#### Question 7.7 Question 7.8

# 7.3 Block coding

## Basics of block coding

The terminology for block coding is that an input block of k bits gives rise to an output block of n bits and this is called an (n,k) code. This increase in block length means that the useful data rate (the information transfer rate) is reduced by a factor k/n. This is called the rate of the code.

#### Code rate R = k/n

#### The additional data bits are carefully chosen such that they help differentiate one pattern of k bits in a block from a different pattern of k input bits. The factor (1 – k/n) is usually termed the redundancy of the block code.

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