NAVTEX / WEFAX
We'll talk about two technologies that have been around for a long time...
Today, there are multiple methods of getting the same data, faster and in better condition.
But this is Amateur Radio and we're all about, “When all else fails...”
These are two more for your toolkit that you can call upon when you're out in the field, no cell service and no Internet.
NAVTEX
Navtex – Navigational Telex
Developed by the International Maritime Organization (IMO) to provide a low-cost, simple and automated means of disseminating alerts, navigation and weather data to ships at sea, generally within 200 nautical miles from shore.
Operates on medium frequency of 518kHz
Messages are transmitted using binary frequency shift keying (BFSK) and utilize forward error correction.
NAVTEX Message Format
● Messages being with ZCZC which indicates the end of a phasing signal
● Following that are 4 characters that indicate: Station identification
Message type
Message number
Message number
Navigational Areas1 North Atlantic 9 Arabia
2 East Atlantic 10 Australia
3 Mediterranean Sea 11 East Asia
4 West Atlantic 12 Western Pacific
5 Brazil 13 Russia
6 Argentina 14 New Zealand
7 South Africa 15 Chile
8 India 16 Peru
NAVTEX Message FormatIndicator Message Subject Indicator Message Subject
A Navigational warning J SATNAV
B Meteorological warning K Other navaid msgs
C Ice reports L Navigational warnings
D Search & Rescue T n/a
E Meteorological forecast V Notice to fisherman
F Pilot service message W Environmental
G AIS message X Special services
H LORAN message Y Special services
I n/a Z n/a
NAVTEX Stations
Area ID Station Operator Transmission times (UTC)
4 A Miami USA 00:00, 04:00, 08:00, 12:00, 16:00, 20:00
4 B Bermuda Harbour BER 00:10, 04:10, 08:10, 12:10, 16:10, 20:10
4 E Savannah USA 00:40, 04:40, 08:40, 12:40, 16:40, 20:40
4 F Boston USA 00:45, 04:45, 08:45, 12:45, 16:45, 20:45
4 G New Orleans USA 00:45, 04:45, 08:45, 12:45, 16:45, 20:45
4 H Curacao NLD 01:10, 05:10, 09:10, 13:10, 17:10, 21:10
4 N Portsmouth USA 01:30, 05:30, 09:30, 13:30, 17:30, 21:30
4 R Isabela (Puerto Rico)
USA 02:00, 06:00, 10:00, 14:00, 18:00, 22:00
NAVTEX Schedule
● Each station receives a 10-minute slot and repeats every 4 hours
● NAVTEX schedule is maintained by the NOAA● http://www.nws.noaa.gov/om/marine/navtex.htm
Excerpt:Miami A 0000, 0400, 0800, 1200, 1600, 2000
San Juan R 0250, 0650, 1050, 1450, 1850, 2250
New Orleans G 0100, 0500, 0900, 1300, 1700,
NAVTEX Receivers
● Dedicated receivers are available. They're often used by cruising boaters and mandatory on some vessels.
● For the casual use and similar to what we do with other digital modes in Amateur Radio, there are software packages which can be used to decode the NAVTEX signal.
NAVTEX Software
● SeaTTY● PC Navtex● Mscan Meteo● Yand
SeaTTY
Live Text appears here as it's decoded
Received messages are filed in date order
SeaTTY – Decoded Message
1 Expand Folder
2 Select Message
1 Expand Folder
3 Read saved message
NAVTEX MessageZCZC RE89POC/COMMAND DUTY OFFICER/-/FLEWEACEN NORFOLK VA/LOC:NORFOLK VA/
TEL: 757-444-7583/EMAIL:FWC-NORFOLK.CDO(AT)NAVY.MIL// RMKS/745 FZNT26 KNHC 261431 OFFN05 NAVTEX MARINE FCST NWS NATIONAL HURCN CENTER MIAMI FL
THE END OF THE WEEK. SAN JUAN ATLC WATERS
THIS AFTERNOON...E TO SE WINDS 10 KT. SEAS 4 FT. SCATTERED SHOWERS AND ISOLATED TSTMS.
TONIGHT...E TO SE WINDS 5 TO 10 KT. SEAS 4 FT. SCATTERED SHOWERS AND ISOLATED TSTMS.
TUE NIGHT...E WINDS 10 TO 15 KT. SEAS 3 TO 4 FT. WED...E WINDS 10 TO 15 KT. SEAS 3 TO 4 FT. WED NIGHT...E WINDS 10 TO 15 KT. SEAS 3 FT. THU...E WINDS 10 TO 15 KT. SEAS 3 FT. THU NIGHT...E WINDS 10 KT. SEAS 3 FT. FRI...E WINDS 10 TO 15 KT. SEAS 3 FT. FRI NIGHT...E WINDS 10 KT. SEAS 3 TO 4 FT.//
NNNN
1 Station ID: “R” - Puerto Rico
2 Message Type: “E”Meteorological Forecast
WEFAX
WEFAX goes by a number of names...WEFAX – Weather FAXHF FAXRadiofacsimileWeatherfax
Produced by the National Weather Service's Marine Forecast Office, it's a means of broadcasting graphic weather maps, forecasts, and other graphic images via HF radio.
First things first... this technology dates on back to around 1926, but has stood the test of time and still used today.
Again.. are there better ways to get to the data? Of course! Sat Phones and glob-al internet connectivity are no doubt quicker and provide enhanced image clarity.
But wefax is HF, it works when other means of Internet connectivity are unavail-able and it's free for your taking.
WEFAX
● Schedule: http://www.nws.noaa.gov/os/marine/rfax.pdf Schedule includes broadcast location, frequency and time
● Just like operating HF, you pick the frequency based on time of day, band conditions, likely propagation, etc.
● WEFAX is not the same as decoding weather satellite data.
WEFAX
● Software SEATTY
Meteo Fax
WXTOIMG
● All weather data available for internet download http://weather.noaa.gov/pub/fax/Amaster_index.html
WEFAX
1 Select HF-Fax Mode
2 Tune radio to frequency
WEFAX
Thank you
