www.gusucode.com > signal 案例源码程序 matlab代码 > signal/FIRLowpassFilterExample.m
%% FIR Lowpass Filter % Design a 30th-order lowpass filter with a normalized cutoff frequency of % $0.6\pi$ rad/sample. Plot the ideal frequency response overlaid with % the actual frequency response. %% f = [0 0.6 0.6 1]; m = [1 1 0 0]; b1 = fir2(30,f,m); [h1,w] = freqz(b1,1); plot(f,m,w/pi,abs(h1)) xlabel('\omega / \pi') lgs = {'Ideal','fir2 default'}; legend(lgs) %% % Redesign the filter using a 64-point interpolation grid. b2 = fir2(30,f,m,64); h2 = freqz(b2,1); hold on plot(w/pi,abs(h2)) lgs{3} = 'npt = 64'; legend(lgs) %% % Redesign the filter using the 64-point interpolation grid and a 13-point % interval around the cutoff frequency. b3 = fir2(30,f,m,64,13); h3 = freqz(b3,1); plot(w/pi,abs(h3)) lgs{4} = 'lap = 13'; legend(lgs)