2_6.rar_DELAY IN DSSS_FOE_acqusition_acqusition of DSSS_dsss

function main_1=final_qpsk() %%%DSSS parameters clc close all M=4;%Size of signal constellation k = log2(M); % Number of bits per symbol num = 10e0; % Number of bits to process nsamp = 8; % Oversampling rate brate = 9.6e3; % bit rate degri=6; code_size=(2^degri)-1; rchip = brate*code_size; % Chip rate,Tc=1/rchip sym_rate=(rchip/2); fchip=1/rchip; fs=(sym_rate*nsamp); fc=fs/4; Tsym=1/sym_rate; Tsamp=Tsym/nsamp; SNR=10;%[-15:5]; thershold=[.1:.1:1]; iterate=1; final_prob=zeros(1,iterate); thershold=30; %% data generation % Create a binary data stream as a column vector. for q_snr=SNR for z=1:iterate close all inp_data=randint(1,2*num); temp=reshape(inp_data,2,num); rdata_I=temp(1,:); rdata_Q=temp(2,:); [m n]=size(rdata_I); %% bit-to-Symbol Mapping % Convert the chips in spread_I(Q) into k-bit symbols mat_bin=[2 1]; modulate1=mat_bin*[rdata_I;rdata_Q]; %% gray coding % C. Map from binary coding to Gray coding. mapping = [0 1 3 2]; modulate_gray = mapping(modulate1+1); %% diffrential encoding diff_modulate1=[]; diff_modulate1(1)=modulate_gray(1); for k=2:length(modulate_gray) diff_modulate1(k)=mod(modulate_gray(k)+diff_modulate1(k-1),4); end %% base band modulation [m3 n3]=size(diff_modulate1); gray_diff_modulate=zeros(size(diff_modulate1)); gray_diff_modulate(diff_modulate1==0)=sqrt(2)/2*(1+j); gray_diff_modulate(diff_modulate1==1)=sqrt(2)/2*(-1+j); gray_diff_modulate(diff_modulate1==2)=sqrt(2)/2*(-1-j); gray_diff_modulate(diff_modulate1==3)=sqrt(2)/2*(1-j); % gray_diff_modulate = modulate(modem.qammod(M),diff_modulate1); gray_diff_modulated_I=real(gray_diff_modulate); gray_diff_modulated_Q=imag(gray_diff_modulate); %% scater Plot of Symbols % Plot first 10 symbols in a stem plot. if z==iterate temp2=[gray_diff_modulate]; scatterplot(temp2',nsamp,0,'rx');%rcv_a,N,0,'bx' end %% Filter Definition % Define filter-related parameters. filtorder = 40; % Filter order delay = filtorder/(nsamp); % Group delay (# of input samples) cutoff= (sym_rate)/2;%(symbol rate)/2 rolloff = 0.25; % Rolloff factor of filter rrcfilter = rcosine(1,nsamp,'fir/sqrt',rolloff,delay); % [b1 a1] = firrcos(filtorder,cutoff,rolloff,fs,'rolloff'); if z==iterate figure(2); impz(rrcfilter,1); figure(3); freqz(rrcfilter,1); end %% data spereder [spreader_cod_I spreader_cod_Q]=g_bitstream(code_size);%code_generator function generate m-sequence code temp=xcorr(spreader_cod_Q); if z==iterate figure(6) stem(temp) end [m4 n4]=size(gray_diff_modulated_I); if z==iterate figure(7) y=xcorr(spreader_cod_Q); stem(y) end for l=1:n4 spread_I1(l,:)=(spreader_cod_I.*gray_diff_modulated_I(l)); spread_Q1(l,:)=(spreader_cod_Q.*gray_diff_modulated_Q(l)); end [m1 n1]=size(spread_I1); spread_I=reshape(spread_I1',1,(m1*n1)); spread_Q=reshape(spread_Q1',1,(m1*n1)); %% Transmitted Signal after spreading % Upsample and apply square root raised cosine filter. % trans_up_I=rectpulse(spread_I,nsamp); % trans_up_Q=rectpulse(spread_Q,nsamp); % trans_sig_I = filter(b1,a1,trans_up_I); % trans_sig_Q = filter(b1,a1,trans_up_Q); trans_sig_I = rcosflt(spread_I,1,nsamp,'filter',rrcfilter); trans_sig_Q = rcosflt(spread_Q,1,nsamp,'filter',rrcfilter); trans_sig=trans_sig_I+j*trans_sig_Q; %% Create eye diagram for part of filtered signal. % ploteye(trans_I(filtorder/2:2000), nsamp); %% plot spectrum after spreading %I branch spectrum if z==iterate figure(8) L1=length(trans_sig_I);%length(symbol); NFFT = 2^nextpow2(L1); % Next power of 2 from length of y Y1 = fft(trans_sig_I,NFFT)/L1; f = fs/2*linspace(0,1,NFFT/2); %%%%%% Plot single-sided amplitude spectrum. plot(f,2*abs(Y1(1:NFFT/2))) title('Single-Sided Amplitude Spectrum after spreding') xlabel('Frequency (Hz)') ylabel('|Y(f)|') end %% modulation if fc >= fs/2, error(generatemsgid('InvalidRange'),'The carrier frequency must be less than half the sampling frequency.'); end [r,c]=size(trans_sig); if r*c == 0, trans_IF_R = []; end if (r==1), % convert row vector to column trans_IF_R = trans_IF_R(:); len = c; else len = r; end t = (0:1/fs:((len-1)/fs))'; t = t(:,ones(1,size(trans_sig,2))); trans_IF_R = real(trans_sig).*cos(2*pi*fc*t)+imag(trans_sig).*sin(2*pi*fc*t); % trans_IF_R=real(trans_IF); figure() L1=length(trans_IF_R);%length(symbol); NFFT = 2^nextpow2(L1); % Next power of 2 from length of y Y1 = fft(trans_IF_R,NFFT)/L1; f = fs/2*linspace(0,1,NFFT/2); %%%%%% Plot single-sided amplitude spectrum. plot(f,2*abs(Y1(1:NFFT/2))) title('Single-Sided Amplitude Spectrum after spreding') xlabel('Frequency (Hz)') ylabel('|Y(f)|') %% Channel % fd = 2e5; % Maximum Doppler shift (Hz) % h=rayleighchan(Tsamp,fd); % h.StoreHistory = true; % Allow states to be stored % fad_sig=filter(h,trans_IF_R); % % Send signal over an AWGN channel. EbNo = 50; % In dB snr = EbNo + 10*log10(k) - 10*log10(code_size); ynoisy = awgn(trans_IF_R,snr); %% random delay generation % w=(floor(rand(1,30+floor(10*rand(1)+1))+0.5)-.5)*2; % rxsig=[w,y_pasband]; %% demod recived _IF yf=ynoisy; [r,c]=size(yf); if r*c == 0, yrx_IQ = []; end if (r==1), % convert row vector to column yf = yf(:); len = c; else len = r; end t = (0:1/fs:((len-1)/fs))'; t = t(:,ones(1,size(yf,2))); x_I = yf.*cos(2*pi*fc*t); [b,a]=butter(5,fc*2/fs); for i = 1:size(yf,2), x_I(:,i) = filtfilt(b,a,x_I(:,i)); end t = (0:1/fs:((len-1)/fs))'; t = t(:,ones(1,size(yf,2))); x_Q = yf.*sin(2*pi*fc*t); [b,a]=butter(5,fc*2/fs); for i = 1:size(yf,2), x_Q(:,i) = filtfilt(b,a,x_Q(:,i)); end yrx_IQ=x_I+j*x_Q; %% reciver yrx_I_f = rcosflt(real(yrx_IQ),1,nsamp,'Fs/filter',rrcfilter); % yrx_I = downsample(yrx_I,nsamp); % Downsample. yrx_I = yrx_I_f(2*delay+1:end-2*delay); % Account for delay. yrx_Q_f = rcosflt(imag(yrx_IQ),1,nsamp,'Fs/filter',rrcfilter); % yrx_Q = downsample(yrx_Q,nsamp); % Downsample. yrx_Q = yrx_Q_f(2*delay+1:end-2*delay); % Account for delay. xI_rcos_down = downsample(yrx_I_f,nsamp); % Downsample. xI_rcos_down = xI_rcos_down(2*delay+1:end-2*delay); % Account for delay. xQ_rcos_down = downsample(yrx_Q_f,nsamp); % Downsample. xQ_rcos_down = xQ_rcos_down(2*delay+1:end-2*delay); % Account for delay. % xI_rcos_down=[x_rcos_I]; % xQ_rcos_down=[x_rcos_Q]; yrx=yrx_I+j*yrx_Q; %% Scatter Plot % Create scatter plot of received signal before and % after filtering. h = scatterplot(sqrt(nsamp)*yrx_IQ(1:nsamp*5e2),nsamp,0,'g.'); hold on; scatterplot(yrx(1:5e2),1,0,'kx',h); title('Received Signal, Before and After Filtering'); legend('Before Filtering','After Filtering'); axis([-5 5 -5 5]); % Set axis ranges. %% acquisition % %%%%acquisition %%%%%%%%% spreader_cod_I_up=upsample(spreader_cod_I,nsamp); spreader_cod_Q_up=upsample(spreader_cod_Q,nsamp); M=1000;% M denot the number of chips we should check in recived signal DMF_length=(code_size*nsamp); % the number of tap in DMF %%%%adaptive parameter sum_length=3; %%inth article with "L" notation window_length=8; const_cof_ther=.426;%%(false alarm prob=.01) sort_const_cof_ther=1.3;%%(false alarm prob=.01) K=6; number_seg_I=fix((length(yrx_I))/DMF_length); number_seg_code=fix((length(spreader_cod_I_up))/DMF_length); cof_DMF_I=spreader_cod_I_up(1,(1:DMF_length)); cof_DMF_Q=spreader_cod_Q_up(1,(1:DMF_length)); yrx_I=yrx_I'; yrx_