Radiofax

Analogue mode for transmitting monochrome images

Radiofacsimile, radiofax or HF fax is an analogue mode for transmitting grayscale images via high frequency (HF) radio waves. It was the predecessor to slow-scan television (SSTV). It was the primary method of sending photographs from remote sites from the 1930s to the early 1970s. It is still in limited use for transmitting weather charts and information to ships at sea.

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