NWS Marine Radiofax Service
Weather Products Via HF Fax, Marine Radiofacsimile or Weatherfax
Marine Radiofax is a service provided by the Coast Guard and National Weather Service to broadcast weather charts and forecast information to vessels at sea.
Marine Weather Radiofax, additionally referred to as HF FAX, radiofacsimile or weatherfax, is a method used to broadcast and receive weather graphics like forecast maps, charts or satellite images via High Frequency (HF) radio for use of ships at sea. Facsimile images are received as radio signals on a shortwave or dedicated radiofax receiver and decoded by an external facsimile recording device or a personal computer equipped with the proper interface and decoding software. Facsimile is a method of transmitting photos and images through a process of scanning, signal encoding, transmission, decoding and printing. Radiofax is only little different than the office fax machine.
Equipment - Major radio manufacturers like Alden, Japan Radio Company (JRC), Furuno, Taiyo and Universal Radio are among many that produce and supply dedicated radiofax hardware. There are numerous providers of personal computer interfaces and software needed for decoding radiofax transmissions. A current list of equipment providers is available at the Worldwide Radiofacsimile and SSTV webpage. Some radiofax software is also capable of decoding the text weather forecasts broadcast by the Coast Guard using HF Simplex Teletype Over Radio (SITOR).
Background - Marine radiofacimile broadcasts were first made by Charles Francis Jenkins for the Navy in 1926. By 1930, the U.S. Weather Bureau had furthered its tests and use of radiofacimile technology. Following in the footsteps of the old Weather Bureau, the National Weather Service – Ocean Prediction Center now prepares weather maps of the high seas, satellite imagery, sea surface temperature and text forecasts for broadcast by Coast Guard and Department of Defense transmitter stations. Modern technology now makes these Ocean Prediction Center products available via the Internet through e-mail, the web and file transfer protocol (FTP). Many vessels can receive these internet services while at sea.
Standards - The National Weather Service (NWS) broadcasts a radiofax signal of 120 lines per minute (LPM) and an Index of Cooperation (IOC) of 576. Standards vary in broadcasts from Russia and North Korea. Users of radiofax equipment or signal decoders need these values to display the images properly. Worldwide marine radiofacsimile broadcast schedules in PDF format are available online. The National Weather Service depends on observers in the Voluntary Observing Ship (VOS) for meteorological data and to refine marine forecasts used to prepare their products.
The Future - The U.S. Coast Guard is considering discontinuing its High Frequency Radio Broadcasts provided for mariners at sea of marine weather forecasts and warnings through radiofax, voice, and simplex teletype over radio (SITOR) formats. Coast Guard transmitting equipment is old and difficult to repair. The Agency wants a sense of the importance of this technology to the maritime community before it invests in new radio equipment. The future of radiofax is part of an unknown forecast.
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