Communication System Question 7
Question 7 - 31 January - Shift 1
The amplitude of $15 \sin (1000 \pi t)$ is modulated by $10 \sin (4 \pi t)$ signal. The amplitude modulated signal contains frequency(ies) of
(A) $500 Hz$
(B) $2 Hz$
(C) $250 Hz$
(D) $498 Hz$
(E) $502 Hz$
Choose the correct answer from the options given below:
(1) A only
(2) A, D and E only
(3) B only
(4) A and B only
Show Answer
Answer: (2)
Solution:
Formula: Frequency Modulation
Carrier wave frequency
$V_C=\frac{100 \pi}{2 \pi}=500 Hz$
Modulating wave frequency
$ \begin{aligned} & V_m=\frac{4 \pi}{2 \pi}=2 Hz \\ & \therefore \quad V_C-V_m, V_C, V_C+V_m \\ & \quad=498 Hz .500 Hz, 502 Hz \end{aligned} $
