close all;
clear all;
%--------------------
% Generates baseband signal for the COM-8001 pattern generator
% Format is 2 (complex) * 10-bit (unsigned).
%--------------------
fs = 64;
nsamples = 64;	    % simulation duration, expressed as number of complex samples
n_b = 20;			 % Number of Data Bits
gain = .3;			 % prevent saturation at the D/A converter

% for long simulations, store results in output file
[fid_o1,message]  = fopen('pn32spread429a.bin','w');
if(fid_o1 == -1)
   message
end

% initialization
last_i = 0;
last_q = 0;
current_i = 0;
current_q = 0;
b = dec2bin(0,10);

%data that will be transmitted x(t)
%Collected data from sensors length of 19

xt_ip = 2*(rand(1,(n_b-1))>.5) - 1;
%xt_ip = rand(1,n_b)>.5;

%add 1 to begining of xt to make sequence length of 20
%this is for when receiving, you always know there is a 1
%in the beginning
xt_ipnew = [1 ; xt_ip.'];
xt_ipnew = xt_ipnew.';

xt = kron(xt_ipnew, ones(1,nsamples));
newxt = gain*xt;



%------------------------------------------------------
% MAIN LOOP
%------------------------------------------------------
% loop signal processing
  
%adding sequence for time sync
ts = .5*[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];

%PN code
pn = [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];

k=1;
for i = 1:length(pn)
   pnf(k:k+1) = pn(i);
   k=k+2;
end

pnnew = kron(ones(1,n_b), pnf);
pn_new = gain*pnnew;

%mix pn code with data sequence
new_xt = xt.*pn_new;

%design cosine filter
yf = rcosine(1,8,'fir');



%upsample and filter
yo = rcosflt(new_xt, 1, 8, 'filter', yf);
tsf = rcosflt(ts, 1, 8, 'filter',yf);
   
%data needed for trasmitting
newyo = yo(25:5168-24);
%newyo= yo;
%make sure to copy this matrix to receiver code 
newts = tsf(25:304-24);
%newts = tsf;

%this is final signal with time sync sequence attached to front 
signali = [tsf  ; yo];
signalq = [tsf  ; yo];
   
for j = 1:length(signali)
	i = j;  
   % convert samples to 10-bit unsigned format
   sigt2i = min(max((floor((signali(i)+1.)*511.5)),0.),1023);
   sigt2q = min(max((floor((signalq(i)+1.)*511.5)),0.),1023);
   
   %invert bit order because of pinout
   a = dec2bin(sigt2i, 10);
   b(1) = a(10);
   b(2) = a(9);
   b(3) = a(8);
   b(4) = a(7);
   b(5) = a(6);
   b(6) = a(5);
   b(7) = a(4);
   b(8) = a(3);
   b(9) = a(2);
   b(10) = a(1);
   outputi = bin2dec(b);
   
   a = dec2bin(sigt2q, 10);
   b(1) = a(10);
   b(2) = a(9);
   b(3) = a(8);
   b(4) = a(7);
   b(5) = a(6);
   b(6) = a(5);
   b(7) = a(4);
   b(8) = a(3);
   b(9) = a(2);
   b(10) = a(1);
   outputq = bin2dec(b);
   
   % pack samples
   % wait until two complex samples are collected before writing into file
   if(mod(j,2) == 0)
      % even sample
      current_i = outputi;
      current_q = outputq;
      
      a = bitand(bitshift(last_q,-2), 255);
      fprintf(fid_o1,'%c',a);
      a = bitand(bitor(bitshift(last_q,6),bitshift(last_i,-4)),255);
      fprintf(fid_o1,'%c',a);
      a = bitand(bitor(bitshift(last_i,4),bitshift(current_q,-6)),255);
      fprintf(fid_o1,'%c',a);
      a = bitand(bitor(bitshift(current_q,2),bitshift(current_i,-8)),255);
      fprintf(fid_o1,'%c',a);
      a = bitand(current_i,255);
      fprintf(fid_o1,'%c',a);
      
      % keep track of simulation progress
      if(mod(j,10000) == 0)
         j/10000
     	end;
      
   else
      % odd sample
	   % remember last sample
      last_i = outputi;
      last_q = outputq;
   end;
end   

    figure(1)    
    %subplot(4,1,1)
    plot(xt)
    grid on;
    xlabel('Time');
    ylabel('Amplitude');
    legend('Data Stream - x(t)');
    
    figure(2)
    %subplot(4,1,2)
    plot(new_xt);
    grid on;
    xlabel('Time');
    ylabel('Amplitude');
    legend('Data Stream Mixed With PN Code');
    
    figure(3)
    %subplot(4,1,3)
    plot(signali, 'b');
    grid on;
    xlabel('Time');
    ylabel('Amplitude');
    legend('Filtered I Values');
    
    figure(4)
    %subplot(4,1,4)
    plot(signalq, 'r');
    grid on;
    xlabel('Time');
    ylabel('Amplitude');    
    legend('Filtered Q Values');
   
    % close opened files
fclose(fid_o1);