% Chapter 3 : Example 3.19
%             Reconstruction using sinc function
%
% Discrete-time Signal x1(n)
Ts = 0.0002; Fs = 1/Ts; n = -25:1:25; nTs = n*Ts;
x = exp(-1000*abs(nTs));
% Analog Signal reconstruction
Dt = 0.00005;
t = -0.005:Dt:0.005;
xa = x * sinc(Fs*(ones(length(nTs),1)*t-nTs'*ones(1,length(t))));
% check
error = max(abs(xa - exp(-1000*abs(t))))
% Plots
subplot(1,1,1)
subplot(2,1,2);plot(t*1000,xa);
xlabel('t in msec.'); ylabel('xa(t)')
title('Reconstructed Signal from x1(n) using sinc function'); hold on
stem(n*Ts*1000,x); hold off