ex0826.asv

数字信号处理（机械工业出版社）的源码

% Chapter 08: Example 8.26 Design a filter
Fs=1000;
b=remez(21,[0 1],[0 pi*Fs],'differentiator');
bb=remez(20,[0 0.9],[0 0.9*pi*Fs],'differentiator');
[h,w]=freqz(b,1,512,2);
[hh,ww]=freqz(bb,1,512,2);
z=w*pi*Fs;
subplot(211); plot(w,abs(h),w,z,':'); grid on
title('Odd filter order ');
xlabel('Normalized Frequency'); ylabel('magnitude(dB)');
subplot(212); plot(ww,abs(hh),w,z,':'); grid on
title('Even filter order');
xlabel('Normalized Frequency'); ylabel('magnitude(dB)');