I need help.

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chen changlong
chen changlong 2011-5-8
hello eveyone!
I am a chinese,I am so gland to find this forum,it is a pleasure that eveyone in this forum is so kind.I have a problem that when I run the code below in matlab ,it show me 'Unexpected MATLAB expression'.I do not know why,can you help me?
%DVB-T 2K Reception
clear all;
close all;
Tu=224e-6;
T=Tu/2048;
G=0;
delta=G*Tu;
Ts=delta+Tu;
Kmax=1705;
Kmin=0;
FS=4096;
q=10;
fc=q*1/T;
Rs=4*fc;
t=0:1/Rs:Tu;
tt=0:T/2:Tu;
%Data generator
sM=2;
[x,y]=meshgrid((-sM+1):2:(sM-1),(-sM+1):2:(sM-1));
alphabet=x(:)+li*y(:);
N=Kmax+1;
rand('state',0);
a=-1+2*round(rand(N,1)).'+i*(-1+2round(rand(N,1))).';
A=length(a);
info=zeros(FS,1);
info(1:(A/2))=[a(1:(A/2)).'];
info((FS-((A/2)-1)):FS)=[a(((A/2)+1):A).'];
carriers=FS.*ifft(info,FS);
%Upconverter
L=length(carriers);
chips=[carriers.';zeros((2*q)-1,L)];
p=1/Rs:1/Rs:T/2;
g=ones(length(p),1);
dummy=conv(g,chips(:));
u=[dummy;zeros(46,1)];
[b,aa]=butter(13,1/20);
uoft=filter(b,aa,u);
delay=64;
s_tilde=(uoft(delay+(1:length(t))).').*exp(li*2*pi*fc*t);
s=real(s_tilde);
%OFDM RECEPTION
%Downconversion
r_tilde=exp(-li*2*pi*fc*t).*s;
fifure(1);
subplot(211);
plot(t,real(r_tilde));
axis([0e-7 12e-7 -100 150]);
grid on;
figure(2);
subplot(212);
pwelch(r_tilde,[],[],[],Rs);
%Carrier suppression
[B,AA]=butter(3,1/2);
r_info=2*filter(B,AA,r_tilde);
figure(3);
subplot(212);
plot(t,imag(r_info));
axis([0 12e-7 -60 60]);
grid on;
figure(3);
subplot(212);
plot(t,imag(r_info));
axis([0 12e-7 -100 150]);
grid on;
figure(4);
f=(2/T)*(1:(FS))/(FS);
subplot(211);
plot(ff,abs(fft(r_info,q*FS))/FS);
grid on;
subplot(212);
pwelch(r_info,[],[],[],Rs);
%Sampling
r_data=real(r_info(1:(2*q):length(t)))+li*imag(r_info(1:(2*q):length(t)));
figure(5);
subplot(211);
stem(tt(1:20),(real(r_data(1:20))));
axis[0 12e-7 -60 60]);
grid on;
figure(5);
subplot(212);
strm(tt(1:20),(imag(r_data(1:20))));
axis([0 12e-7 -100 150]);
grid on;
figure(6);
f=(2/T)*(1:(FS))/(FS);
subplot(211);
plot(f,abs(fft(r_data,FS))/FS);
grid on;
subplot(212);
pwelch(r_data,[],[],[],2/T);
%FFT
info_2N=(1/FS).*fft(r_data,FS);
info_h=[info_2N(1:A/2) info_2N((FS-((A/2)-1)):FS)];
%slicing
for k=1:N,
a_hat(k)=alphabet((info_h(k)-alphabet)==min(info_h(k)-alphabet));
end;
figure(7)
plot(info_h((1:A)),'.k');
title('info-h Received Constellation')
axis square;
axis equal;
figure(8)
plot(a_hat((1:A)),'or');
title('a_hat 4-QAM')
axis square;
axis equal;
grid on;
axis([-1.5 1.5 -1.5 1.5]);
Thank you very much!
  1 个评论
chen changlong
chen changlong 2011-5-8
I am so sorry that the format is so terrible.

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采纳的回答

Andrew Newell
Andrew Newell 2011-5-8
Thank you for formatting it. Do you use the MATLAB editor? It displays syntax errors on the right margin as red lines. You can click on the line to see what the error is and take you to its location. For example, this line
a=-1+2*round(rand(N,1)).'+i*(-1+2round(rand(N,1))).';
gets an "invalid syntax" error because there is a missing multiplication sign:
a=-1+2*round(rand(N,1)).'+i*(-1+2*round(rand(N,1))).';
This line:
axis[0 12e-7 -60 60]);
gets a "Parse error at )" message. You forgot the left parenthesis:
axis([0 12e-7 -60 60]);
The orange lines provide useful advice too.
  1 个评论
chen changlong
chen changlong 2011-5-9
thank you very much ?
it can run now.
and i have learnd something about matlab from your answer.

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