Question

Four voice signals, each limited to 4 kHz and sampled at Nyquist rate, are converted into binary PCM signal using 256 quantization levels. The bit transmission rate for the time-division multiplexing signal will be

1. 8 kbps
2. 64 kbps
3. 256 kbps
4. 5126 kbps

Answer 1

Correct Answer - Option 3 : 256 kbps

Concept:

Transmission rate (R_b)

= \({{nm{f_s}}}\)

n → number of bits in the signal

m → number of signals

fs → sampling frequency

Calculation:

Given:

No. of levels of PCM = 256

∴ no. of bits = log₂ 256

= 8 bits

m = 4

fs = (2f_m) = 8 kHz

\(R_b = ({{8 \;\times\; 4 \;\times\; 8}})~ kbps\)

= 256 kbps