ex0312.m

数字信号处理（机械工业出版社）的源码

% Chapter 3 : Example 3.19
%             Reconstruction using sinc function
%
% Discrete-time Signal x1(n)
Ts1 = 0.0002; Fs1 = 1/Ts1; n1 = -25:1:25; nTs1 = n1*Ts1;
x1 = exp(-1000*abs(nTs1));
% Discrete-time Signal x2(n)
Ts2 = 0.001; Fs2 = 1/Ts2; n2 = -5:1:5; nTs2 = n2*Ts2;
x2 = exp(-1000*abs(nTs2));
% Analog Signal reconstruction for x1(n)
Dt = 0.00005;
t = -0.005:Dt:0.005;
xa1 = x1 * sinc(Fs1*(ones(length(nTs1),1)*t-nTs1'*ones(1,length(t))));
% Analog Signal reconstruction for x2(n)
xa2 = x2 * sinc(Fs2*(ones(length(nTs2),1)*t-nTs2'*ones(1,length(t))));
% check
error1 = max(abs(xa1 - exp(-1000*abs(t))))
error2 = max(abs(xa2 - exp(-1000*abs(t))))
% Plots
subplot(2,1,1);plot(t*1000,xa1);hold on
stem(nTs1*1000,x1); hold off
xlabel('t in msec.'); ylabel('xa1(t)')
title('Reconstructed Signal from x1(n) using sinc function');
subplot(2,1,2);plot(t*1000,xa2);hold on
stem(nTs2*1000,x2); hold off
xlabel('t in msec.'); ylabel('xa2(t)')
title('Reconstructed Signal from x2(n) using sinc function');