Communication Technology

I/Q Constellation

mlevel = 2;

n = 100;

s_i = round((mlevel-1)*rand(1,n))-(mlevel-1)/2;

s_q = round((mlevel-1)*rand(1,n))-(mlevel-1)/2;

plot(s_i,s_q,'-',s_i,s_q,'go'); axis([-mlevel/2 mlevel/2 -mlevel/2 mlevel/2]);

mlevel = 2;

n = 100;

rAmp = 0.1;

s_i = (round((mlevel-1)*rand(1,n))-(mlevel-1)/2) + (rAmp*rand(1,n)-0.5*rAmp);

s_q = round((mlevel-1)*rand(1,n))-(mlevel-1)/2 + (rAmp*rand(1,n)-0.5*rAmp);

plot(s_i,s_q,'-',s_i,s_q,'go'); axis([-mlevel/2 mlevel/2 -mlevel/2 mlevel/2]);

 

mlevel = 2;

n = 100;

rAmp = 0.1;

s_i = (round((mlevel-1)*rand(1,n))-(mlevel-1)/2) + (rAmp*rand(1,n)-0.5*rAmp);

s_q = round((mlevel-1)*rand(1,n))-(mlevel-1)/2 + (rAmp*rand(1,n)-0.5*rAmp);

 

% Folowing is to display digital pulse for the signal

sf = 10;

path_i = s_i;

path_q = s_q;

 

if sf > 1

   for i = 2:sf

    path_i= [path_i ; s_i];

    path_q= [path_q ; s_q]; 

   end

 

   path_i = reshape(path_i,[],1);

   path_q = reshape(path_q,[],1);

end

 

subplot(2,2,1); plot(path_i);axis([0 length(path_i) -mlevel/2 mlevel/2]);

subplot(2,2,3); plot(path_q);axis([0 length(path_i) -mlevel/2 mlevel/2]);

subplot(2,2,[2 4]); plot(path_i,path_q,'-',s_i,s_q,'go'); axis([-mlevel/2 mlevel/2 -mlevel/2 mlevel/2]);

 

mlevel = 2;

n = 100;

rAmp = 0.1;

s_i = (round((mlevel-1)*rand(1,n))-(mlevel-1)/2) + (rAmp*rand(1,n)-0.5*rAmp);

s_q = round((mlevel-1)*rand(1,n))-(mlevel-1)/2 + (rAmp*rand(1,n)-0.5*rAmp);

 

% Folowing is to display digital pulse for the signal

sf = 32;

path_i = s_i;

path_q = s_q;

 

if sf > 1

   for i = 2:sf

    path_i= [path_i ; s_i];

    path_q= [path_q ; s_q]; 

   end

 

   path_i = reshape(path_i,[],1);

   path_q = reshape(path_q,[],1);

end

 

 

b = fir1(128,0.10,'low');

 

path_i = filter(b,1,path_i);

path_q = filter(b,1,path_q);

 

subplot(2,2,1); plot(path_i);axis([0 length(path_i) -mlevel/2 mlevel/2]);

subplot(2,2,3); plot(path_q);axis([0 length(path_i) -mlevel/2 mlevel/2]);

subplot(2,2,[2 4]); plot(path_i,path_q,'-',s_i,s_q,'go'); axis([-mlevel/2 mlevel/2 -mlevel/2 mlevel/2]);