代码:
M = 25; alpha = (M-1)/2; n = [0:1:M-1]; hd = (2/pi) * ( (sin( (pi/2)*(n-alpha) ).^2)./(n-alpha) ); hd(alpha+1) = 0; w_han = (hann(M))'; h = hd .* w_han; [Hr, w, P, L] = Hr_Type3(h); P L %Plot figure('NumberTitle', 'off', 'Name', 'Exameple 7.13') set(gcf,'Color','white'); subplot(2,2,1); stem(n, hd); axis([-1 M -1.2 1.2]); grid on; xlabel('n'); ylabel('hd(n)'); title('Ideal Impulse Response'); subplot(2,2,2); stem(n, w_han); axis([-1 M 0 1.2]); grid on; xlabel('n'); ylabel('w(n)'); title('Hann Window'); subplot(2,2,3); stem(n, h); axis([-1 M -1.2 1.2]); grid on; xlabel('n'); ylabel('h(n)'); title('Actual Impulse Response'); w = w'; Hr = Hr'; w = [-fliplr(w), w(2:501)]; Hr = [-fliplr(Hr), Hr(2:501)]; subplot(2,2,4); plot(w/pi, Hr); axis([-1 1 -1.1 1.1]); grid on; xlabel('frequency in pi units'); ylabel('Hr'); title('Amplitude Response');
运行结果:
注意:振幅谱的频率范围是从-π到π。