A message signal of the form A cos(ωt) is sent by amplitude modulation using the carrier v0 sin(ω0 t). Which of the following represents the AM signal?

v0 sin(ω0 t) + (A/2) sin[(ω0 − ω)t] + (A/2) sin[(ω0 + ω)t]
v0 sin[ω0(1 + 0.01 A sinωt)]
v0 sinω0 t + A cosωt
(v0 + A) cosωt sinω0 t

Correct answer: v0 sin(ω0 t) + (A/2) sin[(ω0 − ω)t] + (A/2) sin[(ω0 + ω)t]

Solution

AM signal = (v0 + A cos wt) sin w0 t = v0 sin w0 t + (A/2) sin[(w0+w)t] + (A/2) sin[(w0-w)t], giving carrier plus two sidebands.

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