fig724.m

高西全2009年最新版<数字信号处理>源码程序

%《数字信号处理--原理、实现及应用》第六章 图7.2.1绘图程序:fig721.m
% 电子工业出版社出版  高西全  丁玉美  阔永红合著 2006年8月
close all;
wc=1/4;N=14;alph=(N-1)/2;
wrn=boxcar(N);WRg=fft(wrn,512);
hn=fir1(N-1,wc,boxcar(N));Hg=fft(hn,512)
Hk=fft(hn,512);
w=(0:511)*2*pi/512;
subplot(3,3,1),plot(w/pi,20*log10(abs(WRg)/max(abs(WRg))))
xlabel('ω/π');ylabel('W_R_g(\omega)/dB')
title('(a) N=14')
axis([0,1,-40,5])
grid on;
subplot(3,3,7),plot(w/pi,20*log10(abs(Hg)/max(abs(Hg))))
xlabel('ω/π');ylabel('H_g(\omega)/dB')
title('(d) N=14')
axis([0,1,-60,5])
grid on;
N=20;alph=(N-1)/2;
wrn=boxcar(N);WRg=fft(wrn,512);
hn=fir1(N-1,wc,boxcar(N));Hg=fft(hn,512)
Hk=fft(hn,512);
w=(0:511)*2*pi/512;
subplot(3,3,2),plot(w/pi,20*log10(abs(WRg)/max(abs(WRg))))
xlabel('ω/π');
title('(b) N=20')
axis([0,1,-40,5])
grid on;
subplot(3,3,8),plot(w/pi,20*log10(abs(Hg)/max(abs(Hg))))
xlabel('ω/π');
title('(e) N=20')
axis([0,1,-60,5])
grid on;
N=36;alph=(N-1)/2;
wrn=boxcar(N);WRg=fft(wrn,512);
hn=fir1(N-1,wc,boxcar(N));Hg=fft(hn,512)
Hk=fft(hn,512);
w=(0:511)*2*pi/512;
subplot(3,3,3),plot(w/pi,20*log10(abs(WRg)/max(abs(WRg))))
xlabel('ω/π');
title('(c) N=36')
axis([0,1,-40,5])
grid on;
subplot(3,3,9),plot(w/pi,20*log10(abs(Hg)/max(abs(Hg))))
xlabel('ω/π');
title('(f) N=36')
axis([0,1,-60,5])
grid on;