h=round(rand(1,10));
         hold off;
        bit=[];
        for n=1:2:length(h)-1;
            if h(n)==0 & h(n+1)==1
                se=[zeros(1,50) ones(1,50)];
            elseif h(n)==0 & h(n+1)==0
                se=[zeros(1,50) zeros(1,50)];
            elseif h(n)==1 & h(n+1)==0
                se=[ones(1,50) zeros(1,50)];
            elseif h(n)==1 & h(n+1)==1
                se=[ones(1,50) ones(1,50)];
            end
            bit=[bit se];
        end
        subplot(411)
        t=1/500:1/500:1;
        plot(t,bit,'LineWidth',1.5);grid on;
        axis([0 1 -1.5 1.5]);
        fc=30;
        fd=60;
        tx=0:0.1/100:1;
        a=sin(2*pi*fc*tx);
        subplot(412)
        plot(tx,a,'LineWidth',1.5);
        b=sin(2*pi*fd*tx);
        subplot(413)
        plot(tx,b,'LineWidth',1.5);
        n=1;
        subplot(414)
  while n<=length(h)
        if h(n)==0
            tx=(n-1)*0.1:0.1/100:n*0.1;
            p=(2)*sin(2*pi*fc*tx);
            plot(tx,p,'LineWidth',1.5);grid on;
            hold on;
        else 
            tx=(n-1)*0.1:0.1/100:n*0.1;
            p=(2)*sin(2*pi*fd*tx);
            plot(tx,p,'LineWidth',1.5);grid on;
            hold on;
        end
            n=n+1;
            end