Question

1. Consider a DSB-SC signal with noise passes through a demodulator shown below. ViC0) 2(0) но но 0) The input signal plus noise is v,(t)-5,() + n'(t) where 5,0): Am(1)cos2r/rt, m(1) cos 2π/J is the message signal with f-</м , carrier frequency is f> fe , and noise n' (r) has power spectral density function G,じ)= η . The local carrier is v,(1)s 2 cosZrw. The carrier filter is 1/(/)-4 for·s/ sf, + , and H(/):0 otherwise. The low-pass filter is H"(/)-2 for lflsfu, and H,U)-0 otherwise. (a) (10%) Draw H(/) and HBU). (b) (10%) Determine the signals si (1), s2(1), and s (1) at vi(1), v2(1), and v (1), respectively. (c) (10%) Draw power spectral density functions for noises ni(1), n2(1) and nd) at vi(), V2(), and y (t), respectively (d) (15%) Determine input SNR, output SNR, and figure of merit.

can you please solve this problem step by step, thank you!!

Answer 1

The input signal plus noise is v_I (t) = S_I (t) + n_I (t) s_I (t) = (t m (t) cos 2 pi f_t t_s m (t) = cos 2 pi f m t v_I (t) = s I (t) + n i (t) = a_m (t) cos 2 pi f c t + n I (t) = a cos 2 n f m t + cos 2 pi f c t + ni (t) = a/2 [cos 2 pi (f c + f m) t + cos 2 pi (f c - f m)t] + n I (t) (f) = { 4 0 f lessthanorequalto f lessthanorequalto f c f m otherwise h_b (f