Question 3 (20 Marks 5+5+5+5) HINT: The stem() function in Matlab is useful to plotting functions which are defined m(t) is defined by m(t) = 10 cos (2t 400 t) +5 cos (2t 1 000 t) +2 cos (2x3000t) A. Plot the amplitude spectrum M(f) as a function of f for the message signal m(t) at discrete points Hint: For parts B, C, and D it is only required to plot the amplitude spectrum for f20 B. m(t) is the input to a DSB-FC modulator which is characterized by, s,s8-FC(t) = 2011 +17m (t))cos(2 105 t) Use Matlab to plot the amplitude spectrum, Sose-rc (f) where Sos-Fc (f)Sosa-rc(t) and s[.] is the Fourier Transform C. m(t) is the input to a DSB-SC modulator which is characterized by -02 ) Use Matlab to plot the amplitude spectrum. SDSB-sc (f). where SDSB-Sc (f)- and s[. is the Fourier Transform m(t) is the input to a SSB-USB modulator which is characterized by s(t)--Lm(t)+jrm(t)]cos(2 105t), where m(t) is the Hilbert Transform of m(t) Use Matlab to plot the amplitude spectrum, IS(f), where S(f)-s()] and - is the Fourier Transform Sose-sc (t)] D. 17