Facsimile Transmission
Roger L. Freeman · 2002
Abstract Facsimile (fax) is a method of electrical communication of graphic information. It is used to transmit pictorial or printed matter from one location to another with reasonably faithful copy recorded at the receiving end. Fax has been designed primarily to operate over comparatively narrow‐band media, lending itself to transmission over the telephone network on the standard 4‐kHz voice channel and on HF radio. Facsimile is transmitted in either (a) black and white or (b) black and white with various shades of gray. One system in operation has 256 shades of gray. Fax has truly become ubiquitous in many parts of the world. This chapter is primarily concerned with facsimile interface data and standards, derived primarily from ITU‐T (CCITT) and US military documents. Another source is the US Electronic Industries Association (EIA). However, much of the EIA material is similar to ITU‐T Recommendations, and for that reason it has not been included.