Fs=1e+11;
%t=0:1/Fs:.000000003;
%a=abs(simout);
%Hs=spectrum.welch;
%psd(Hs,a,'Fs',Fs)
%a=simout(11:1001);
Pxx = periodogram(simout);
Hpsd = dspdata.psd(Pxx,'Fs',Fs); 
%Hpsd = normalizefreq(Hpsd);
plot(Hpsd);