% Chapter 7 Example 7.26%           Staircase filter design using PM algorithm%w1 = 0; w2 = 0.3*pi; delta1 = 0.01;w3 = 0.4*pi; w4 = 0.7*pi; delta2 = 0.005;w5 = 0.8*pi; w6 = pi; delta3 = 0.001;deltaH = max([delta1,delta2,delta3]); deltaL = min([delta1,delta2,delta3]);weights = [delta3/delta1 delta3/delta2 1]delta_f = min((w3-w2)/(2*pi), (w5-w3)/(2*pi))M = ceil((-20*log10(sqrt(delta1*delta2))-13)/(14.6*delta_f)+1)f = [0 w2/pi w3/pi w4/pi w5/pi 1]m = [1 1 0.5 0.5 0 0];h = remez(M-1,f,m,weights);[db,mag,pha,grd,w] = freqz_m(h,[1]);delta_w = 2*pi/1000;w1i=floor(w1/delta_w)+1; w2i = floor(w2/delta_w)+1;w3i=floor(w3/delta_w)+1; w4i = floor(w4/delta_w)+1;w5i=floor(w5/delta_w)+1; w6i = floor(w6/delta_w)+1;Asd = -max(db(w5i:w6i))% optimum value was found at M=49M = 49;h = remez(M-1,f,m,weights);[db,mag,pha,grd,w] = freqz_m(h,[1]);Asd = -max(db(w5i:w6i))[Hr,omega,P,L] = ampl_res(h);%% Plotsfigure(1); subplot(1,1,1)subplot(2,2,1); stem([0:1:M-1],h); title('Actual Impulse Response')axis([0,M-1,-0.1,0.6]); xlabel('n'); ylabel('h(n)')set(gca,'XTickMode','manual','XTick',[0,M-1])set(gca,'YTickMode','manual','YTick',[-0.1:0.1:0.6])subplot(2,2,2);plot(w/pi,db);title('Magnitude Response in dB');axis([0,1,-80,10]); xlabel('frequency in pi units'); ylabel('DECIBELS')set(gca,'XTickMode','manual','XTick',f)set(gca,'YTickMode','manual','YTick',[-60,0]);set(gca,'YTickLabelMode','manual','YTickLabels',['60';' 0']);gridsubplot(2,2,3);plot(omega/pi,Hr);title('Amplitude Response');axis([0 1 -0.1 1.1]); xlabel('frequency in pi units'); ylabel('Hr(w)')set(gca,'XTickMode','manual','XTick',f)set(gca,'YTickMode','manual','YTick',[0,0.5,1]);griddelta_w = 2*pi/1000; sp_edge = w5/delta_w+1;subplot(2,2,4); b1w = omega(w1i:w2i)/pi; b1e = (Hr(w1i:w2i)-m(1))*weights(1); b2w = omega(w3i:w4i)/pi; b2e = (Hr(w3i:w4i)-m(3))*weights(2); b3w = omega(w5i:w6i)/pi; b3e = (Hr(w5i:w6i)-m(5))*weights(3); plot(b1w,b1e,b2w,b2e,b3w,b3e);title('Weighted Error');axis([0,1,-delta3,delta3]);xlabel('frequency in pi units'); ylabel('Hr(w)')set(gca,'XTickMode','manual','XTick',f)set(gca,'YTickMode','manual','YTick',[-delta3,0,delta3]);grid