US 4,048,657 AGranted

Method and apparatus for synchronizing a facsimile transmission

AssigneeTeletype Corporation

InventorKurt E. Knuth

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Abstract

A facsimile transmission system is described which includes a transmitter section having an optical sensor driven across a selected document by a variable speed motor controlled by the frequency of an oscillator. The relative movement of the sensor with respect to the document is indicated by a pulse generator which clocks the output of the sensor into a storage memory. The stored data is clocked from the storage memory by the oscillator output and fed, along with the oscillator signal, to a diphase modulator. At a receiver section, the diphase signal is demodulated providing data and clock signals. The data signal is placed into a receiver storage memory. The clock frequency is used to control the speed of a recorder motor driving a recorder. A pulse generator is coupled to the recording device and generates recorder location pulses which are used to clock the data from the memory.

Claims6

Dependent claims

An apparatus for facsimile communications comprising:

a sensor positioned adjacent a selected document and selectively movable along the document, said sensor generating a signal corresponding to the reflective qualities of sampled, selected areas of the document;
means for successively storing a series of the signals from said sensor;
means for reading out said stored signals from said storage means at a predetermined rate whereby the variations in the signal rate from the sensor are substantially eliminated by said storage means thus producing a constant output rate from said storage means;
a motor for positioning said sensor with respect to the document;
means for generating a predetermined frequency, serving to determine the speed of the motor, said frequency generating means controlling the readout rate of the storage means so that the sample rate of said sensor is related to the output rate of data from said storage means;
means, coupled to said motor, for generating a signal corresponding to the relative position of said sensor with respect to the document, said signal generating means being coupled to the storage means and serving to control the rate at which the output from the sensor is fed into the storage means;
an analog to digital converter receiving the analog output of said sensor and feeding a multilevel digital signal to said storage means;
a parallel to serial converter receiving the multilevel digital signal from said storage means;
and
a diphase modulator receiving the serial output from said converter and the predetermined signal from said frequency generating means and providing a diphase signal in accordance therewith.

7 more elements

Dependencies are inferred from the claim text.