Abstract : The paper discusses an experimental unit which incorporates error correcting coding into digital data communication systems for increased reliability. A short, random correcting block code is used in this unit. The code is taken from the class of Euclidean geometry codes which can be decoded by simple majority logic. The unit is complete with an encoder whixh encodes a block of information digits into a codeword before transmission, a decoder which determines from each codeword the information digits it contains, and an error generator which simulates a noisy channel. For demonstration purposes teletype machines will be used as the data source and the destination of this unit. (Author)