Editing Self-synchronizing code (section)

{{Use American English|date=March 2019}}
{{Short description|Type of code in coding theory}}
{{Use dmy dates|date=March 2019|cs1-dates=y}}
{{Use list-defined references|date=August 2023}}
{{Distinguish|Self-clocking signal|Self-similar process}}

In [[coding theory]], especially in [[telecommunications]], a '''self-synchronizing code''' is a [[uniquely decodable code]] in which the [[symbol (data)|symbol]] stream formed by a portion of one [[Code word (communication)|code word]], or by the overlapped portion of any two adjacent code words, is not a valid code word.<ref name="Glossary"/> Put another way, a set of strings (called "code words") over an alphabet is called a self-synchronizing code if for each string obtained by concatenating two code words, the substring starting at the second symbol and ending at the second-last symbol does not contain any code word as substring. Every self-synchronizing code is a [[prefix code]], but not all prefix codes are self-synchronizing.

Other terms for self-synchronizing code are '''synchronized code'''<ref name="Brestel-Perrin-Reutenauer_2010"/> or, ambiguously, '''comma-free code'''.<ref name="Brestel-Perrin_1985"/> A self-synchronizing code permits the proper [[frame synchronization|framing]] of transmitted code words provided that no uncorrected errors occur in the [[data stream|symbol stream]]; external [[synchronization]] is not required. Self-synchronizing codes also allow recovery from uncorrected errors in the stream; with most prefix codes, an uncorrected error in a single [[bit]] may propagate errors further in the stream and make the subsequent data [[data corruption|corrupted]].

Importance of self-synchronizing codes is not limited to [[data transmission]]. Self-synchronization also facilitates some cases of [[data recovery]], for example of a [[character encoding|digitally encoded text]].