%  Gause信道容量 2007-6-4
%  CASE1:W=3000Hz,P/N:-20dB--30dB  繪圖 C vs P/N
%  CASE2:P/N=25dB, 繪圖 C vs W 
%  Both,when P/N or W trend to 0,C go to 0
%  But, when P/N or W trend to infinite, CASE1 is infinite,CASE2 is going
%  to a limit lg2(e)*P/N=1/ln2 *P/N=104427*P/N

echo on
pn0_db=[-20:0.1:30];
pn0=10.^(pn0_db/10);
capacity=3000.*log2(1+pn0/3000);
pause
clf
semilogx(pn0,capacity)
title('高斯信道容量與信噪比')
xlabel('P/N')
ylabel('Capacity(bits/s)')

clear
w=[1:10,12:2:100,105:5:500,510:10:5000,5025:25:20000,20050:50:100000];
pn0_db=25;
pn0=10.^(pn0_db/10);
capacity=w.*log2(1+pn0./w);
pause
clf
semilogx(w,capacity)
title('高斯信道容量與帶寬')
xlabel('BandWidth(Hz)')
ylabel('Capacity(bits/s)')