用MATLAB产生回声的源代码

clear all 
close all 
%channel system order 
sysorder = 5 ; 
% Number of system points 
N=2000; 
inp = randn(N,1); 
n = randn(N,1); 
[b,a] = butter(2,0.25); 
Gz = tf(b,a,-1); 
%This function is submitted to make inverse Z-transform (Matlab central file exchange) 
%The first sysorder weight value 
%h=ldiv(b,a,sysorder)'; 
% if you use ldiv this will give h :filter weights to be 
h= [0.0976; 
0.2873; 
0.3360; 
0.2210; 
0.0964;]; 
y = lsim(Gz,inp); 
%add some noise 
n = n * std(y)/(10*std(n)); 
d = y + n; 
totallength=size(d,1); 
%Take 60 points for training 
N=60 ; 
%begin of algorithm 
w = zeros ( sysorder , 1 ) ; 
for n = sysorder : N 
u = inp(n:-1:n-sysorder+1) ;