The official ITU radio emission designation is F1C.

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.

A deviation less than that for a white or black pixel is taken to be a shade of grey. The signal shifts up or down a given amount to designate white or black pixels. Radiofax is transmitted in single sideband and uses frequency modulation. 2 Automatic Picture Transmission format (APT).The German Meteorological Service (DWD) is another major producer of FAX charts, which are also transmitted on HF frequecies from a location near Kiel. Radio weatherfax transmissions are particularly useful to shipping, where there are limited facilities for accessing the Internet. Radiofax transmissions are also broadcast by NOAA from multiple sites in the USA at regular daily schedules. 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). 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. 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. 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. Many of these products are used in conjunction with maritime weather transmissions in SSB voice (almost always USB mode) and RTTY.įacsmile machines were used in the 1950s to transmit weather charts across the United States via land-lines first and then internationally via HF radio.

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). It is also related to slow-scan television ( SSTV). 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.

Rtty news frequencies