Ejemplo 1: t= 0:1/1000:1; // declare time intervalAc = 9; // amplitude of carrier signalAm = 4; // amplitude of modulating signalfc = 100; // carrier frequencyfm = 50; // modulating frequency//Carrier signalVc = Ac *cos (((2*%pi)*fc)*t);//Modulating signal Vm = Am * sin (((2*%pi)*fm)*t);//Frequency modulation signal m = 2; //modulation index Vfm = Ac*cos(((( 2*%pi)*fc)*t)+m*sin(((2*%pi)*fm)*t));// plot signalsubplot (311);plot (t, Vm)title (Modulating signal)subplot (312);plot (t,Vc);title (Carrier signal)subplot (313);plot (t,Vfm)title (Frequency modulating signal)Ejemplo 2:N=1024;//Number of pointsfs=4096;//Sampling frequencyt=(0:N-1)/fs;//Time Vectorfm=50;//Message Freq 1Em=3;//Amplitude of modulating signalm=3;//Modulating Indexfc=300; //Carrier frequencyVm=Em*cos(2*%pi*fm*t);//Modulating signal//Frecuency Modulation (FM)Vfm=cos(2*%pi*fc*t+Vm);Vf=(2/N)*abs(mtlb_fft(Vfm,2048))*1024;//Frequency modulation in time domainf=(fs*(0:N/2))/N;subplot(2,1,1);//Time domain plotplot(t(1:N/2),Vfm(1:N/2),t(1:N/2),Vm(1:N/2),"r");title("Time Domain Representation");xlabel("Time");ylabel("Modulated signal");subplot(2,1,2); //Frequency Domain Plotplot(f(1:256),Vf(1:256));title("Frequency Domain Representation");xlabel("Frequency (Hz)");ylabel("Spectral Magnitude");Ejemplo 3:fs = 1000; // sampling frequencydelt = 1/fs; //sampling incrementt = 0:delt:1-delt; //time vectorN=1024 // number of pointsfn = (0:N/2)*(fs/N); // frequency vector for plotm1 = 2*cos(((2*%pi)*50)*t); // modulation signal 1m2 = 2*cos(((2*%pi)*50)*t) + 1*cos(((2*%pi)*5)*t); //modulation signal 2xc1 = sin((((2*%pi)*250)*t)+m1); // modulated carrier 1xc2 = sin((((2*%pi)*250)*t)+m2); // modulated carrier 2asxc1 = (2/N)*abs(fft(xc1)); // amplitude spectrum 1asxc2 = (2/N)*abs(fft(xc2)); //amplitude spectrum 2ampspec1 = asxc1(1:((N/2)+1)); // positive frequency portion 1ampspec2 = asxc2(1:((N/2)+1)); // positive frequency portion 2 subplot(211)plot2d(fn,ampspec1)xlabel('Frequency - Hz');ylabel('Amplitude');subplot(212)plot(fn, ampspec2, 'k');xlabel('Frequency - Hz');ylabel('Amplitude');