FHSS_DSSS_CDMA.rar_cdma 直扩_直扩_跳频 解调_跳频直扩解调_跳频解调

% Lab 06 % WiCom_1 % By Kashif Shahzad % 01-ET-31 % 3rd July 2004 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Frequency Hopping Spread Spectrum %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% clc clear % Generation of bit pattern s=round(rand(1,25)); % Generating 20 bits signal=[]; carrier=[]; t=[0:2*pi/119:2*pi]; % Creating 60 samples for one cosine for k=1:25 if s(1,k)==0 sig=-ones(1,120); % 120 minus ones for bit 0 else sig=ones(1,120); % 120 ones for bit 1 end c=cos(t); carrier=[carrier c]; signal=[signal sig]; end subplot(4,1,1); plot(signal); axis([-100 3100 -1.5 1.5]); title('\bf\it Original Bit Sequence'); % BPSK Modulation of the signal bpsk_sig=signal.*carrier; % Modulating the signal subplot(4,1,2); plot(bpsk_sig) axis([-100 3100 -1.5 1.5]); title('\bf\it BPSK Modulated Signal'); % Preparation of 6 new carrier frequencies t1=[0:2*pi/9:2*pi]; t2=[0:2*pi/19:2*pi]; t3=[0:2*pi/29:2*pi]; t4=[0:2*pi/39:2*pi]; t5=[0:2*pi/59:2*pi]; t6=[0:2*pi/119:2*pi]; c1=cos(t1); c1=[c1 c1 c1 c1 c1 c1 c1 c1 c1 c1 c1 c1]; c2=cos(t2); c2=[c2 c2 c2 c2 c2 c2]; c3=cos(t3); c3=[c3 c3 c3 c3]; c4=cos(t4); c4=[c4 c4 c4]; c5=cos(t5); c5=[c5 c5]; c6=cos(t6); % Random frequency hopps to form a spread signal spread_signal=[]; for n=1:25 c=randint(1,1,[1 6]); switch(c) case(1) spread_signal=[spread_signal c1]; case(2) spread_signal=[spread_signal c2]; case(3) spread_signal=[spread_signal c3]; case(4) spread_signal=[spread_signal c4]; case(5) spread_signal=[spread_signal c5]; case(6) spread_signal=[spread_signal c6]; end end subplot(4,1,3) plot([1:3000],spread_signal); axis([-100 3100 -1.5 1.5]); title('\bf\it Spread Signal with 6 frequencies'); % Spreading BPSK Signal into wider band with total of 12 frequencies freq_hopped_sig=bpsk_sig.*spread_signal; subplot(4,1,4) plot([1:3000],freq_hopped_sig); axis([-100 3100 -1.5 1.5]); title('\bf\it Frequency Hopped Spread Spectrum Signal'); % Expressing the FFTs figure,subplot(2,1,1) plot([1:3000],freq_hopped_sig); axis([-100 3100 -1.5 1.5]); title('\bf\it Frequency Hopped Spread Spectrum signal and its FFT'); subplot(2,1,2); plot([1:3000],abs(fft(freq_hopped_sig)));