Abstract: A facsimile transmitter capable of transmitting graphic as well as text material, by telephone or wireless. A digital code derived from scanning the document to be transmitted is truncated from eight bits per pixel to six bits per pixel. The three most significant bits of each pixel are run length encoded in eight bit bytes, so that wherever the same three most significant bits appear in adjacent pixels, these three bits are transmitted once, followed by a five bit code indicating the number of times (up to 32 times) the same three most significant bits are repeated in succeeding pixels. The resulting eight bit bytes are similarly run length encoded, so that the transmission of the three most significant bits of each pixel is double run length encoded. An eight bit fine resolution byte is transmitted for each eight pixels.

Abstract: A facsimile receiver of the type in which a laser beam modulated by a received video signal scans a light sensitive recording paper to print an image corresponding to the video signal. A feedback loop insures that the output of the laser beam acousto-optical modulator (AOM) accurately tracks the demodulated received video signal. A variable transmissivity filter in the path of the laser beam is automatically positioned to provide increased transmittance as the laser beam intensity decreases with aging of the laser, so as to maintain a constant light output intensity. A lens in the optical system which focuses the laser beam on the paper is moved mechanically as the paper is transversely scanned, so that the focus of the beam is varied to compensate for the planar (non-cylindrical) configuration of the paper, thus keeping the beam focused on the paper throughout the length of each scan line.

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.