Question

An analog signal is bandlimited to 4 KHz, sampled at Nyquist rate and the samples are quantized into 4 levels. The quantized levels are assumed to be independent and equally probable. If we transmit two quantized samples per sec, the information rate is
1. 1 bit / s
2. 2 bit / s
3. 3 bit / s
4. 4 bit / s

Answer 1

Correct Answer - Option 4 : 4 bit / s

Entropy for equiprobable and independent bits.

\(H = {\log _2}N = {\log _2}4 = 2~bits/symbol\)

Now, two symbols are transmitted per second.

So,Information rate = rH = 2 × 2 = 4 bit/s.