ARQ-M
radio telegraph protocol
ARQ-M, short for Automatic Repeat reQuest, Multiplex, is a radio telegraphy protocol used to reliably forward telex messages over partially reliable radio links. It is a low-speed system designed to match the performance of landline telex systems and allow those messages to be forwarded over long distances using shortwave radios. The first ARQ-M link was built in the Netherlands, and began exchanging messages with a counterpart in New York in 1947.
ARQ-M is similar in concept to ARQ-E, but ARQ-E has no multiplex capability and uses a different 7-bit alphabet.
History
The telex system, which developed out of the telegraph system, is based on defined electric current levels that are interpreted as a mark or space signal. These are normally sent over well-defined networks with considerable infrastructure that keeps error rates very low. In contrast, radio communications are subject to a wide variety of noises and other signal problems that leads to losses. To forward telex messages successfully over radio links, some form of error correction should be applied.
ARQ-M was developed to automatically deal with errors. The automatic repeat request system was invented by Hendrik van Duuren of the Netherlands in the 1940s and so it became known as the Van Duuren automatic error correction system.
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Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Aug 14, 2026. The linked authority identifier is Q18349456. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1947.
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This entry incorporates text from “ARQ-M” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.