NOAA Weather Radio Coverage Maps

VHF Marine Band radios, protocol, radio communication theory, practical advice; AIS; DSC; MMSI; EPIRB.
jimh
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NOAA Weather Radio Coverage Maps

Postby jimh » Fri Mar 25, 2016 12:54 pm

Several years ago I wrote an article describing how to use NOAA Weather Radio broadcast transmissions as test signals for testing a VHF Marine Band radio receiver and antenna. The article included or linked to several coverage maps provided by NOAA showing the expected coverage area of each of their transmitters and the expected signal levels.

The coverage map format has now changed, and the newer coverage maps now show a smaller general coverage area and do not show fringe reception areas. The change can be seen by comparison of an old and new coverage map for a particular station. I happen to have memorialized the old coverage map for station WXN69 in Sister Bay, Wisconsin, so it can provide the example:

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WXN69 coverage in old format. White is reliable coverage, green is fringe coverage.

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WXN69 coverage in new format. Only the white or reliable coverage contour is shown.

NOAA maintains a webpage that has a good index to all their transmitter sites and coverage maps. From this index you can find distant NOAA stations for your area that will provide a suitable signal for testing. On the index page, the coverage map signal level is specified: areas shown in white represent locations in which the NOAA transmitter should produce a signal of level of greater than 18 dBuV or what is deemed to be reliable coverage. The outer edge of the white coverage area is a predicted signal strength of 18 dbuV.

A signal level of 18 dBuV is equivalent to -89 dBm, or 18 dB more power than minimum sensitivity of -107 dBm. A signal of that strength should be very solid, clear, and noise-free copy on your receiver. For weaker signal testing, use a transmitter location whose coverage area in white does not include your location. Your receiver location should be beyond the white coverage area by a distance of perhaps 25-percent greater in order to provide a weaker test signal, around the 1-uVolt level, for receiver testing.

Also note that the listings of stations for each state in a table is provided by state-based index pages. The transmitter power is shown in those tables. Transmitter power of NOAA weather broadcast stations varies from 1,000-Watts to as little as 200-Watts.