible.