DS.rar_Spectrum

% By Muhammad Faizan % 01-ET-31 % 17th Dec 2007 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Direct Sequence Spread Spectrum %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% clc clear % Generating the bit pattern with each bit 6 samples long b=round(rand(1,20)); pattern=[]; for k=1:20 if b(1,k)==0 sig=zeros(1,6); else sig=ones(1,6); end pattern=[pattern sig]; end plot(pattern); axis([-1 130 -.5 1.5]); title('\bf\it Original Bit Sequence'); % Generating the pseudo random bit pattern for spreading spread_sig=round(rand(1,120)); figure,plot(spread_sig); axis([-1 130 -.5 1.5]); title('\bf\it Pseudorandom Bit Sequence'); % XORing the pattern with the spread signal hopped_sig=xor(pattern,spread_sig); % Modulating the hopped signal dsss_sig=[]; t=[0:100]; fc=.1 c1=cos(2*pi*fc*t); c2=cos(2*pi*fc*t+pi); for k=1:120 if hopped_sig(1,k)==0 dsss_sig=[dsss_sig c1]; else dsss_sig=[dsss_sig c2]; end end figure,plot([1:12120],dsss_sig); axis([-1 12220 -1.5 1.5]); title('\bf\it DSSS Signal'); % Plotting the FFT of DSSS signal figure,plot([1:12120],abs(fft(dsss_sig)))