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**NOTICE**
The RTCM Special Committee 104 is suggesting retirement
of RTCM Message Types 4, 8, 11, 12, and 13. Any users
requiring these specific RTCM Message Types, please
contact DGPS System
Support by 1900Z November 15, 2009.
NAVCEN operates the Coast Guard Maritime Differential
GPS (DGPS) Service and the developing Nationwide DGPS
Service, consisting of two control centers and over 80
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.
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DGPS is an all-weather system
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| 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.
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