Code rate

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The code rate or information rate of a forward error correction (FEC) code, for example a convolutional code, states what portion of the total amount of information that is useful (non redundant). The code rate is typically a fractional number. If the code rate is k/n, for every k bits of useful information, the coder generates totally n bits of data, of which n-k are redundant. If R is the net bitrate (useful bitrate), the gross bitrate (raw bitrate) is R•n/k.

For example: The code rate of a convolutional code may typically be 1/2, 2/3, 3/4, 5/6, 7/8, etc. The code rate of Reed Solomon Block code may for instance be 188/204.