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Nationwide Differential GPS (NDGPS)
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Maritime Information

The U.S. Coast Guard DGPS service is available for positioning and navigation. Users may experience service interruptions without advance notice. U.S. Coast guard DGPS broadcasts should not be used under any circumstances where a sudden system failure or inaccuracy could constitute a safety hazard. Differential corrections are based on the NAD83 (2011) position of the reference station (REFSTA) antenna. Positions obtained using DGPS should be referenced to NAD 83 coordinate system only. All sites are broadcasting RTCM Type 9-3 correction messages.


1. The DGPS beacon (290 KHz, Site ID 877) is unusable as of 1900Z December 21, 2014 until further notice. Impacts to the DGPS beacon service in Hawaii can be viewed here (clicking on the link will open a new browser window).

2. The Omaha DGPS beacon (298 KHz, Site ID 868) terminated at 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.

Please report DGPS problems or outages at our report-a-problem page. Thank you in advance.

Use the pull-down menu below to select the site in which you are interested. Outages, if any, will be shown below the site parameters after you select the site in which you interested.