matlab_随机信号的自相关函数和互相关函数

clc;clear all;close all; %% 'Barker, 13 elements' % r=10;% signal is sampled r times in each tb (r/tb sampling rate) % u_amp=ones(1,13);% signal amplitude vector % u_phase=[0 0 0 0 0 1 1 0 0 1 0 1 0];% signal phase vector % u = [ones(1,r*5),-(ones(1,r*2)),ones(1,r*2),-ones(1,r),ones(1,r),-ones(1,r),ones(1,r)];%13 bit % df=.0308; % K=50;% number of points in the Doppler axis for ambiguity plot is K %% 'Frank,P1,P2, M elements' % r=10;% signal is sampled r times in each tb (r/tb sampling rate) % M=8; % u_amp=ones(1,M*M);% signal amplitude vector % for i=1:M % for j=1:M % % phi(j,i)=2*pi/M*(i-1)*(j-1);% 'Frank, M elements' % phi(j,i)= (-pi/M/2)*(2*i-1-M)*(2*j-1-M);% 'P2, M elements' % % phi(j,i)= (-pi/M)*(M-(2*j-1))*((j-1)*M+(i-1));% 'P1, M elements' % end % end % nn=0; % for ii=1:M % for jj=1:M % nn=nn+1; % phi2(nn)=phi(ii,jj); % end % end % j=sqrt(-1); % u_phase=phi2; % u_basic=u_amp.*exp(j*u_phase); % m_basic=length(u_basic); % ud=diag(u_basic); % ao=ones(r,m_basic); % m=m_basic*r; % u=reshape(ao*ud,1,m); % u_basic with each eleement repeated r times % df=.0312;% maximal displayed Doppler is F/Mtb K=50;% number of points in the Doppler axis for ambiguity plot is K %% 'P3,P4, M elements' % r=10;% signal is sampled r times in each tb (r/tb sampling rate) % M=64; % u_amp=ones(1,M);% signal amplitude vector % for i=1:M % % phi(i)= (pi/M)*(i-1)*(i-1);% 'P3, M elements' % phi(i)= (pi/M)*(i-1)*(i-1)-pi*(i-1);%'P4, M elements' % end % j=sqrt(-1); % u_phase=phi; % u_basic=u_amp.*exp(j*u_phase); % m_basic=length(u_basic); % ud=diag(u_basic); % ao=ones(r,m_basic); % m=m_basic*r; % u=reshape(ao*ud,1,m); % u_basic with each eleement repeated r times % df=.0312;% maximal displayed Doppler is F/Mtb % K=50;% number of points in the Doppler axis for ambiguity plot is K %% 'T1,T2,T3,T4' r=1; m=2; k=4; T=16e-3; ttt=1; deltaf=1e3; for tt = linspace(0,T,120); jj = floor(k*tt/T); % phase(ttt)= mod(((2*pi/m)*floor(((k*tt - jj*T)*(jj*m/T)))), 2*pi); % T1 % phase(ttt)= mod(((2*pi/m)*floor((((k*tt - jj*T)*((2*jj-k+1)/T)*(m/2))))), 2*pi); % T2 % phase(ttt)=mod(((2*pi/m)*floor((m*deltaf*tt.^2)/(2*T))),2*pi); % T3 phase(ttt)=mod(((2*pi/m)*floor((m*deltaf*tt.^2)/(2*T)-(m*deltaf*tt)/2)),2*pi); % T4 if ttt==1 phaseunwrapped(ttt)=phase(ttt); else if phase(ttt)==phase(ttt-1) phaseunwrapped(ttt)=phaseunwrapped(ttt-1); else phaseunwrapped(ttt)=phaseunwrapped(ttt-1)+2*pi/m; end end ttt= ttt+1; end u=exp(j*phase); u_amp=ones(1,length(u)); df=.0312;% maximal displayed Doppler is F/Mtb K=50;% number of points in the Doppler axis for ambiguity plot is K %% 'LFM ' % r=1; % dt=1; % u_amp=ones(1,51); % u_freq=.0031*[-25:25]; % df=.0032; % K=60; % phas=2*pi*dt*cumsum(u_freq); % % phas=2*pi*(-.0031*25*[0:50]*dt+0.5*.0031*[0:50].^2*dt.^2); % u=exp(j*phas); %% F=df*length(u_amp)*K; scalet=[0:length(u)-1]/r; % calcualte normalized ACF acfun=20*log10(abs(xcorr(u))+eps); acfun=acfun-max(acfun); acfun1=acfun; acfun=max(acfun,-70); acfun=acfun(length(u):2*length(u)-1); % acfun=acfun(1:(length(acfun)+1)/2); % acfun=fliplr(acfun); % calcualte normalized PACF zeru=zeros(size(u)); pacfun=20*log10(abs(xcorr([u u u],[zeru u zeru]))+eps); % clear zeru; pacfun=pacfun-max(pacfun); pacfun=max(pacfun,-70); pacfun=pacfun(3*length(u):4*length(u)-1); % calcualte spectrum % fftlength=max(1024*8,length(u)*32); % spec=20*log10(max(abs(fft(u,fftlength)),eps)); % spec=spec-max(spec); % spec=max(spec,-60); % spec=spec(1:fftlength/2); % scales=[0:fftlength/2-1]/(fftlength/2-1)*r/2; figure(1) plot(scalet,acfun,'k'); xlabel('{\it\tau}/\itt_b');ylabel('[dB]'); title('Autocorrelation'); axis([0 max(scalet) -70 0]); grid on; figure(2) plot(scalet,pacfun,'r','linewidth',2); xlabel('{\it\tau}/\itt_b'); ylabel('[dB]'); title('Periodic Autocorrelation '); axis([0 max(scalet) -70 0]); grid on; % subplot(313); % plot(scales*length(u)/r,spec,'k'); % xlabel('{\itf*Mt_b}'); % ylabel('|{\itS}({\itf})|'); % axis([0 F -60 0]); % grid on;