Today, radiofax is primarily used worldwide for the dissemination of weather charts, satellite weather images, and forecasts to ships at sea. The stop tone, optionally followed by black, marks the end of the transmission.

The phasing signal, consisting of a periodic pulse, synchronises the receiver so that the image will be centered on the paper.It consists of rapid modulation of the video carrier, resulting in a characteristic rasp-like sound. It was originally meant to allow enough time for the drum of mechanical systems to get up to speed. The start tone triggers the receiving system.It is employed by most terrestrial weather facsimile stations as well as geostationary weather satellites. Usually the IOC is 576.ДЄutomatic Picture Transmission format (APT)ДЄPT format permits unattended monitoring of services. 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 ПЂ (3.1416). Usually, 120 lines per minute (LPM) are sent (For monochrome fax, possible values are: 60, 90, 100, 120, 180, 240. 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.ДЇacsmile 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). Prices obviously relate those prevailing when the receivers were reviewed.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. ( Please note that these reviews may include certain information, such as manufacturer contact details, that are now out of date. Interestingly, in the years since publication some receivers have vanished without trace yet others not only soldier on but have a well-earned place in receiver history. Neither Radio Netherlands or the Medium Wave Circle has any financial connection with any of the manufacturers listed. Netherlands).ДЄll the reviews have been carried out by independent reviewers. The reviews were coordinated by the Media Network team at Radio Nederland Wereldomroep (R. They are provided here for those who are looking for information on pre-owned receivers. The receiver reviews listed on this page were originally published on the Radio Netherlands website before the year 2000 but are re-published here following the loss of their original home. Legacy Receiver Reviews The Radio Netherlands Collection

Freeware weather fax receiver