pr6_47m.m

Spread Spectrum and CDMA Principles and Applications 书籍和代码

%Problem 6.47 modified;
%finds first binary primitive polynomial;

clear all; close all;
fprintf('\n');
n=14; %set degree of polynomial;
N=2^n-1; %m-sequence length;
din=[1,zeros(1,n-1)]; %initial LFSR loading;
Rm=0; k=1; %initialization of search;
while Rm>-0.9
    f=[1 bitget(k,1:n-1) 1]; d=lseq(f,din); a=-2*d+1; %calculates linear sequence and concverts it to binary {+1,-1} alphabet;
    R=xcorr(a); %calculates ACF
    Rm=max(R(N+1:2*N-1)+R(1:N-1)); %test whether we came to m-sequence or other sequence by checking periodic ACF;
    k=k+1;
end;
disp('primitive polynomial');
disp(f);
beep;