q let at 1 maxt and xt cos 2pifmt fm ltlt fc

Question

Q. Let a(t) = [1 + m_Ax(t)] and x(t) = cos 2πf_mt, f_m << f_c, and x_c(t) = A(t) cos 2πfct .

(a) With m_A =1, sketch one full period of the AM wave and draw the envelope by connecting the positive peaks of x_c(t).

(b) Repeat part (a) with mA = 2, and notice that the carrier is overmodulated and the envelope does not have the same shape as x(t).