Abstract: A black and white facsimile communication system wherein the document to be transmitted is scanned line by line, the scanner signals are sampled to obtain pulse sequences having a constant number of pulses for every line. The pulse sequences are converted into codewords for redundancy reduction. The codewords are transmitted and, in the receiver, reconverted into pulse sequences which control reproduction. Before reproduction every pulse sequence obtained by reconversion is tested whether it contains the correct number of pulses. If that is not the case, the last reproduced line is reproduced again instead of the line received with an error.