2008 REED’s East Coast Edition - Navigation
Currently, DGPS towers are being estab- tion (the NAD 83 and WGS 84 Coordinate
lished thoughout the U.S., not just along the Systems are essentially identical for naviga-
coasts, improving the accuracy of GPS navi- tional purposes). Positions obtained using
gation everywhere. An updated list of coastal DGPS should be referenced to the NAD 83
DGPS stations in the U.S. and Canada are coordinate system only. Beware that there
located in REED’s Nautical Almanac. are possible differences between the NAD-83
Most differential signals are transmitted Coordinate System and the NAD-27 System
by the U.S. and Canadian Coast Guard from used on some older and some Canadian
former radio-beacon sites (see the DGPS charts. In fact, when comparing lat/long pos-
Beacons Table below. These signals in the tions between the two systems, differences of
MF/LF band (285-325 kHz) must be received over a mile have been reported. Government
on equipment designed for this purpose, and charts indicate the coordinate system being
the GPS receiver must be able to accept the used, and your GPS unit should be adjusted
corrections. DGPS improves positional ac- accordingly. See p. 846 for more information
curacy to 3-5 meters as compared with 100 on chart datums.
meters or standard GPS. Current information concerning the status of
Note that differential corrections are based GPS and DGPS is available through radio sta-
on the NAD 83 position of the reference sta- tion WWV and the Coast Guard’s NAVCEN.
DGPS Beacons
Broadcast site FREQ. TRANS. RATE RANGE LAT./LONG.
NOVA SCOTIA
Fox Island 307 kHz 200bps 162 45 19N, 61 04W
Western Head 296 kHz 100 or 200bps – – 43 59.4N, 64 39.7W
NEW BRUNSWICK
Point Escuminac 319 kHz 200 bps 162 47 04N, 64 47W
Partridge Island 311 kHz 100 or 200 bps – – 45 14.2N, 66 03.2W
MAINE
Penobscot 290kHz 200bps 65M 44 27.1N, 68 46.3W
Brunswick 316 kHz 100 bps 115M 45 53.4N, 69 56.8W
NEW HAMPSHIRE
Portsmouth Harbor 288 kHz 100bps 100M 43 04.3N, 70 42.6W
MASSACHUSETTS
Acushnet 306 kHz 200 bps 240M 41 44.6N, 70 53.2W
Chatham 325 kHz 200bps 95M 41 40.3N, 69 57.0W
NEW YORK
Moriches 293 kHz 100bps 130M 40 47.4N, 72 44.7W
NEW JERSEY
Sandy Hook* 286 kHz 200 bps 100M 40 28.3N, 74 00.7W
DELAWARE
Reedy Point 309 kHz 200 bps 150M 39 33.7N, 75 34.2W
MARYLAND
Hagerstown 307 kHz 100 bps 250M 39 33.2N, 77 42.8W
VIRGINIA
Driver 289 kHz 100 bps 130M 36 57.5N, 76 33.4W
Alexandria 305 kHz 100 bps 35M 38 45.2N, 77 07.7W
Portsmouth* 313 kHz 100 bps 75M 36 52.9N, 76 21.7W
NORTH CAROLINA
New Bern 294 kHz 100 bps 140M 35 10.5N, 77 2.92W
SOUTH CAROLINA
Charleston 298 kHz 100bps 150M 32 45.5N, 79 50.6W
GEORGIA
Savannah 319 kHz 100bps 185M 32 8.4N, 81 42.0W
844