This is the code for FFT Accumulation Method using autocorrelation.correct this code .we are receiving an error as Function definitions are not permitted in this context.
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PLACEIUS NISHIGA G
on 11 Jan 2018
Answered: John D'Errico
on 11 Jan 2018
clc;
clear all;
close all;
Tu=224e-6;
T=Tu/2048;
G=0;
delta=G*Tu;
Ts=delta+Tu;
Kmax=2000;
Kmin=0;
FS=4096;
q=10;
fc=q*1/T;
Rs=4*fc;
t=0:1/Rs:Tu;
M=Kmax+1;
rand('state',0);
a=-1+2*round(rand(M,1)).'+i*(-1+2*round(rand(M,1))).';
A=length(a);
info=zeros(FS,1);
figure(1);
stem(a );
info(1:(A/2)) = [ a(1:(A/2)).'];
info((FS-((A/2)-1)):FS) = [ a(((A/2)+1):A).'];
carriers=FS.*ifft(info,FS);
tt=0:T/2:Tu;
figure(2);
subplot(211);
stem(tt(1:100),real(carriers(1:100)));
title('subcar generation');
subplot(212);
stem(tt(1:500),imag(carriers(1:500)));
figure(3);
f=(1:(FS))/(FS);
subplot(211);
plot(f,abs(fft(carriers,FS)/FS));
x=real(carriers);
fs=4096/Tu;
df=1/Tu;
dalpha=2098/Tu;
function [Sx, alphao, fo] =autofam(x, fs, df , dalpha)
Np=pow2 (nextpow2 (fs/df ) ) ;
L=Np/4;
P=pow2 (nextpow2 (fs/dalpha/L))
N=P*L;
if length (x) <N
x(N)=0;
elseif length (x) >N
x=x(l:N);
end
NN= (P-l) *L+Np;
XX=X;
Xx(NN)=0;
xx=xx ( : );
X=zeros (Np, P);
for k=0:P-l
X( : ,k+l) =xx(k*L+l:k*L+Np);
end
a=hamming (Np);
XW=diag(a) *X;
XW=X ;
XFl=fft (XW);
XFl=fftshift (XF1);
XF1= [XF1(:,P/2+l:P) XF1(:,l:P/2) ];
E= zeros (Np, P);
for k=-Np/2:Np/2-l
for m=0:P-l
E(k+Np/2+l,m+l) =exp(-i*2*pi*k*m*L/Np);
end
end
XD=XF1.*E;
XD=conj (XD' );
XM=zeros (P,Np^2) ;
for k=l:Np
for l=1:Np
XM(:,(k-l)*Np+l)=(XD(:,k) .*conj(XD(:,1) ) );
end
end
XF2=fft (XM);
XF2=fftshift (XF2);
XF2= [XF2(:,Np^2/2+l:Np^2 ) XF2(:,l:Np^2/2) ];
XF2=XF2 (P/4 : 3*P/4 , : );
M=abs (XF2);
alphao=-l:l/N:l;
fo=-.5:l/Np: .5;
Sx=zeros (Np+1, 2*N+1)
for kl=l: P/2+1
for k2=l:Np^2
if rem(k2,Np) ==0
l=Np/2-l;
else
l=rem(k2,Np) -Np/2-1;
end
k=ceil (k2/Np) -Np/2-1;
p=kl-P/4-l;
alpha= (k-1) /Np+ (p-1) /L/P;
f=(k+l)/2/Np;
if alpha<-l | alpha>l
k2=k2+l;
elseif f<-.5 | f> .5
k2=k2+l;
else
kk=1+Np*(f+.5);
ll=1+N*(alpha+1);
Sx(kk,ll) =M(kl,k2);
end
end
end
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Accepted Answer
John D'Errico
on 11 Jan 2018
Older releases of MATLAB do not allow functions to be defined as part of script. So either learn to save your functions as an m-file, or get a current release of MATLAB.
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