Question

A message signal x(t) is given to the PCM system where $x\left(t\right)=40\cos 3\times {10}^3\pi t$. Raised cosine pulse is used to represent the binary sequence. Find the transmission B.W (in kHz). If sampling is done at Nyquist rate and each sample is encoded with 4-bit and roll-off factor, $\alpha$=0.25.

• A. 6
• B. 3.75
• C. 7.5
• D. 1.5

Answer 1

The correct option is C 7.5

(d)

$B.W.=\frac{R_b}{2}[1+\alpha ]$

$R_b=n{f}_s=n\times 2\times f_m=4\times 2\times 1.5\times {10}^5=12kbps$

$\therefore$ $B.W=6\left[1.25\right]=7.5kHz$