Abstract: Tone detection circuitry including tone decoder providing a free running frequency determined by timing resistance and timing capacitance connected to it. A control means including a programmable microprocessor establishes a retrieval record based on the product of the timing resistance and timing capacitance needed to establish the center frequency of the tone decoder for a plurality of bandwidths. The retrieval record is used to establish the product of the timing resistance and timing capacitance when a tone within the selected bandwidth is to be detected.

Abstract: A drum-type transceiver facsimile machine having a plurality of light-to-electric transducers and a plurality of printing styli moved axially of the drum for scan/print operation. Shift register means and a buffer memory controlled by a programmed microprocessor provide for multiplexing of signals from the transducers having a scan operation and demultiplexing of signals during the print mode with use of a buffer memory permitting compression of the multiplexed signals and decompression of received signals prior to demultiplexing.

Abstract: A bi-directional subscan drive control for a drum-type facsimile machine utilizing a single, bi-directional, electrically controlled stepping motor for driving the scan head of the facsimile machine in one direction at any of a plurality of possible rates during a scanning operation and for driving the scan head in the opposite direction at a much higher rate upon completion of the scanning operation. The stepping motor is operated to provide at last two steps for each revolution of the drum when operated in the one direction.

Abstract: A method and system for altering the phase difference between a local motor and a remote motor wherein the phase difference is determined in terms of a count made of reference pulses at a first frequency when both motors are operating at a predetermined speed that is directly related to the first frequency. A phase altering count is determined from the phase difference count indicative of the degree to which the phase difference is to be altered and the reference pulses are produced at the local motor at a second frequency to alter the speed of the local motor. The phase altering count and the reference pulses at the second frequency are used to establish a time interval for operation of the stepping motor sufficient to make the desired change in the phase difference.