Information Theory and Coding > Entropy > What is Information rate?

Information rate

If the source is emitting symbols at a fixed rate of r_s  symbols / sec, the average source information rate ‘R’ is defined as

 R = r_s* H bits / sec

 

Example:

An analog signal is band limited to B Hz, sampled at the Nyquist rate, and the samples are quantized into 4-levels. The quantization levels Q₁, Q₂, Q₃, and Q₄ (messages) are assumed independent and occur with probs. P₁ = P₂ = 1/8 and P₂ = P₃ = 3/8 . Find the information rate of the source.

By definition, the average information H is given by

H= 1.8 bits/ message

Information rate of the source by definition is R = r_s H

R = 2B* (1.8) = (3.6 B) bits/sec

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