Question

A signal of frequency $10kHz$ and peak voltage $10V$ is used to amplitude modulate a carrier of frequency $1MHz$ and peak voltage $20V$. 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, $f_s=10kHz$
peak voltage, $V_p=10V$
carrier frequency, $f_c=1mHz$
and peak voltage, $V_c=20V$
$\therefore$ 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 $1010kHz$ and $990kHz$.