MATLAB.rar_matlab codes

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% BASE BAND Direct %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Sequence Spread Spectrum using GOLD CODE %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% clc; close all; b=round(rand(1,40)); pattern=[]; for k=1:40 if b(1,k)==0 sig=zeros(1,6); else sig=ones(1,6); end pattern=[pattern sig]; end b1=b; message = b1 message1 = pattern; subplot(3,2,1) plot(pattern); axis([-1 200 -.5 1.5]); ylabel('\bf Original Bit Sequence'); title('\bf\it TRANSMITTED MESSAGE'); %-------------------------------------------------------------------------- % Generation of Gold code No. 1 G=20; % Code length K=1; % Number of Codes or code sequences %..............Generation of first PN sequence............... lsr1 =randsrc(1,20,[0 1]); PN1=[]; for j=1:G PN1=[PN1 lsr1(1)]; temp1 = xor(lsr1(4),lsr1(1)); temp2 = xor(lsr1(6),temp1); temp3 = xor(lsr1(7),temp2); temp4 = xor(lsr1(13),temp3); temp5 = xor(lsr1(19),temp4); for i=1:G-1 lsr1(i)=lsr1(i+1); %----Shifting---- end lsr1(20)=temp5; end %..............Generation of Second PN sequence.............. lsr2 =randsrc(1,20,[0 1]); PN2=[]; for j=1:G PN2=[PN2 lsr2(1)]; temp1 = xor(lsr2(2),lsr1(1)); temp2 = xor(lsr2(3),temp1); temp3 = xor(lsr2(5),temp2); temp4 = xor(lsr2(7),temp3); temp5 = xor(lsr2(9),temp4); temp6 = xor(lsr2(10),temp5); temp7 = xor(lsr2(13),temp6); temp8 = xor(lsr2(14),temp7); temp9 = xor(lsr2(16),temp8); temp10 = xor(lsr2(17),temp9); temp11 = xor(lsr2(19),temp10); for i=1:G-1 lsr2(i)=lsr2(i+1); %----Shifting---- end lsr2(20)=temp11; end %..............Generation of Gold Codes.................... Code_Matrix=[]; for codes=1:K code=[]; for j=1:G code=[code xor(PN1(j),PN2(j))]; end Code_Matrix=[Code_Matrix code']; end gold_1 = Code_Matrix'; Gold_Code = gold_1; pattern=[]; for k=1:20 if gold_1(1,k)==0 sig=zeros(1,6); else sig=ones(1,6); end pattern=[pattern sig]; end gold=pattern; subplot(3,2,3); plot(pattern); axis([-1 120 -.5 1.5]); ylabel('\bf Gold Code'); %--------------------------------------- % b1 = Message Matrix (1,20) % gold_1 = Gold Matrix (1,20) %--------------------------------------- % Spreading the pattern with the gold code k=1; for i=1:20 for j=1:20 spread(1,k)=xor(b1(1,i),gold_1(1,j)); k=k+1; end end spread; subplot(3,2,5); plot(spread); axis([-1 400 -.5 1.5]); ylabel('\bf Spreaded Sequence'); %-------------------------------------------------------------------------- %-------------------------------------------------------------------------- %--------------------------------RECEIVER---------------------------- %-------------------------------------------------------------------------- subplot(3,2,2); plot(spread); axis([-1 400 -.5 1.5]); ylabel('\bf Received Sequence'); title('\bf\it RECEIVED MESSAGE'); %------GOLD CODE sequence used----- gold_2=gold_1; pattern=[]; for k=1:20 if gold_2(1,k)==0 sig=zeros(1,6); else sig=ones(1,6); end pattern=[pattern sig]; end gold = pattern; subplot(3,2,4); plot(gold); axis([-1 120 -.5 1.5]); ylabel('\bf Gold Code'); %-------Demodulation to get original message signal--------- gold_2inv = xor(1,gold_2); i=1; k=1; while k < 400 s=0; for j=1:20 temp(1,j) = xor(spread(1,k),gold_2(1,j)); k=k+1; s=s+temp(1,j); end if(s==0) b2(1,i) = 0; else b2(1,i) = 1; end i=i+1; end despreaded_signal = b2 %-----Plotting Despreaded signal------ pattern=[]; for k=1:20 if b2(1,k)==0 sig=zeros(1,6); else sig=ones(1,6); end pattern=[pattern sig]; end subplot(3,2,6); plot(pattern); axis([-1 120 -.5 1.5]); ylabel('\bf Despreaded Sequence'); % Plotting the FFT of DSSS signal % figure,plot([1:400],abs(fft(spread)),[1:20],abs(fft(b2)))