fg_03_08.m

英文书《Digital Signal Processing with Examples in MATLAB》附带的MATLAB实例

% fg_03_08 - Fig. 3.8. zeros appended to x.
N1=32; N2=128;
x=[ones(1,N1/2),-ones(1,N1/2)];
y=[x,zeros(1,N2-N1)];
X=fft(x,N1);
Y=fft(x,N2);
% Plots.
sp_fig(1,8,6.6);
subplot(2,2,1);
axis([0 N1 -1.2 1.2]);
set(gca,'fontsize',16)
line(0:N1-1,x,'marker','x','color','r'); grid;
xlabel('n');
ylabel('x_n');
title('Original signal; N_1=32');

subplot(2,2,3);
axis([0 .55 0 25]);
set(gca,'fontsize',16)
line(0:1/N1:.5,abs(X(1:N1/2+1)),'marker','o','color','r'); grid;
xlabel('\nu (Hz-s)');
ylabel('|X_m|');

subplot(2,2,2);
axis([0 N2 -1.2 1.2]);
set(gca,'fontsize',16)
line(0:N2-1,y,'marker','x','color','b'); grid;
xlabel('n');
ylabel('y_n');
title('Signal with zeros appended; N_2=128');

subplot(2,2,4);
axis([0 .55 0 25]);
set(gca,'fontsize',16)
line(0:1/N2:.5,abs(Y(1:N2/2+1)),'marker','*','color','b'); grid;
h2=line(0:1/N1:.5,abs(Y(1:N2/N1:N2/2+1)),'marker','o','color','b');
set(h2,'linestyle','none');
xlabel('\nu (Hz-s)')
ylabel('|Y_m|');