psds.m

《Home Networking Basis》（《家庭网络基础》）的配套MATLAB源代码。包括了以太网和无线以太网等模型。

%f=[0:1000]/1000*4e8;
f=[0:1000]/1000*16e8;
%k=0.2^2/110/0.001;
k=0.8^2/110/0.001;
%T1=1/98.304e6;
T1=1/491.52e6;
T2=T1/2;
T3=T2/2;
PSDs1=10*log10(k/T1*((sin(pi*f*T1)).^2./(pi*f).^2));
PSDs2=10*log10(k/T2*((sin(pi*f*T2)).^2./(pi*f).^2));
PSDs3=10*log10(k/T3*((sin(pi*f*T3)).^2./(pi*f).^2));
for i=1:1000
    if PSDs1(i)<-140
        PSDs1(i)=-140;
    end
    if PSDs2(i)<-140
        PSDs2(i)=-140;
    end
    if PSDs3(i)<-140
        PSDs3(i)=-140;
    end
end
plot(f,PSDs1,f,PSDs2,f,PSDs3);
grid
xlabel('Frequency (Hz)')
ylabel('PSD (dBm/Hz)')
%gtext('S100')
%gtext('S200')
%gtext('S400')
gtext('S400b')
gtext('S800b')
gtext('S1600b')