ip_06_07.m

这是通信系统仿真的第六章的例题的仿真程序代码！挺好的

% MATLAB script for Illustrative Problem 6.7.
close all
clear all

echo on
N=31;
T=1;
alpha=1/4;
n=-(N-1)/2:(N-1)/2;			% the indices for g_T
% The expression for g_T is obtained next.
for i=1:length(n),
  g_T(i)=0;
  for m=-(N-1)/2:(N-1)/2,
    g_T(i)=g_T(i)+sqrt(xrc(4*m/(N*T),alpha,T))*exp(j*2*pi*m*n(i)/N);
    echo off ;
  end;
end;
echo on ;
g_T=real(g_T) ; % The imaginary part is due to the finite machine precision
% Derive g_T(n-(N-1)/2).
n2=0:N-1;
figure(1)
stem(n2,g_T)
hgsave('fig_ip0607_1')

[G_T,W]=freqz(g_T,1); % Get the frequency response characteristics.
magG_T_in_dB=20*log10(abs(G_T)/max(abs(G_T)));  	% normalized magnitude response
figure(2);
plot(W/(2*pi),magG_T_in_dB);
% impulse response of the cascade of the transmitter and the receiver filters
g_R=g_T;
imp_resp_of_cascade=conv(g_R,g_T);
hgsave('fig_ip0607_2')
figure(3);
%plot(zeros(size([0:2*N-1])));
hold;

stem([1:2*N-1],imp_resp_of_cascade);
hgsave('fig_ip0607_3')

% Plotting commands follow.