fg_06_06.m

英文书《Digital Signal Processing with Examples in MATLAB》附带的MATLAB实例

% fg_06_06  Analog Chebyshev gain.
wc=1; N=500; w1=10; dB0=-45; dBs=-40;
L=[2 4 6];
clr=['r' 'g' 'b'];
xt=[2.2 1.55 0.7];
yt=[-13 -19 -33];
w=linspace(0,w1,N);
sp_fig(1,8.5,3.5);
axis([0 w1 dB0 0]);
set(gca,'fontsize',16);
for plt=1:length(L),
   ws=wc*cosh((6.02-dBs)/(8.69*L(plt)));
   VL0=cosh(L(plt)*acosh(ws/wc));
   VL=cosh(L(plt)*acosh(ws./max(1.e-20,w)));
   P=1./(1+(VL0^2)./(VL.^2));
   dB=10*log10(max(10^(dB0/10),P));
   line(w,dB,'color',clr(plt),'linewidth',1.5);
   h=text(xt(plt),yt(plt),['L=',num2str(L(plt))]);
   set(h,'fontsize',16);
end
grid;
set(gca,'xtick',[0:1:10]);
xlabel('Frequency (rad/s)');
ylabel('Chebyshev power gain (dB)');