% 第七章: 例 7.18
% 頻率采樣技術(shù): 高通, 最優(yōu)法 T1
%            ws=0.6pi, wp=0.8pi, Rp=1dB, As=50dB
%            M=33, T1 = 0.1095; T2 = 0.598;
M = 33; alpha = (M-1)/2; l = 0:M-1; wl = (2*pi/M)*l;
T1 = 0.1095; T2 = 0.598;
Hrs = [zeros(1,11),T1,T2,ones(1,8),T2,T1,zeros(1,10)];
Hdr = [0,0,1,1]; wdl = [0,0.6,0.8,1];
k1 = 0:floor((M-1)/2); k2 = floor((M-1)/2)+1:M-1;
angH = [-alpha*(2*pi)/M*k1, alpha*(2*pi)/M*(M-k2)];
H = Hrs.*exp(j*angH);
h = real(ifft(H,M));
[db,mag,pha,grd,w] = freqz_m(h,1);
[Hr,ww,a,L] = Hr_Type1(h);
subplot(1,1,1)
subplot(2,2,1);plot(wl(1:17)/pi,Hrs(1:17),'o',wdl,Hdr); 
axis([0,1,-0.1,1.1]); title('高通: M=33,T1=0.1095,T2=0.598')
xlabel(''); ylabel('Hr(k)')
set(gca,'XTickMode','manual','XTick',[0;.6;.8;1])
set(gca,'XTickLabelMode','manual','XTickLabels',[' 0';'.6';'.8';' 1'])
set(gca,'YTickMode','manual','YTick',[0,0.109,0.59,1]); grid
subplot(2,2,2); stem(l,h); axis([-1,M,-0.4,0.4])
title('脈沖響應(yīng)'); ylabel('h(n)');text(M+1,-0.4,'n')
subplot(2,2,3); plot(ww/pi,Hr,wl(1:17)/pi,Hrs(1:17),'o');
axis([0,1,-0.1,1.1]); title('振幅響應(yīng)')
xlabel('頻率（單位：pi）'); ylabel('Hr(w)')
set(gca,'XTickMode','manual','XTick',[0;.6;.8;1])
set(gca,'XTickLabelMode','manual','XTickLabels',[' 0';'.6';'.8';' 1'])
set(gca,'YTickMode','manual','YTick',[0,0.109,0.59,1]); grid
subplot(2,2,4);plot(w/pi,db); axis([0,1,-100,10]); grid
title('幅度響應(yīng)'); xlabel('頻率（單位：pi）');
ylabel('分貝數(shù)');
set(gca,'XTickMode','manual','XTick',[0;.6;.8;1])
set(gca,'XTickLabelMode','manual','XTickLabels',[' 0';'.6';'.8';' 1'])
set(gca,'YTickMode','Manual','YTick',[-50;0]);
set(gca,'YTickLabelMode','manual','YTickLabels',['50';' 0'])
%