Portable facsimile transmitter

Abstract

A portable facsimile transmitter suitable for use by reporters and photographers in the field, for sending high quality pictures to an unattended remote receiver, by telephone or wireless. A rotating drum to which the original is affixed is initially scanned at a rapid rate to establish the photodetector operating level so as to maximize the signal dynamic range. After the initial scan the picture is scanned at one of three selectable rates (determined by setting the drum speed), and the video output of the photodetector is modulated and coupled to the transmission line. The original is affixed to the drum by means of a fixed (with respect to the drum) clamp and a movable clamp at each end thereof. A tab extends from an end of each clamp, and the position of each tab is sensed to provide a synchronization signal so that the picture is centered at the remote receiver. A protective circuit begins to measure the drum rotation speed a predetermined time after scanning begins, and terminates transmission if the speed is improper. Picture transmission can be initiated by a command signal from the remote receiver. A reference code identifying the particular transmitter and the place of transmission can be transmitted with each picture.