数字信号处理实验_matlab版_用双线性变换法设计iir数字滤波器

,ad) [H,w]=freqz(bd,ad); dbH=20*log10((abs(H)+eps)/max(abs(H))); subplot(2,2,1),plot(w/pi,abs(H)); ylabel( '|H|' );title( ' 幅度响应' );axis([0,1,0,1.1]); set(gca, 'XTickMode' , 'manual' , 'XTick' ,[0,0.25,0.4,1]); set(gca, 'YTickMode' , 'manual' , 'YTick' ,[0,Attn,ripple,1]);grid subplot(2,2,2),plot(w/pi,angle(H)/pi); ylabel( '\phi' );title( ' 相位响应' );axis([0,1,-1,1]); set(gca, 'XTickMode' , 'manual' , 'XTick' ,[0,0.25,0.4,1]); set(gca, 'YTickMode' , 'manual' , 'YTick' ,[-1,0,1]);grid subplot(2,2,3),plot(w/pi,dbH);title( ' 幅度响应(dB)' ); ylabel( 'dB' );xlabel( ' 频率' );axis([0,1,-40,5]); set(gca, 'XTickMode' , 'manual' , 'XTick' ,[0,0.25,0.4,1]); set(gca, 'YTickMode' , 'manual' , 'YTick' ,[-50,-15,-1,0]);grid subplot(2,2,4),zplane(bd,ad); axis([-1.1,1.1,-1.1,1.1]);title( ' 零极图' ); 运行结果如图 1-1 所示。