Question:
A carrier wave $\mathrm{V}_{\mathrm{C}}(\mathrm{t})=160 \sin \left(2 \pi \times 10^{6} \mathrm{t}\right)$ volts is made to vary between $\mathrm{V}_{\max }=200 \mathrm{~V}$ and $\mathrm{V}_{\min }=120 \mathrm{~V}$ by a message signal $\mathrm{V}_{\mathrm{m}}(\mathrm{t})=\mathrm{A}_{\mathrm{m}} \sin \left(2 \pi \times 10^{3} \mathrm{t}\right)$ volts. The peak voltage $A_{m}$ of the modulating signal is_______.
Solution:
Maximum amplitude
$A_{\max }=A_{m}+A_{C}$
$\Rightarrow V_{\max }=V_{m}+V_{C}$
$200=\mathrm{V}_{\mathrm{m}}+160$
$\mathrm{V}_{\mathrm{m}}=40$
$\therefore$ Peak voltage $A_{m}=40$
Ans. 40