?? ampreshn.m
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% Chapter 7: Hanning Window Amplitude Response%M = 45; alpha = (M-1)/2;n = -alpha:alpha;w = (hanning(M))'; sumw = sum(w);N = 1000; omega = (2*pi/N)*[-N/2:N/2];Wr = real(w*(exp(-j*n'*omega)));db = 20*log10(abs(Wr)/max(Wr));IntWr = cumsum(Wr);Intdb = 20*log10(abs(IntWr)/N);l = min(find(Intdb > -44)); % Use this and the nextk = (N/2+1) - 467; % when logic does not work%k = (N/2+1) - (min(find(Intdb > -44))+l-1); % correcttr_width = 2*k*2*M/N, %actual transition width in pi/M unitsomega1 = -(tr_width/2)/M; omega2 = (tr_width/2)/M;%% plotssubplot(1,1,1)subplot(2,2,1); stem(n,w);axis([-(alpha+8),(alpha+8),-0.1,1.1]);set(gca,'YTickMode','manual','YTick',[0,1])set(gca,'XTickMode','manual','XTick',[-22,0,22]);set(gca,'XTickLabelMode','manual','XTickLabels',[' 0';'22';'45']);title('Hanning Window : M=45')xlabel('n'); ylabel('w(n)')subplot(2,2,3); plot(omega/pi,Wr);axis([-1,1,-2,sumw+5]);set(gca,'YTickMode','manual','YTick',[0,sumw])set(gca,'XTickMode','manual','XTick',[-1,0,1]); gridtitle('Amplitude Response')xlabel('frequency in pi units'); ylabel('Wr')subplot(2,2,2); plot(omega/pi,db);axis([-1,1,-60,10]);set(gca,'YTickMode','manual','YTick',[-60,-32,0])set(gca,'YTickLabelMode','manual','YTickLabels',['60';'32';' 0'])set(gca,'XTickMode','manual','XTick',[-1,0,1]);gridtitle('Amplitude Response in dB')xlabel('frequency in pi units'); ylabel('Decibels')subplot(2,2,4); plot(omega/pi,Intdb);axis([-1,1,-60,10]);set(gca,'YTickMode','manual','YTick',[-60,-44,0])set(gca,'YTickLabelMode','manual','YTickLabels',['60';'44';' 0'])set(gca,'XTickMode','manual','XTick',[-1;omega1;omega2;1]);gridset(gca,'XTickLabelMode','manual','XTickLabels',['-1';' ';' ';' 1'])title('Accumulated Amplitude Response')xlabel('frequency in pi units'); ylabel('Decibels')text(omega2,5,'Width=(6.2)*pi/M')?? 快捷鍵說明
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