% 第七章: 例7.11 帶阻濾波器設計 - 凱澤窗
%
M = 45; As = 60; n=[0:1:M-1];
beta = 0.1102*(As-8.7)
w_kai = (kaiser(M,beta))';
wc1 = pi/3; wc2 = 2*pi/3;
hd = ideal_lp(wc1,M) + ideal_lp(pi,M) - ideal_lp(wc2,M);
h = hd .* w_kai;
[db,mag,pha,grd,w] = freqz_m(h,[1]);
%
subplot(1,1,1)
subplot(2,1,2);plot(w/pi,db);
title('幅度響應（單位：dB）');grid;
xlabel('頻率（單位： pi）'); ylabel('分貝數')
axis([0 1 -100 10]); 
set(gca,'XTickMode','manual','XTick',[0;0.333;0.667;1])
set(gca,'XTickLabelMode','manual',...
    'XTickLabels',[' 0 ';'1/3';'2/3';' 1 '])
set(gca,'YTickMode','manual','YTick',[-60,0])
set(gca,'YTickLabelMode','manual','YTickLabels',['60';' 0'])
%pause;
%print -deps2 ex071101.eps
%
M = 45; As = 60; n=[0:1:M-1];
beta = 0.1102*(As-8.7)+.3
w_kai = (kaiser(M,beta))';
wc1 = pi/3; wc2 = 2*pi/3;
hd = ideal_lp(wc1,M) + ideal_lp(pi,M) - ideal_lp(wc2,M);
h = hd .* w_kai;
[db,mag,pha,grd,w] = freqz_m(h,[1]);
%
% plots
subplot(1,1,1);
subplot(2,2,1); stem(n,hd); title('理想脈沖響應')
axis([-1 M -0.2 0.8]); ylabel('hd(n)');text(M+1,-0.2,'n')
subplot(2,2,2); stem(n,w_kai);title('凱澤窗')
axis([-1 M 0 1.1]);  ylabel('w(n)');text(M+1,0,'n')
subplot(2,2,3); stem(n,h);title('實際脈沖響應')
axis([-1 M -0.2 0.8]); xlabel('n'); ylabel('h(n)')
subplot(2,2,4);plot(w/pi,db);
title('幅度響應（單位：db）');grid;
xlabel('頻率（單位： pi ）'); ylabel('分貝數')
axis([0 1 -110 10]); 
set(gca,'XTickMode','manual','XTick',[0;0.333;0.667;1])
set(gca,'XTickLabelMode','manual',...
    'XTickLabels',[' 0 ';'1/3';'2/3';' 1 '])
set(gca,'YTickMode','manual','YTick',[-60,0])
set(gca,'YTickLabelMode','manual','YTickLabels',['60';' 0'])
%print -deps2 ex071102.eps