fsk.zip_FSK ???_FSK demodulator

%sim_FSK_bandpass_coherent.m % simulates a digital communication system % with coherent FSK signaling in Fig.7.4.1 %Copyleft: Won Y. Yang, wyyang53@hanmail.net, CAU for academic use only clear, clf b=1; M=2^b; % # of bits per symbol and the modulation order SNRbdBt=0:0.1:10; SNRbt=10.^(SNRbdBt/10); ss=[0; 1]; % Set of symbols pobet= Q(sqrt(SNRbt/2)); % Eq.(7.2.9) Tb=1; Ts=b*Tb; % Bit/Symbol time Ns=40; T=Ts/Ns; LB=4*Ns; LBN1=LB-Ns+1; % Sample time and Buffer size Es=2; % Energy of signal waveform % BFSK signal waveforms wc=8*pi; dw=2*pi; w=wc+[0:M-1]*dw; wcT=wc*T; t=[0:Ns-1]*T; tt= [0:LB-1]*T; nd=0; % Number of delay samples td=0; % td=nd*T; % Delay time (time difference between XMTR and RCVR) for m=1:M su(m,:)=sqrt(2/Ts)*cos(w(m)*(t-td)); sw(m,:)=sqrt(2*Es/Ts)*cos(w(m)*t); end suT= su*T; SNRdBs=[1:10]; MaxIter=10000; % Range of SNRbdB and # of iterations for iter=1:length(SNRdBs) SNRbdB= SNRdBs(iter); SNR=10^(SNRbdB/10); N0=2*(Es/b)/SNR; sigma2=N0/2; sgmsT=sqrt(sigma2/T); st=zeros(1,LB); y=zeros(M,LB); r=zeros(1,LB); yr=zeros(M,LB); nobe=0; % Number of bit errors to be accumulated for k=1:MaxIter i= ceil(rand*M); s=ss(i,:); % Signal index, Data bits to transmit for n=1:Ns % Operation per symbol time st=[st(2:LB) sw(i,n)]; % Uncontaminated received signal yn=suT*st(LBN1:LB)'; % Correlator output sample with no noise y=[y(:,2:LB) yn]; wct=wcT*(n-1); bp_noise= randn*cos(wct)-randn*sin(wct); r=[r(2:LB) sw(i,n)+sgmsT*bp_noise]; % Received signal yrn= suT*r(LBN1:LB)'; % Correlator output sample with noise yr=[yr(:,2:LB) yrn]; % noisy Correlator output buffer end % Detector(DTR) [yremax,lmax]= max(yrn); d=ss(lmax,:); % Detected data bits nobe=nobe+sum(s~=d); if nobe>100; break; end end pobe(iter)= nobe/(k*b); end subplot(221), plot(tt,st,'k', tt,r,'b:'), title('r(t)') subplot(222), plot(tt,y(1,:),'k', tt,yr(1,:),'b:'), hold on plot([1:4]*Tb-T,yr(1,[1:4] *Ns),'+'), title('Correlator 0 output') subplot(224), plot(tt,y(2,:),'k', tt,yr(2,:),'b:'), hold on plot([1:4]*Tb-T,yr(2,[1:4] *Ns),'+'), title('Correlator 1 output') subplot(223), semilogy(SNRbdBt,pobet,'k-', SNRdBs,pobe,'b*') title('Bit Error Probability for coherent binary FSK Signaling')