Maritime Fax Transmissions
From HFUnderground
Radiofax, also known as weatherfax and HF fax (due to its common use in the short waves), is an analogue mode for transmitting images in grayscale. It is also related to slow-scan television (SSTV). The term weatherfax was coined after the technology that allows the transmission and reception of weather charts (surface analysis, forecasts, and others) from a transmission site (usually the meteorological office) to a remote site (where the actual users are).
Many of these products are used in conjunction with maritime weather transmissions in SSB voice (almost always USB mode) and RTTY.
Facsmile machines were used in the 1950s to transmit weather charts across the United States via land-lines first and then internationally via HF radio. Radio transmission of weather charts provides great flexibility to marine and aviation users, for they now have the latest weather information and forecasts at their disposal to use in the planning of voyages.
Radiofax relies on facsimile technology, where printed information is scanned line by line and encoded into an electrical signal which can then be transmitted over land-line or via radio waves to great distances. Since the amount of information transmitted per unit time is directly proportional to the bandwidth available, the speed at which a weather chart can be transmitted varies depending on the quality of the media used for transmission.
Today radiofax charts and images are available via FTP or HTTP downloads from sites in the Internet, such as the ones hosted by the National Oceanic and Atmospheric Administration (NOAA). Radiofax transmissions are also broadcast by NOAA from multiple sites in the USA at regular daily schedules. Radio weatherfax transmissions are particularly useful to shipping, where there are limited facilities for accessing the Internet. The German Meteorological Service (DWD) is another major producer of FAX charts, which are also transmitted on HF frequecies from a location near Kiel.
Contents |
Transmission details
Radiofax is transmitted in single sideband and uses frequency modulation. The signal shifts up or down a given amount to designate white or black pixels. A deviation less than that for a white or black pixel is taken to be a shade of grey. With correct tuning (1.9kHz below the carrier frequency for USB, above for LSB), the signal shares some characteristics with SSTV, with black at 1500Hz and peak white at 2300Hz. The official ITU radio emission designation is F1C. Note that some sources list this a "J1C". Some sources list the center frequency. In USB mode, the frequency is 1.9 kHz lower (dial frequency).
Usually, 120 lines per minute (LPM) are sent (For monochrome fax, possible values are: 60, 90, 100, 120, 180, 240. For colour fax, LPM can be: 120, 240).[1] A value known as the index of cooperation (IOC) must also be known to decode a radio fax transmission - this governs the image resolution, and derives from early radio fax machines which used drum readers, and is the product of the total line length and the number of lines per unit length (known sometimes as the factor of cooperation), divided by π (3.1416). Usually the IOC is 576.
Automatic Picture Transmission format (APT)
APT format permits unattended monitoring of services. It is employed by most terrestrial weather facsimile stations as well as geostationary weather satellites.
- The start tone triggers the receiving system. It was originally meant to allow enough time for the drum of mechanical systems to get up to speed. It consists of rapid modulation of the video carrier, resulting in a characteristic rasp-like sound.
- The phasing signal, consisting of a periodic pulse, synchronises the receiver so that the image will be centered on the paper.
- The stop tone, optionally followed by black, marks the end of the transmission.
| Signal | Duration | IOC576 | IOC288 | Remarks |
|---|---|---|---|---|
| Start tone | 5s | 300Hz | 675Hz | 200Hz for colour fax modes. |
| Phasing signal | 30s | White line interrupted by a black pulse. | ||
| Image | Variable | 1200 lines | 600 lines | At 120 lpm. |
| Stop tone | 5s | 450Hz | 450Hz | |
| Black | 10s |
Stations
Today, radiofax is primarily used worldwide for the dissemination of weather charts, satellite weather images, and forecasts to ships at sea. The oceans are covered by coastal stations in various countries.
In the United States, fax weather products are prepared by a number of offices, branches, and agencies within the National Weather Service (NWS) of the National Oceanic and Atmospheric Administration (NOAA).
- Tropical and hurricane products come from the Tropical Analysis and Forecast Branch, part of the Tropical Prediction Center/National Hurricane Center. They are broadcast over US Coast Guard communication stations NMG, in New Orleans, LA, and NMC, the Pacific master station on Point Reyes, CA. After Hurricane Katrina damaged NMG, the Boston Coast Guard station NMF added a limited schedule of tropical warning charts. NMG is back at full capability, but NMF continues to broadcast these.
- All other products come from the Ocean Prediction Center (OPC) of the National Weather Service (NWS), in cooperation with several other offices depending on the region and nature of information. These also use NMG, NMC, and NMF, plus Coast Guard station NOJ in Kodiak, Alaska, and Department of Defense station KVM70 in Hawaii.
- Ever since the RMS Titanic dramatized the dangers of icebergs in the North Atlantic, an International Ice Patrol has also originated weather data. Its charts are broadcast by the Boston Coast Guard station during the prime iceberg season of February through September, using the callsign NIK.
A major producer of Canadian radiofax is the Canadian Forces METOC (Meteorology and Oceanography Centre) in Halifax, NS, using the communication station CFH. Charts are sent on the hour, then the station switches to radioteletype (RTTY) for the rest of the period.
In Europe the most commonly received weather FAX service is the German Meteorological Service (Deutscher Wetterdienst or DWD), which transmits from Offenbach throught the day. The DWD frequencies and callsigns are:[4]
| Callsign | Frequency | Power |
|---|---|---|
| DDH3 | 3855.0 kHz | 10 kW |
| DDK3 | 7880.0 kHz | 20 kW |
| DDK6 | 13882.5 kHz | 20 kW |
CBV, Playa Ancha Radio in Valparaiso, Chile broadcasts a daily schedule of Armada de Chile weather fax for the southeastern Pacific, all the way to the Antarctic. Also in the Pacific, Japan has two stations, as does the Bureau of Meteorology in Australia. Most European countries have stations, as does Russia.
Kyodo News is the only remaining news agency to transmit news via radiofax. It broadcasts complete newspapers in Japanese and English, often at 60 lines per minute instead of the more normal 120 because of the greater complexity of written Japanese. A full day's news takes hours to transmit. Kyodo has a dedicated transmission to Pacific fishing fleets from Kagoshima Prefectural Fishery Radio, and a relay from 9VF, possibly still in Singapore. The frequencies formerly used by JJC radio outside Tokyo are now sent from an unknown location, using the same identification in Japanese as 9VF. They are still active and heard daily in 2010.
The Joint Operational Meteorology & Oceanography Centre, Nortwood, UK (callsign GYA) transmits various weather charts for the the Royal Navy on 2618.5 kHz, 4610.0 kHz, 6834.0 kHz, 8040.0 kHz, 11086.5 kHz, 12390.0 kHz and 18261.0 kHz. The charts cover North Atlantic, Europe and the Persian Gulf areas.
| Callsign | Frequency | Power | Program |
|---|---|---|---|
| GYA | 2618.5 kHz | 10 kW | Europe (2000-0600 UTC) |
| GYA | 4610.0 kHz | 10 kW | Europe (24h) |
| GYA | 6834.0 kHz | 10 kW | Persian Gulf (1800-0800 UTC) |
| GYA | 8040.0 kHz | 10 kW | Europe (24h) |
| GYA | 11886.5 kHz | 10 kW | Europe (0600-2000 UTC) |
| GYA | 12390.0 kHz | 10 kW | Persian Gulf (24h) |
| GYA | 18261.0 kHz | 10 kW | Persian Gulf (0800-1800 UTC) |
List of FAX transmissions
| (UTC) | Station | Callsign | Frequencies | Location | Comments |
|---|---|---|---|---|---|
| 0000 | Wiluna | VMW | 7535, 10555, 15615 kHz | AUSTRALIA | Weather FAX*; 120/576 |
| 0000 | USCG New Orleans, LA | NMG (NMG-2) | 4317.9, 8503.9, 12789.9 kHz | UNITED STATES - Atlantic and Gulf | Weather FAX*; 120/576 |
| 0000 | Charleville | VMC | 5100, 11030, 13920 kHz | AUSTRALIA | Weather FAX*; 120/576 |
| 0000 | Tokyo | JMH | 3622.5, 7795, 13988.5 kHz | JAPAN | Ice FAX; 120/576 |
| 0000 | Tokyo | JMH | 3622.5, 7795, 13988.5 kHz | JAPAN | Ice FAX; 120/576 |
| 0000 | Tokyo | JMH | 3622.5, 7795, 13988.5 kHz | JAPAN | Ice FAX; 120/576 |
| 0000 | Casey, AUS | VLM | 7470 kHz | ANTARCTICA | Weather FAX*; 120/576 |
| 0000 | Dakar | 6VA/6VU | 13667.5, 19750 kHz | SENEGAL | Weather FAX; 120/576 |
| 0000 | Tokyo | JMH | 3622.5, 7795, 13988.5 kHz | JAPAN | Weather FAX*; 120/576 |
| 0000 | USCG Boston, MA | NMF/NIK/NMF-7 | 6340.5, 9110 kHz | UNITED STATES - Atlantic and Gulf | Weather FAX*; 120/576 |
| 0000 | Honolulu, HI | KVM70 | 11090 kHz | UNITED STATES - Hawaii | Weather FAX*; 120/576 |
| 0000 | Halifax, N.S. | VCS/CFH | 122.5 MHz, 4271, 6496.4, 10536, 13510 kHz | CANADA - Arctic and Atlantic | Weather FAX*; 120/576 |
| 0000 | USCG Point Reyes, CA | NMC/NMC-17 | 8682, 12786, 17151.2 kHz | UNITED STATES - Pacific | Weather FAX*; 120/576 |
| 0001 | Halifax, N.S. | VCS/CFH | 122.5 MHz, 4271, 6496.4, 10536, 13510 kHz | CANADA - Arctic and Atlantic | Ice FAX*; 120/576 |
| 0010 | Iqaluit, N.T. | VFF | 3251.1, 7708.1 kHz | CANADA - Arctic and Atlantic | Ice FAX; 120/576 (Resolute) |
| 0130 | Tokyo | JMH | 3622.5, 7795, 13988.5 kHz | JAPAN | Ice FAX; 120/576 |
| 0140 | USCG Point Reyes, CA | NMC/NMC-17 | 4346 kHz | UNITED STATES - Pacific | Weather FAX*; 120/576 |
| 0200 | Inuvik, N.W.T. | VFA | 8457.8 kHz | CANADA - Arctic and Atlantic | Weather and ice FAX; 120/576 |
| 0230 | USCG Boston, MA | NMF/NIK/NMF-7 | 4235 kHz | UNITED STATES - Atlantic and Gulf | Weather FAX*; 120/576 |
| 0400 | Kodiak, AK | NOJ | 2054, 4298, 8459, 12412.5 kHz | Weather and ice FAX*; 120/576 | |
| 0430 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 7508, 13538 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 0430 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 4014 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 0430 | Offenbach/Pinneberg | DDH/DDK | 3855, 7880, 13882.5 kHz | GERMANY - North Sea | Weather FAX*; 120/576 |
| 0438 | USCG Boston, MA | NMF/NIK/NMF-7 | 4235, 6340.5, 9110 kHz | UNITED STATES - Atlantic and Gulf | Ice FAX; 120/576 (Feb. - Aug.) |
| 0500 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 4014 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 0500 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 7508, 13538 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 0500 | Iqaluit, N.T. | VFF | 3251.1, 7708.1 kHz | CANADA - Arctic and Atlantic | Ice FAX; 120/576 |
| 0519 | Honolulu, HI | KVM70 | 9982.5 kHz | UNITED STATES - Hawaii | Weather FAX*; 120/576 |
| 0530 | Pevek | 148 kHz | RUSSIA - Northern Coasts | Ice FAX, 90/576 | |
| 0600 | RN Northwood | GYA | 2618.5 kHz | UNITED KINGDOM | |
| 0630 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 18238 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 0630 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 7508, 13538 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 0655 | USCG Point Reyes, CA | NMC/NMC-17 | 4346 kHz | UNITED STATES - Pacific | Weather FAX*; 120/576 |
| 0700 | Iqaluit, N.T. | VFF | 3251.1, 7708.1 kHz | CANADA - Arctic and Atlantic | Ice FAX; 120/576 (Resolute) |
| 0700 | Murmansk | UDK/UDK2 | 6446, 7907, 8444 kHz | RUSSIA - Northern Coasts | Weather and ice FAX*; 120/576 |
| 0730 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 18238 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 0730 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 7508, 13538 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 0745 | Rio de Janeiro Naval | PWZ-33 | 12665, 16978 kHz | BRAZIL | Weather FAX; 120/576 |
| 0800 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 7508, 13538, 18238 kHz | SOUTH AFRICA | Ice FAX; 120/576 |
| 0800 | Murmansk | UDK/UDK2 | 6446, 7907, 8444 kHz | RUSSIA - Northern Coasts | Weather and ice FAX*; 120/576 |
| 0800 | RN Northwood | GYA | 6834 kHz | UNITED KINGDOM | |
| 0900 | Athens | SWA | 8106.9 kHz | GREECE | Weather FAX; 120/576 |
| 0900 | Charleville | VMC | 2628 kHz | AUSTRALIA | Weather FAX*; 120/576 |
| 0930 | Offenbach/Pinneberg | DDH/DDK | 3855, 7880, 13882.5 kHz | GERMANY - North Sea | Ice FAX*; 120/576 |
| 0950 | Kodiak, AK | NOJ | 2054, 4298, 8459, 12412.5 kHz | Weather and ice FAX*; 120/576 | |
| 1000 | Iqaluit, N.T. | VFF | 3251.1, 7708.1 kHz | CANADA - Arctic and Atlantic | Weather FAX; 120/576 |
| 1007 | Offenbach/Pinneberg | DDH/DDK | 3855, 7880, 13882.5 kHz | GERMANY - North Sea | Ice FAX*; 120/576 |
| 1019 | Tokyo | JMH | 3622.5, 7795, 13988.5 kHz | JAPAN | Ice FAX; 120/576 |
| 1030 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 18238 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 1030 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 7508, 13538 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 1100 | Iqaluit, N.T. | VFF | 3251.1, 7708.1 kHz | CANADA - Arctic and Atlantic | Weather FAX; 120/576 (Resolute) |
| 1100 | Wiluna | VMW | 5755 kHz | AUSTRALIA | Weather FAX*; 120/576 |
| 1100 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 18238 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 1100 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 7508, 13538 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 1115 | Valparaiso Playa Ancha | CBV | 4228, 8677, 17146.4 kHz | CHILE | Weather FAX; 120/576 |
| 1120 | USCG Point Reyes, CA | NMC/NMC-17 | 4346 kHz | UNITED STATES - Pacific | Weather FAX*; 120/576 |
| 1121 | Sydney, N.S. | VCO | 6915.1 kHz | CANADA - Arctic and Atlantic | Ice FAX; 120/576 |
| 1130 | Valparaiso Playa Ancha | CBV | 4228, 8677, 17146.4 kHz | CHILE | Weather FAX; 120/576 |
| 1130 | Pevek | 148 kHz | RUSSIA - Northern Coasts | Ice FAX, 90/576 | |
| 1142 | Sydney, N.S. | VCO | 6915.1 kHz | CANADA - Arctic and Atlantic | Ice FAX; 120/576 |
| 1200 | USCG New Orleans, LA | NMG/NMG-2 | 17146.4 kHz | UNITED STATES - Atlantic and Gulf | Weather FAX*; 120/576 |
| 1400 | Murmansk | UDK/UDK2 | 6446, 7907, 8444 kHz | RUSSIA - Northern Coasts | Weather and ice FAX*; 120/576 |
| 1400 | USCG Point Reyes, CA | NMC/NMC-17 | 4346 kHz | UNITED STATES - Pacific | Weather FAX*; 120/576 |
| 1400 | USCG Boston, MA | NMF/NIK/NMF-7 | 12750 kHz | UNITED STATES - Atlantic and Gulf | Weather FAX*; 120/576 |
| 1430 | Murmansk | UDK/UDK2 | 6446, 7907, 8444 kHz | RUSSIA - Northern Coasts | Weather and ice FAX*; 120/576 |
| 1430 | Pevek | 148 kHz | RUSSIA - Northern Coasts | Ice FAX, 90/576 | |
| 1520 | Offenbach/Pinneberg | DDH/DDK | 3855, 7880, 13882.5 kHz | GERMANY - North Sea | Ice FAX*; 120/576 |
| 1530 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 18238 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 1530 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 7508, 13538 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 1540 | Offenbach/Pinneberg | DDH/DDK | 3855, 7880, 13882.5 kHz | GERMANY - North Sea | Ice FAX*; 120/576 |
| 1600 | USCG Boston, MA | NMF/NIK/NMF-7 | 6340.5, 9110, 12750 kHz | UNITED STATES - Atlantic and Gulf | Ice FAX; 120/576 (Feb. - Aug.) |
| 1600 | Kodiak, AK | NOJ | 2054, 4298, 8459, 12412.5 kHz | Weather and ice FAX*; 120/576 | |
| 1630 | Rio de Janeiro Naval | PWZ-33 | 12665, 16978 kHz | BRAZIL | Weather FAX; 120/576 |
| 1630 | Valparaiso Playa Ancha | CBV | 4228, 8677, 17146.4 kHz | CHILE | Weather FAX; 120/576 |
| 1630 | Inuvik, N.W.T. | VFA | 8457.8 kHz | CANADA - Arctic and Atlantic | Weather and ice FAX; 120/576 |
| 1645 | Valparaiso Playa Ancha | CBV | 4228, 8677, 17146.4 kHz | CHILE | Weather FAX; 120/576 |
| 1719 | Honolulu, HI | KVM70 | 16135 kHz | UNITED STATES - Hawaii | Weather FAX*; 120/576 |
| 1741 | Sydney, N.S. | VCO | 6915.1 kHz | CANADA - Arctic and Atlantic | Ice FAX; 120/576 |
| 1810 | USCG Boston, MA | NMF/NIK/NMF-7 | 6340.5, 9110, 12750 kHz | UNITED STATES - Atlantic and Gulf | Ice FAX; 120/576 (Feb. - Aug.) |
| 1840 | USCG Point Reyes, CA | NMC/NMC-17 | 22527 kHz | UNITED STATES - Pacific | Weather FAX*; 120/576 |
| 1900 | Charleville | VMC | 20469 kHz | AUSTRALIA | Weather FAX*; 120/576 |
| 1900 | Northwood, UK | GYA | 11086.5 | EUROPE | Weather FAX; 120/576 |
| 1915 | Valparaiso Playa Ancha | CBV | 4228, 8677, 17146.4 kHz | CHILE | Weather FAX; 120/576 |
| 1930 | Valparaiso Playa Ancha | CBV | 4228, 8677, 17146.4 kHz | CHILE | Weather FAX; 120/576 |
| 2000 | Murmansk | UDK/UDK2 | 6446, 7907, 8444 kHz | RUSSIA - Northern Coasts | Weather and ice FAX*; 120/576 |
| 2100 | Offenbach/Pinneberg | DDH/DDK | 3855, 7880, 13882.5 kHz | GERMANY - North Sea | Ice FAX*; 120/576 |
| 2100 | Wiluna | VMW | 18060 kHz | AUSTRALIA | Weather FAX*; 120/576 |
| 2100 | Iqaluit, N.T. | VFF | 3251.1, 7708.1 kHz | CANADA - Arctic and Atlantic | Weather FAX; 120/576 |
| 2115 | Offenbach/Pinneberg | DDH/DDK | 3855, 7880, 13882.5 kHz | GERMANY - North Sea | Ice FAX*; 120/576 |
| 2125 | Iqaluit, N.T. | VFF | 3251.1, 7708.1 kHz | CANADA - Arctic and Atlantic | Ice FAX; 120/576 |
| 2150 | Kodiak, AK | NOJ | 2054, 4298, 8459, 12412.5 kHz | Weather and ice FAX*; 120/576 | |
| 2200 | Sydney, N.S. | VCO | 4416 kHz | CANADA - Arctic and Atlantic | Ice FAX; 120/576 |
| 2200 | Valparaiso Playa Ancha | CBV | 4228, 8677, 17146.4 kHz | CHILE | Weather FAX; 120/576 |
| 2215 | Valparaiso Playa Ancha | CBV | 4228, 8677, 17146.4 kHz | CHILE | Ice FAX; 120/576 |
| 2222 | Halifax, N.S. | VCS/CFH | 122.5 MHz, 4271, 6496.4, 10536, 13510 kHz | CANADA - Arctic and Atlantic | Ice FAX*; 120/576 |
| 2230 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 4014 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 2230 | Cape Naval (NAVCOMCEN Cape) | ZSJ | 7508, 13538 kHz | SOUTH AFRICA | Weather FAX*; 120/576 |
| 2230 | Valparaiso Playa Ancha | CBV | 4228, 8677, 17146.4 kHz | CHILE | Weather FAX; 120/576 |
| 2301 | Halifax, N.S. | VCS/CFH | 122.5 MHz, 4271, 6496.4, 10536, 13510 kHz | CANADA - Arctic and Atlantic | Ice FAX*; 120/576 |
| 2310 | Valparaiso Playa Ancha | CBV | 4228, 8677, 17146.4 kHz | CHILE | Weather FAX; 120/576 |
| 2320 | USCG Point Reyes, CA | NMC/NMC-17 | 22527 kHz | UNITED STATES - Pacific | Weather FAX*; 120/576 |
| 2325 | Valparaiso Playa Ancha | CBV | 4228, 8677, 17146.4 kHz | CHILE | Weather FAX; 120/576 |
| 2330 | Iqaluit, N.T. | VFF | 3251.1, 7708.1 kHz | CANADA - Arctic and Atlantic | Weather FAX; 120/576 (Resolute) |
| 2331 | Sydney, N.S. | VCO | 4416 kHz | CANADA - Arctic and Atlantic | Ice FAX; 120/576 |
Gallery of FAX receptions
 DDK3 on 7780.0 kHz |
 GYA on 11086.5 kHz |
GYA on 12390.0 kHz |
References
- Multimode image and data decoding software for soundcards
- 'Radio printing' sent newspapers through the waves
- First daily newspaper by Radio Facsimile
- Deutscher Wetterdienst FAX broadcasts for shipping
External links
- Typically around 3 to 16 MHz. See here for Yachtcom UK Weatherfax frequencies.
- NOAA Worldwide Radiofax Guide
- USCG Marine Weather Broadcasts Note: Click on the USCG Radiofax link
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