Question

If the modulating frequency of a carrier wave varies between 700Hz and 7KHz, find it’s bandwidth?

(a) 10 KHz

(b) 23 KHz

(c) 17.3 KHz

(d) 12.6 KHz

This question was addressed to me by my college professor while I was bunking the class.

This question is from Problems of AM in division Amplitude Modulation of Analog Communications

Answer 1

The correct answer is (d) 12.6 KHz

To elaborate: Modulating Frequency (fm) = Vmax-Vmin, where,

Vmax = Maximum Amplitude of an amplitude modulated,

    Vmin = Minimum amplitude  of an amplitude modulated,

fm = 7KHz – 700Hz = 6.3KHz

Bandwidth = 2fm = 2 x 6.3 = 12.6 KHz.