pr6_43.m

Spread Spectrum and CDMA Principles and Applications 书籍和代码

%Problem 6.43
%Calculating ACFs of an arbitrary sequence;

close all;
Seq={[1,-1];[1,1,-1];[1,1,-1,1];[1,1,1,-1,1];[1,1,1,-1,-1,1,-1];[1,-1,1,1,-1,1,1,1,-1,-1,-1];[1,1,1,1,1,-1,-1,1,1,-1,1,-1,1];[1,1,1,1,1,-1,1,0,1,0,-1,1,1,-1,0,0,1,-1,0,-1,-1]}; %cell matrix of explored sequences,anything can be added;
a=Seq{7}; %setting explored sequence, may be taken arbitrary, too;
N=length(a); %length of sequence;
acc=sum(a)^2; %constant component of sequence;
Ra=xcorr(a); %aperiodic ACF;
Ra=[0,Ra,0]; Rp=Ra(N+1:end)+Ra(1:N+1); %periodic ACF;
acsum=sum(Rp(1:N)); %sum of PACF values;
shift=unidrnd(N,1,2); %two arbitrary shifts;
dlt=Rp(shift(1))-Rp(shift(2)); %difference of two ACF values;
NM=a*a'; mm=min(min(Ra),min(Rp))/NM; %squared norm of a and lower limits of normalized ACFs;
plot([0:N+2],[Ra(N+1:end),0,0]/NM,'r',[0:N+2],[Rp,Rp(2:3)]/NM,'b'); xlim([0,N+2]); ylim([mm-0.2,1.2]); ylabel('\rho(\tau)'); xlabel('\tau/\Delta'); grid;
fprintf('\n');
disp('     sumRp    SqCC     Rp(m)-Rp(l)'); 
disp([acsum,acc,dlt]);