Question

A signal of frequency $10\, kHz$ and peak voltage $10\, V$ is used to amplitude modulate a carrier of frequency $1\, MHz$ and peak voltage $20\, V$. The side-band frequencies in $kHz$ are

• A. 1010, 990
• B. 910, 1090
• C. 10, 11
• D. 1.01, 0.99

Answer 1

Answer: (A)

Given, frequency of signal, $f_{s}=10\, kHz$
peak voltage, $V_{p}=10 \,V$
carrier frequency, $f_{c}=1 \,mHz$
and peak voltage, $V_{c}=20 \,V$
$\therefore $ The side band frequencies are given as
$f=f_{c} \pm f_{s}$
Putting the given values, we get
$f=1 \times 10^{6} \pm 10 \times 10^{3} Hz =(1000 \pm 10) 10^{3}\, Hz$
So, the side band frequencies in $kHz$ is $1010 \,kHz$ and $990\, kHz$.