Error detection and correction

In information theory and coding theory with applications in computer science and telecommunication, error detection and correction or error control are techniques that enable reliable delivery of digital data over unreliable communication channels. Many communication channels are subject to channel noise, and thus errors may be introduced during transmission from the source to a receiver. Error detection techniques allow detecting such errors, while error correction enables reconstruction of the original data in many cases.

Definitions

The general definitions of the terms are as follows:

History

An early systematic use of error detection was by Jewish scribes in the precise copying of the Jewish bible, beginning before Christ. An emphasis on minute details of words and spellings evolved into the idea of a perfect text in 135 CE, and with it increasingly forceful strictures that a deviation in even a single letter would make a Torah scroll invalid. The scribes used methods such as summing the number of words per line and per page (Numerical Masorah), and checking the middle paragraph, word and letter against the original. The page was thrown out if a single mistake was found, and three mistakes on a single page would result in the entire manuscript being destroyed (the equivalent of retransmission on a telecommunications channel). The effectiveness of their methods was verified by the accuracy of copying through the centuries demonstrated by discovery of the Dead Sea Scrolls in 1947–1956, dating from c.408 BCE-75 CE.