Question

A carrier wave of peak voltage $12V$ is used to transmit a message signal. The peak voltage of the modulating signal in order to have a modulation index of $75\%$ is

• A. $8V$
• B. $6V$
• C. $7V$
• D. $9 \, V$

Answer 1

Answer: (D)

Here $A_{c}=12V$ , $A_{m}=?$
modulation index $\mu _{c}=75\%=0.75$
Since $\mu _{c}=\frac{A_{m}}{A_{c}}\Rightarrow 0.75=\frac{A_{m}}{12}$
$A_{m}=0.75\times 12=9V$