clear all
tau=50e-12;tdf=20*tau;nitd=9;
E_3=1/(nitd+1);EO_3=1;
K_3=tau*sqrt(tau*E_3/3/sqrt(pi/2));KO_3=tau*sqrt(tau*EO_3/3/sqrt(pi/2));
for itd=1:nitd;
    td(itd)=itd*tdf+round((10*(rand-.5)))*tau;
end;
it=0;
for t=-2e-10:1e-12:1e-8;
    it=it+1;
    yg3ds=0;
    for itd=1:nitd;
        yg3ds=yg3ds+K_3*(-2)/(tau^2)*(1-2*(t-td(itd))^2/tau^2)*exp(-(t-td(itd))^2/tau^2);
    end;
    y_g_3(it)=K_3*(-2)/(tau^2)*(1-2*t^2/tau^2)*exp(-t^2/tau^2)+yg3ds;
end,
figure (1);t=-2e-10:1e-12:1e-8;plot(t,y_g_3,'r');%hold on;plot(t,y_g_2,'b');hold on;plot(t,y_g_3,'g');
xlabel('Time, sec');ylabel('Amplitude');grid;

iif=0;
for f=0:1e8:2e10;
    iif=iif+1;
    Yg3ds=0;
    for itd=1:nitd;
        Yg3ds=Yg3ds+K_3*tau*sqrt(pi)*exp(-(pi*tau*f)^2)*(2*pi*f)^2*exp(-j*2*pi*f*td(itd));
    end;
    Y_G_3(iif)=K_3*tau*sqrt(pi)*exp(-(pi*tau*f)^2)*(2*pi*f)^2+Yg3ds;
    YO_G_3(iif)=KO_3*tau*sqrt(pi)*exp(-(pi*tau*f)^2)*(2*pi*f)^2;
end,

figure (3);f=0:1e8:2e10;plot(f,abs(Y_G_3),'b');hold on;plot(f,YO_G_3,'g')
legend('s(f)','Y_{g_3}(f)');
xlabel('Frequency, Hz');ylabel('Magnitude');grid;