%要求设计一butterworth 低通数字滤波器，wp=30hz，ws=40hz，rp=0.5，rs=40，fs=100hz。 >> wp=30;ws=40;rp=0.5;rs=40;fs=100; >> wp=30*2*pi;ws=40*2*pi; >> [n,wn]=buttord(wp,ws,rp,rs,'s'); >> [z,p,k]=buttap(n); >> [num,den]=zp2tf(z,p,k); >> [num1,den1]=impinvar(num,den); Warning: The output is not correct/robust. Coeffs of B(s)/A(s) are real, but B(z)/A(z) has complex coeffs. Probable cause is rooting of high-order repeated poles in A(s). > In impinvar at 124 >> [num2,den2]=bilinear(num,den,100); >> [h,w]=freqz(num1,den1); >> [h1,w1]=freqz(num2,den2); >> subplot(1,2,1); >> plot(w*fs/(2*pi),abs(h)); >> subplot(1,2,2); >> plot(w1*fs/(2*pi),abs(h1)); >> figure(1); >> subplot(1,2,1); >> zplane(num1,den1); >> subplot(1,2,2); >> zplane(num2,den2); %要求设计一 chebyshev1 低通数字滤波器，wp=30hz，ws=40hz，rp=0.5，rs=40，fs=100hz. >> wp=30;ws=40;rp=0.5;rs=40;fs=100; >> wp=30*2*pi;ws=40*2*pi; >> [n,wn]=cheb1ord(wp,ws,rp,rs,'s'); >> [z,p,k]=cheb1ap(n,rp); >> [num,den]=zp2tf(z,p,k); [num1,den1]=impinvar(num,den); >> [num2,den2]=bilinear(num,den,100); [h,w]=freqz(num1,den1); [h1,w1]=freqz(num2,den2); subplot(1,2,1); plot(w*fs/(2*pi),abs(h)); subplot(1,2,2); plot(w1*fs/(2*pi),abs(h1)); figure(2); subplot(1,2,1); zplane(num1,den1); subplot(1,2,2); zplane(num2,den2); %要求设计一 chebyshev2 低通数字滤波器，wp=30hz，ws=40hz，rp=0.5，rs=40，fs=100hz. wp=30;ws=40;rp=0.5;rs=40;fs=100; wp=30*2*pi;ws=40*2*pi; [n,wn]=cheb2ord(wp,ws,rp,rs,'s'); [z,p,k]=cheb2ap(n,rs); [num,den]=zp2tf(z,p,k); [num1,den1]=impinvar(num,den); [num2,den2]=bilinear(num,den,100); [h,w]=freqz(num1,den1); [h1,w1]=freqz(num2,den2); subplot(1,2,1); plot(w*fs/(2*pi),abs(h)); subplot(1,2,2); plot(w1*fs/(2*pi),abs(h1)); figure(2); subplot(1,2,1); zplane(num1,den1); subplot(1,2,2); zplane(num2,den2); Rp，rs 增大，chebyshev2 的幅频响应图会好 wp=500;ws=600;rp=1;rs=60;fs=1000; wp=500*2*pi;ws=600*2*pi; 不明白的...
