64 lines
1.8 KiB
Markdown
64 lines
1.8 KiB
Markdown
---
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title: "Code rate"
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chunk: 1/1
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source: "https://en.wikipedia.org/wiki/Code_rate"
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category: "reference"
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tags: "science, encyclopedia"
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date_saved: "2026-05-05T11:31:47.594641+00:00"
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instance: "kb-cron"
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---
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In telecommunication and information theory, the code rate (or information rate) of a forward error correction code is the proportion of the data-stream that is useful (non-redundant). That is, if the code rate is
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k
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/
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n
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{\displaystyle k/n}
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, for every k bits of useful information, the coder generates a total of n bits of data, of which
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n
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−
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k
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{\displaystyle n-k}
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are redundant.
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If R is the gross bit rate or data signalling rate (inclusive of redundant error coding), the net bit rate (the useful bit rate exclusive of error correction codes) is
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≤
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R
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⋅
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k
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/
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n
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{\displaystyle \leq R\cdot k/n}
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.
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For example: The code rate of a convolutional code will typically be 1⁄2, 2⁄3, 3⁄4, 5⁄6, 7⁄8, etc., corresponding to one redundant bit inserted after every single, second, third, etc., bit. The code rate of the octet oriented Reed Solomon block code denoted RS(204,188) is 188/204, meaning that 204 − 188 = 16 redundant octets (or bytes) are added to each block of 188 octets of useful information.
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A few error correction codes do not have a fixed code rate—rateless erasure codes.
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Note that bit/s is a more widespread unit of measurement for the information rate, implying that it is synonymous with net bit rate or useful bit rate exclusive of error-correction codes.
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== See also ==
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Entropy rate
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Information rate
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Punctured code
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== References == |