4.2-2 Consider the following base band message signals (i) m (t) = sin 150n t; (i) m2(t)2 exp(-21)u(1): (iii) cos 20071 + rect(100r): (iv) m(t) = 50exp(-100|r) sgn(): and (v)m(1)

= 500exp(-100|1-0.5). For each of the five message signals, (a) sketch the spectrum of m(t); (b) sketch the spectrum of the DSB-SC signal 2m(t) cos 2000nt; (c) identify the USB and the LSB spectra.