bpsk.asv

主要用来进行MATLAB中AWGN的识别算法!

% bpsk.m
%
% Simulation program to build BPSK modulation singal


%************************ Preparation part *****************************
NUM = 1024;            % The number of FFT point
sr=1000000.0;          % Symbol rate
fc = 1000000;          % The frequency of the carrier
fs = 32000000;         % The sample rate
ml=1;                  % Number of modulation levels
br=sr.*ml;             % Bit rate (=symbol rate in this case)
nd=NUM*fc/fs;         % The number of symbols
n =fc/sr;              % The number of the carrier in a symbol
ebno=15;               % Eb/N0
IPOINT=32;             % Number of oversamples
Ts = 1/sr;             % The period of the sourse signal

t=0:1/fs:1/fc*nd*n-1/fs;    % The sample point in one carrier period
fcos = cos(2*pi*fc*t);      % cosin carrier

%*********************** Filter initialization **************************

irfn=21;                                 % Number of filter taps
alfs=0.33;                                % Rolloff factor
[xh]=hrollfcoef(irfn,IPOINT,sr,alfs,1);  % Transmitter filter coefficients
%fprintf('%f\n',xh);

%*********************** Data generation **********************************
data=rand(1,nd)>0.5;                     % rand: built in function
%>>>>>>>>>>>>>>fprintf('%d',data);

%*********************** Bpsk modulation **********************************

%data1=data.*2-1;
[data2]=oversample(data,nd,IPOINT);
data3=conv(data2,xh);                                %(conv: build in function)
%fprintf('%f\n',data3);
data4=data3(irfn*IPOINT/2-2:NUM+irfn*IPOINT/2-3);    % date4 is the baseband singal of BPSK 

modulation = data4.*fcos;                            % The modulation is the BPSK singal

%*********************** find the ampitude and phase **********************************

modulation=modulation+0.001;
hxn=hilbert(modulation);
y=imag(hxn);
x=real(hxn);
z=sqrt(x.*modulation+y.*y);                 %z is ampitute


zint=ceil(10000*z);                                 % save the result
fprintf('\n');                                      % 
fprintf('%d,\n',zint);                              %



z_ph1=y./x;
for i=1:NUM
    if (y(i)>0)&(x(i)>0)
        z_ph(i)=atan(z_ph1(i));
    elseif (y(i)>0)&(x(i)<0)
        z_ph(i)=pi+atan(z_ph1(i));
    elseif (y(i)<0)&(x(i)<0)
        z_ph(i)=pi+atan(z_ph1(i));
    elseif (y(i)<0)&(x(i)>0)
        z_ph(i)=2*pi+atan(z_ph1(i));
    elseif (y(i)>0)&(x(i)==0)
        z_ph(i)=0.5*pi;
    elseif (y(i)<0)&(x(i)==0)
        z_ph(i)=1.5*pi;
    end                                                 %  z_ph is the phase
end


%*************************find the rmax********************************
%x(1)=0;
%for i=1:length(z)-1                             % 
%    x(i+1)=x(i)+z(i);
%     ma=x(1024)/NUM;
%end

a=sum(z);
ma=a/NUM;

for i=1:length(z) 
  an(i)=z(i)./ma;
  an(i)=an(i)-1;
  an(i)=an(i)*an(i);
end
  %fprintf('%f\n',an);
  y1=fft(an,NUM);
  yxk=abs(y1(1:NUM/2));
  
 for i=1:NUM/2
    for j=1:NUM/2-i
        t=yxk(j);yxk(j)=yxk(j+1);yxk(j+1)=t;
    end
end
%fprintf('%f\n',yxk);
max=10*yxk(NUM/2)/NUM;
fprintf('\nrmax=%f',max);