Question

A 100 kbps data is to be transmitted through a baseband channel, whose bandwidth is 75 kHz. If the raised cosine pulse shaping is used for baseband modelling of the data, then the maximum allowed value of the roll-off factor of the filter will be

• A. 0.26
• B. 0.11
• C. 0.5
• D. 0.33

Answer 1

The correct option is C 0.5

$\begin{array}{cc}(BW{)}_{signal}& =\frac{R_b}{2}(1+\alpha )=\frac{100}{2}(1+\alpha )\\ & =50\times (1+\alpha )\\ (1+\alpha )\times 50& \le 75\\ 1+\alpha & \le \frac{75}{50}\\ 1+\alpha & \le 1.5\\ \alpha & \le 0.5\end{array}$