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Chapter 22
Error Detecting
andCorrecting Codes
22.1 PARITY CHECK CODES
We can enjoy chats with friends even in noisy pubs. Even if we cannot
hear some sounds of words, we can usually understand each other. Since
any language has some redundancy, we can usually guess the meaning
of sentences containing some missing sounds or missing words if the
missing sounds/words are not too many, or we can ask, “Pardon me, could
you please repeat what you said?” ese kinds of techniques are also useful
in data communications and data processing in digital circuits.
A parity bit in a binary code word is a bit added to ensure that the
number of bits w