Abstract: A scanning array (12) comprising a plurality of photosensor elements (12a) is reciprocated perpendicular to the axis (12b) thereof to scan a rectangular area of an original document (69). After scanning the area, the document (69) is moved parallel to the axis (12b) of the scanning array (12) and the scanning array (12) reciprocated again to scan a next rectangular area. This process is continued until the entire document (69) is scanned. The photosensor elements (12a) produce data signals corresponding to incident light from the document (69) which are fed serially into an orthogonal conversion memory (26) in the column direction. The data signals are read out of the memory (26) in the row direction and run length encoded for transmission. Received data signals are run length decoded and fed into the memory (26) in the row direction and read out of the memory (26) in the column direction.

Abstract: In a system of transceivers which can automatically operate either in calling or called modes, the identification codes of the calling and called transceivers are transmitted back and forth between them and compared in a manner which tends to minimize erroneous connections and to confirm only correct connections prior to starting the actual transmission of data between the transceivers.

Abstract: A data terminal is connected to a telephone line for data transmission and reception. When a malfunction is detected in the data terminal, the data terminal is automatically disconnected from the telephone line and a telephone set connected to the telephone line. After a predetermined time interval, the telephone set is automatically disconnected from the telephone line and the data terminal re-connected to the telephone line.