Low-pass-filter-simulation-.rar_Chebyshev

wp1 = 0.4*pi; wp2 = 0.6*pi; ws1 = 0.3*pi; ws2 = 0.7*pi; tr_width = min((wp1-ws1),(ws2-wp2)) tr_width =0.3142 M = ceil(6.2*pi/tr_width) + 1 M = 63 n=[0:1:M-1]; wc1 = (ws1+wp1)/2; wc2 = (wp2+ws2)/2; wc=[wc1/pi,wc2/pi]; window= hanning(M); [h1,w]=freqz(window,1); figure(1); subplot(2,1,1) stem(window); axis([0 60 0 1.2]); grid; xlabel('n'); title('Hanning窗函数'); subplot(2,1,2) plot(w/pi,20*log(abs(h1)/abs(h1(1)))); axis([0 1 -350 0]); grid; xlabel('w/\pi'); ylabel('幅度(dB)'); title('Hanning窗函数的频谱'); hn = fir1(M-1,wc, hanning (M)); [h2,w]=freqz(hn,1,512); figure(2); subplot(2,1,1) stem(n,hn); axis([0 60 -0.25 0.25]); grid; xlabel('n'); ylabel('h(n)'); title('Hanning窗函数的单位脉冲响应'); subplot(2,1,2) plot(w/pi,20*log(abs(h2)/abs(h2(1)))); grid; xlabel('w/\pi'); ylabel('幅度(dB)'); figure(3); phase=angle(h1); plot(phase); axis([1 pi -1 0]); xlabel('w/\pi'); ylabel('线性相位'); title('Hanning窗函数相位特性曲线')