Automatic error correction on radio telegraph circuits

The reliability of high frequency radio telegraph systems has always been a limitation in international communications. Transmission errors are liable to result from the vagaries of propagation via the ionospheric transmission medium, and from interference. Until recently reliable service for public telegraph traffic has been achieved by high operating standards, with visual inspection of received messages, and correction of errors by repetition on request. This procedure results in poor circuit efficiency, and high operating costs. The demand for international telex and leased circuits in recent years has required the provision of circuits having high transmission accuracy. These demands have given considerable impetus to the development of error correcting telegraph systems. In 1956 at Warsaw the C.C.I.R. recommended the system developed by Doctor H.O.A. van Duuren of the Netherlands for international standardisation. Since that date equipment operating on the van Duuren principle has been installed on most important radio telegraph circuits.