Direct Sequence Spread Spectrum (DS-BPSK)

This function is used to give a demo about generation of waveforms in direct sequence spread spectrum technique

function[st,mt]= DS_Spread_Spectrum(bt,ct_polar) 
//Caption:Direct Sequence Spread Coherent BPSK
//Generation of waveforms in DS/BPSK spread spectrum transmitter
//bt: Input Data Sequence (bipolar format)
//ct_polar: Spreading code (bipolar format)
Ft = 0:0.01:1; 
//bt = [1*ones(1,N) -1*ones(1,N)];
t = 0:length(bt)-1;
//ct_polar = [-1,-1,1,1,1,-1,1,-1,-1,1,1,1,-1,1];
mt = bt.*ct_polar;
Carrier = 2*sin(Ft*2*%pi);
st = [];
for i = 1:length(mt)
  st = [st mt(i)*Carrier];
end
//
figure
subplot(3,1,1)
a =gca();
a.x_location = "origin";
a.y_location = "origin";
a.data_bounds = [0,-2;20,2];
plot2d2(t,bt,5)
xlabel('                                                               t')
title('Data b(t)')
subplot(3,1,2)
a =gca();
a.x_location = "origin";
a.y_location = "origin";
a.data_bounds = [0,-2;20,2];
plot2d2(t,ct_polar,5)
xlabel('                                                                t')
title('Spreading code c(t)')
subplot(3,1,3)
a =gca();
a.x_location = "origin";
a.y_location = "origin";
a.data_bounds = [0,-2;20,2];
plot2d2(t,mt,5)
xlabel('                                                               t')
title('Product Signal m(t)')
//
figure
subplot(3,1,1)
a =gca();
a.x_location = "origin";
a.y_location = "origin";
a.data_bounds = [0,-2;20,2];
plot2d2(t,mt,5)
xlabel('                                                                t')
title('Product Signal m(t)')
subplot(3,1,2)
a =gca();
a.x_location = "origin";
a.y_location = "origin";
a.data_bounds = [0,-2;20,2];
plot(Carrier)
xlabel('                                                               t')
title('Carrier Signal')
subplot(3,1,3)
a =gca();
a.x_location = "origin";
a.y_location = "origin";
a.data_bounds = [0,-2;20,2];
plot(st)
xlabel('                                                               t')
title('DS/BPSK signal s(t)')
endfunction
//Result
//->bt = [1,1,1,1,1,1,1,-1,-1,-1,-1,-1,-1,-1]
// bt  =
// 
//    1.    1.    1.    1.    1.    1.    1.  - 1.  - 1.  - 1.  - 1.  - 1.  - 1.  - 1.  
// 
//-->ct_polar = [-1,-1,1,1,1,-1,1,-1,-1,1,1,1,-1,1]
// ct_polar  =
// 
//  - 1.  - 1.    1.    1.    1.  - 1.    1.  - 1.  - 1.    1.    1.    1.  - 1.    1.  
// 
//-->exec('C:\Users\SENTHILKUMAR\Desktop\Communication_Toolbox\Digital_Communication\DS_Spread_Spectrum.sci', -1)
// 
//-->[st,mt]= DS_Spread_Spectrum(bt,ct_polar)
// mt  =
// 
//  - 1.  - 1.    1.    1.    1.  - 1.    1.    1.    1.  - 1.  - 1.  - 1.    1.  - 1.