Question

In the amplitude modulation mode of transmission, the normal speed signal is with a maximum frequency of $5\, kHz$. If the carrier frequency is $200\, kHz$, the modulated signal will have the frequencies varying between

• A. 190 kHz to 210 kHz
• B. 195 kHz to 205 kHz
• C. 195 kHz to 200 kHz
• D. 200 kHz to 205 kHz

Answer 1

Answer: (B)

195 kHz to 205 kHz

Answer 2

Given, carrier wave frequency $f_{c}=200 \,kHz$
and message signal frequency $f_{m}=5 \,kHz$.
In amplitude modulation the lower and upper side frequencies are given as,
$f_{\max }=f_{c}+f_{m}$
and $f_{\min }=f_{c}-f_{m}$
So, by putting the values, we get
$f_{\max }=200+5=205 \,kHz$
and $f_{\min }=200-5=195 \,kHz$