cic.m

个人编写的关于积梳状滤波器的程序,用于抽取和插值时防止信号失真.

clear all;
N3=16;a=0.03;b=0.4;N1 = 16-b;N2=16+b;n1 =2 ;n2 =N1/n1;n3=2;n4=N2/n3;n5=2;n6=N3/n5;k=1;l=2;% Define the filter parameters
w = linspace(0,pi,1024); % Set the frequency in radians
% Calculate the frequency response of the filter
%h =(1/(r*m)*sin(r*m*w/2)./sin(w/2)).^(n1);
%H=3*h.^2-2*h.^3;
y1=(1/n1)*(sin(w*n1/2)./sin(w/2));
y2=(1/n2)*(sin(w*N1/2)./sin(w*n1/2));
y3=(1/n3)*(sin(w*n3/2)./sin(w/2));
y4=(1/n4)*(sin(w*N2/2)./sin(w*n3/2));
y5=(1/n5)*(sin(w*n5/2)./sin(w/2));
y6=(1/n6)*(sin(w*N3/2)./sin(w*n5/2));
y7=y2.*y4.*y6;
y8=3*y7.^(2*k)-2*y7.^(3*k);
x=(y1.^(l)).*(y3.^(l)).*(y5.^(l)).*y8;
%plot(w/pi,20*log10(abs(h)),'k:'); hold on;

plot(w/pi,20*log10(abs(x))); hold on;
xlabel('(\times\pi rad/sample)');
ylabel('Magnitude (dB)');
m1=2;m2=8;m=m1*m2;k1=1;k2=4;% Define the filter parameters
 % Set the frequency in radians
% Calculate the frequency response of the filter
%h =(1/(r*m)*sin(r*m*w/2)./sin(w/2)).^(n1);
%plot(w/pi,20*log10(abs(h)),'k:'); hold on;
h1=(1/m2)*(sin(w*m/2)./sin(w*m1/2));
h2=(1/m1)*(sin(w*m1/2)./sin(w/2));
h3=(1/(m2.^2))*((sin((w+a)*m/2).*sin((w-a)*m/2))./(sin((w+a)*m1/2).*sin((w-a)*m1/2)));
h4=3*(h1.^(2*k1))-2*(h1.^(3*k1));
h5=h2.^(k2);
h6=h3.*h4.*h5;
h7=(1/(m.^3))*((sin(w*m/2))./(sin(w/2))).*((sin((w+a)*m/2).*sin((w-a)*m/2))./(sin((w+a)/2).*sin((w-a)/2)));
%h8=h7.*h5;
%plot(w/pi,20*log10(abs(h3)),'k:'); hold on;
plot(w/pi,20*log10(abs(h6)),'k:');
axis([0,1,-300,0.01]);
xlabel('(\times\pi rad/sample)');
ylabel('Magnitude (dB)');