fir_demo.m

一个采用Matlab编写的设计FIR滤波器的教程和源代码

load firdata

figure;freqz(B1,1);
title('42 order lowpass,f0=0.3,my design');
figure;freqz(C1,1);
title('42 order lowpass,f0=0.3,gremez design');

figure;freqz(B2,1);
title('42 orders highpass,f0=0.3,my design');
figure;freqz(C2,1);
title('42 orders highpass,f0=0.3,gremez design');

figure;freqz(B3,1);
title('40 orders bandpass,[0.3,0.7],my design');
figure;freqz(C3,1);
title('40 orders bandpass,[0.3,0.7],gremez design');

figure;freqz(B4,1);
title('40 orders bandblock,[0.3,0.7],my design');
figure;freqz(C4,1);
title('40 orders bandblock,[0.3,0.7],gremez design');

figure;freqz(B5,1);
title('9 orders hilbert,my design');
figure;freqz(C5,1);
title('9 orders hilbert,gremez design');

figure;freqz(B6,1);[H,W] = freqz(B6,1);plot(W/pi,abs(H));
title('60 orders sidestep-shape,A=1 at [0.2,0.4],2 at [0.4,0.6],3 at [0.6,0.8],my design');
figure;freqz(C6,1);[H,W] = freqz(C6,1);plot(W/pi,abs(H));
title('60 orders sidestep-shape,A=1 at [0.2,0.4],2 at [0.4,0.6],3 at [0.6,0.8],gremez design');

figure;freqz(B7,1);[H,W] = freqz(B7,1);plot(W/pi,abs(H));
f=[0:0.01:1];
hold on;plot(f,1-cos(f*pi*2),'r');hold off;
title('10 orders rising cos shape,my design,red curve is ideal shape');
figure;freqz(C7,1);[H,W] = freqz(C7,1);plot(W/pi,abs(H));
hold on;plot(f,1-cos(f*pi*2),'r');hold off;
title('10 orders rising cos shape,gremez design,red curve is ideal shape');

figure;freqz(B8,1);[H,W] = freqz(B8,1);plot(W/pi,abs(H));
f=[0.01:0.01:1];a=[linspace(0,1,50),linspace(1,0,50)];
hold on;plot(f,a,'r');hold off;
title('40 orders triangle shape,my design,red curve is ideal shape');
figure;freqz(C8,1);[H,W] = freqz(C8,1);plot(W/pi,abs(H));
hold on;plot(f,a,'r');hold off;
title('40 orders triangle shape,gremez design,red curve is ideal shape');

figure;freqz(B9,1);[H,W] = freqz(B9,1);plot(W/pi,abs(H));
f = [0.001:0.001:1];
a = [linspace(0,1,100),linspace(1,0,100)];
a = [a a a a a];
hold on;plot(f,a,'r');hold off;
title('80 orders saw-shape,my design,red curve is ideal shape');
figure;freqz(C9,1);[H,W] = freqz(C9,1);plot(W/pi,abs(H));
hold on;plot(f,a,'r');hold off;
title('80 orders saw-shape,gremez design,red curve is ideal shape');

figure;freqz(B10,1);[H,W] = freqz(B10,1);plot(W/pi,abs(H));
axis([0,1,0,0.5]);
title('120 orders, a big bowl upside down! my design');
figure;freqz(C10,1);[H,W] = freqz(C10,1);plot(W/pi,abs(H));
axis([0,1,0,0.5]);
title('120 orders, a big bowl upside down! gremez design');
f = [0.01:0.01:1];
temp = linspace(0,0.25,25);
temp = sqrt(0.25^2-(0.25-temp).^2);
A = [zeros(1,12),temp,0.3*ones(1,25),fliplr(temp),zeros(1,13)];   %two bands pass filter design
figure;plot(f,A,'r');title('a standard and beautiful big bowl! ^_^');
axis([0,1,0,0.5]);