Communication System Question 3
Question 3 - 25 January - Shift 1
A message signal of frequency $5 kHz$ is used to modulate a carrier signal of frequency 2 MHz. The bandwidth for amplitude modulation is:
(1) $5 kHz$
(2) $20 kHz$
(3) $10 kHz$
(4) $2.5 kHz$
Show Answer
Answer: (3)
Solution:
Formula: Band width
Given
Signal frequency $f_m=5 kHz$
Carrier wave frequency $f_c=2 MHz$
$f_c=2000 KHz$
The resultant signal will have band width of frequency given by
$[(f_c+f_m)-(f_c-f_m)]$
$\Rightarrow[(2000+5)-(2000-5)] kHz$
$\Rightarrow 10 kHz$
