FASTFAX, a Second Generation Facsimile System Employing Redundancy Reduction Techniques

A digital coded facsimile system has been developed employing redundancy reduction techniques to reduce the timebandwidth product requirement over conventional facsimile by a factor of 5 to 1 for an average complexity document. Experimental results are presented which illustrate the feasibility of technique using subframe variable velocity raster scanning, fiber optics contact printing, and a simple, but efficient, coding algorithm whose choice was based on the results of an extensive statistical analysis program. The terminal operates at two data speeds 50 Kbit/s and 4800 bit/s and can transmit an average - by ll-inch document, scanned at 135 lines per inch resolution in 7 seconds over group channels and in 70 seconds over voice bandwidth channels.