MatLab Code Used:

%AM Modulation; clear; Ac=5; Am=5; fc=10000; fm=1000; t=0:0.00001:0.003; m=Am*cos(2*pi*fm*t); c=Ac*cos(2*pi*fc*t); mi = Am/Ac; s=Ac*(1+mi*cos(2*pi*fm*t)).*cos(2*pi*fc*t); subplot(2,2,1); plot(t,s); xlabel('time'); ylabel('amplitude'); title('AM modulation'); subplot(2,2,4); yyaxis left; plot(t,m); yyaxis right; plot(t,s); title('combined message and AM signal'); xlabel('time'); ylabel('amplitude');

%FM kvco=1000; beta=(kvco*Am)/fm; sFM=Ac*cos((2*pi*fc*t)+beta*sin(2*pi*fm*t)); subplot(2,2,2); plot(t,sFM); xlabel('time'); ylabel('amplitude'); title('FM modulation');

%combined FM and m(t) plot subplot(2,2,3); yyaxis left; plot(t,m); yyaxis right; plot(t,sFM); title('combined message and FM signal'); xlabel('time'); ylabel('amplitude');

1) Change the message amplitude to 1, and plot.

1) Select the statement that best describes the resultant wave forms. a. Regarding FM modulation, with Am=1, the FM Index becomes very small, resulting in a modulated carrier signal that barely changes as the message changes. b. Regarding AM modulation, the AM index is between 0 and 1, and therefore, it can be seen that the AM modulated carrier signal represents the message. c. Both statements are correct d. Neither statement is correct.

2) Change the message amplitude to 10, and answer the following questions. 2) Select the statement that best describes your observation. a. The FM modulated carrier signal appears to change with the message b. The AM modulated carrier shows distortion since the AM index is >1 c. In both the AM and FM cases, Am = 10v and Ac = 5v d. All of the statements are correct

Figure 1 File Edit View Tools Desktop Window Help AM modulation FM modulation 10 -10 -5 0.5 1.5 time 0.5 1.5 time 2.5 2.5 x 10 x 10 combined message and FM signal combined message and AM signal 10 0.5 1.5 2.5 0.5 1.5 2.5 time x 10 time x 10 Figure 1 File Edit View Tools Desktop Window Help AM modulation FM modulation 10 -10 -5 0.5 1.5 time 0.5 1.5 time 2.5 2.5 x 10 x 10 combined message and FM signal combined message and AM signal 10 0.5 1.5 2.5 0.5 1.5 2.5 time x 10 time x 10