Question

In the amplitude modulation mode of transmission, the normal speed signal is with a maximum frequency of $5kHz$. If the carrier frequency is $200kHz$, 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
• E. 199.5 kHz to 200.5 kHz

Answer 1

Answer: (B)

Given, carrier wave frequency $f_c=200kHz$
and message signal frequency $f_m=5kHz$.
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
$f_{\max }=200+5=205kHz$
and $f_{\min }=200-5=195kHz$