hello every one
i have a problem with the mash 111 SDM attached it's model and the m code to plot it's power spectral density ,... BUT i don't know what is the problem with the code i can't find the 60 db slop as it should be !!
can any one help me please ?!

here is a copy of my simple code using the pwelch function.

N=length(A);
fs=10^(3);
[Pxx,fx] = pwelch(A,hann(2^16),0,2^(18),fs);
plot(fx,10*log10(Pxx));
grid on

is there any thing wrong in my simulink model or my code ?!
if there is ,... so please any suggestions ?
thanks everyone !