www.gusucode.com > GPS仿真Matlab编程源码程序 > GPS仿真Matlab编程源码程序/acquisition_lj.m
function acqResults = acquisition_lj(x2,longSignal, settings,N)
%% Initialization ================================================
% Find number of samples per spreading code
% samplesPerCode = round(settings.samplingFreq / ...
% (settings.codeFreqBasis / settings.codeLength));
%--------------------------------------------------------------------------
% Initialize acqResults
% Carrier frequencies of detected signals
acqResults.carrFreq = zeros(1, 32);
%--------------------------------------------------------------------------
% C/A code phases of detected signals
acqResults.codePhase = zeros(1, 32);
%--------------------------------------------------------------------------
% Correlation peak ratios of the detected signals
acqResults.peakMetric = zeros(1, 32);
%--------------------------------------------------------------------------
delay=zeros(32, 4);
C=zeros(32, 4);
fdm=zeros(1,4);
num=zeros(1,4);
delay1=zeros(1,4);
% fprintf('(');
%CVS record:
%$Id: acquisition.m,v 1.1.2.12 2006/08/14 12:08:03 dpl Exp $
% N=settings.samplingFreq*280e-3;%0.05
% N1=settings.samplingFreq*1e-3;
N2=settings.samplingFreq*1e-3;
% cnt=N2/N1;
timebegin=0;
L=2^(nextpow2(N));
% L=N;
% L1=2^(nextpow2(N1));
L2=2^(nextpow2(N2));
% pxx=zeros(L2,1);
% yf=zeros(N2,1);
% timeend=N/settings.samplingFreq;
% timeend1=N1/settings.samplingFreq;
timeend2=N2/settings.samplingFreq;
% snr=-18; % dB
% As=10^(snr/20);
% zz=fft(longSignal-mean(longSignal));
% fftw('planner','patient')
zz=fft(longSignal(1:N2));
% longSignal=longSignal(1:N);
% cnt=600;
%% -------------FFT--------------%%%%%%
pxx=abs(fft(x2,L));
% index1=1e5;
for n=1:settings.numberOfChannels
[fftMax1, fftMaxIndex1] = max(pxx);
omiga1=(1-(fftMaxIndex1-1)/L)*2*pi;
fdm1(1)=(omiga1/2)*settings.samplingFreq/(2*pi);
fdm1(2)=(omiga1/2+pi)*settings.samplingFreq/(2*pi);
% fdm1(1)=(1-(fftMaxIndex1-1)/L)*0.5*settings.samplingFreq;
% [index1]= find(abs(fdm1-settings.IF)<10e3);
% in1=isempty(index1);
% if in1==1
fftMaxIndex2=L+4-fftMaxIndex1;
omiga1=(1-(fftMaxIndex2-1)/L)*2*pi;
fdm1(3)=(omiga1/2)*settings.samplingFreq/(2*pi);
fdm1(4)=(omiga1/2+pi)*settings.samplingFreq/(2*pi);
% fdm2=fdm1(3);
% fdm3=fdm1(4);
% index1=find(fdm1==fdm2);
% index2=find(fdm1==fdm3);
% fdm1(index1)=0;
% fdm1(index2)=0;
% end
% fdm1(2)=(1-(fftMaxIndex2-1)/L)*0.5*settings.samplingFreq;settings.samplingFreq-
[index]= find(abs(fdm1-settings.IF)<10e3);%|abs(fdm1-(settings.samplingFreq-settings.IF))<10e3
% if n==1
fdm(n)=fdm1(index);
% else
% fdm_tmp=fdm1(index);
% index2=find(fdm_tmp~=fdm(n));
% fdm(n)=fdm1(index2);
% end
% fdm1=0;
for dot=1:5
pxx(fftMaxIndex1-3+dot)=0;
pxx(L+4-fftMaxIndex1-3+dot)=0;
end
end
% f1=settings.IF-10e3;
% f2=settings.IF+10e3;
%
% f=f1:1e3:f2;
% xy=0;
% for f=f1:1e3:f2
% xy=xy+1;
% N2(xy)=ceil((1-f/settings.samplingFreq)*L+1);
% end
% px=zeros(1,length(f));
% for tx=1:length(f)
% temp=myfft_part(x2,f(tx),f(tx),settings.samplingFreq);
% px(tx)=max(abs(temp));
% end
% [a,b]=sort(px,'descend');
% for ii=1:settings.numberOfChannels
% f1=f(b(ii))-500;
% f2=f(b(ii))+500;
% pxx=abs(myfft_part(x2,f1,f2,settings.samplingFreq));
% [fftMax1, fftMaxIndex1] = max(pxx);
% fdm(ii)=(1-(fftMaxIndex1-1)/L)*0.5*settings.samplingFreq;
% end
%% ---------part FFT------------------%%%%%%
% f1=settings.IF-10e3;
% f2=settings.IF+10e3;
% pxx=abs(myfft_part(x2,f1,f2,settings.samplingFreq));
% for n=1:settings.numberOfChannels
% [fftMax1, fftMaxIndex1] = max(pxx);
% fdm(n)=(1-(fftMaxIndex1-1)/L)*0.5*settings.samplingFreq;
% for dot=1:5
% pxx(fftMaxIndex1-3+dot)=0;
% pxx(L+4-fftMaxIndex1-3+dot)=0;
% end
% end
%%%%%%---------Zoom FFT---------------%%%%%%%
% B=10e3;
% % complex modulated signal
% x1=x2.*exp(-1i*2*pi*[1:length(longSignal)]*(settings.samplingFreq-settings.IF*2)/settings.samplingFreq).';
% % Digital LPF
% om1=2*pi*(settings.IF-B)/settings.samplingFreq;
% om2=2*pi*(settings.IF+B)/settings.samplingFreq;
% D=floor(pi/(om2-om1));
% K=floor(om1*D/pi);
% while ((K+1)/D*pi<om2)
% D=D-1;
% K=floor(om1*D/pi);
% end
% % D=fs/20e3;
% bw=settings.samplingFreq/(2*D);b=fir1(32,2*bw/settings.samplingFreq);y=filter(b,1,x1);
% % resampling
% N3=2^16;
% N4=floor(N/D);
% yd=zeros(1,N4);
% for ii=1:N4
% yd(ii)=y(ii*D);
% end
% % zoomed spectrum
% pxx=abs(fft(yd,N3));
% for n=1:settings.numberOfChannels
% [fftMax1, fftMaxIndex] = max(pxx);
% if fftMaxIndex>=1 && fftMaxIndex<=N3/2-1
% fftMaxIndex1=fftMaxIndex+N3/2+1;
% else if fftMaxIndex>=N3/2 && fftMaxIndex<=N3-1
% fftMaxIndex1=fftMaxIndex-N3/2+1;
% else
% fdm(n)=0;
% end
% end
% fdm(n)=settings.IF-B+(fftMaxIndex1-1)*2*B/N3;
% for dot=1:5
% pxx(fftMaxIndex-5+dot)=0;
% % pxx(L+4-fftMaxIndex1-5+dot)=0;
% end
% end
t_sig1=timebegin:1/settings.samplingFreq:timebegin+timeend2-1/settings.samplingFreq;
% t_sig=timebegin:1/settings.samplingFreq:timebegin+timeend1-1/settings.samplingFreq;
caCodesTable = makeCaTable(settings);
for m=1:32
% sg=signalgen1(m,timebegin,settings.samplingFreq,timeend2,0,settings.codeFreqBasis);
sg = caCodesTable(m,:);
for n=1:settings.numberOfChannels
% s=As*signalgen(m,timebegin,settings.samplingFreq,timeend2,0,fdm(n),settings.codeFreqBasis);
% s=fft(s).';
% y1=conj(s).*zz(1:N2);
% y2=abs(fft(y1,L2));
% [B,k]=max(y2);%(1:uniqFftPt-1));
% omiga2=(1-(k-1)/L2)*2*pi;
% omiga2=mod(omiga2,settings.samplingFreq*2*pi*1e-3/N);
% or=settings.samplingFreq*2*pi*0.714518*1e-3/N;
%
% Z=zeros(L2-N2,1);
% yt=[y1;Z];
% fun=@(omigam) -abs((exp(-1j*(0:L2-1)*omigam)*yt).');
% omiga(1)=fminbnd(fun,omiga2-2*pi/L2,omiga2+2*pi/L2);
%
% delay(m,n)=omiga(1)*N2/(2*pi*settings.samplingFreq)*1e3;
s=sg.*exp(1i*2*pi*fdm(n)*t_sig1);
% s2=As*signalgen(m,timebegin,settings.samplingFreq,timeend2,0,fdm(n),settings.codeFreqBasis);
s=fft(s).';
% for h=1:cnt
% sf(:,h)=s(N1*(h-1)+1:N1*h);
% % sf(:,h)=s;
% yf(:,h)=zz(N1*(h-1)+1:N1*h);
% temp(:,h)=abs(fft(conj(sf(:,h)).*yf(:,h),L1));
% end
% temps=sum(temp,2);
% [B,k]=max(temps);
% omiga2=(1-(k-1)/L1)*2*pi;
%
% omiga2=mod(omiga2,settings.samplingFreq*2*pi*1e-3/N1);
%
% omiga(1)=omiga2;
%
% delay(m,n)=omiga(1)*N1/(2*pi*settings.samplingFreq)*1e3;
y1=conj(s).*zz;
y2=abs(fft(y1,L2));
[B,k]=max(y2);%(1:uniqFftPt-1));
omiga1=(1-(k-1)/L2)*2*pi;
omiga2=mod(omiga1,settings.samplingFreq*2*pi*1e-3/N2);
delay(m,n)=omiga2*N2/(2*pi*settings.samplingFreq)*1e3;
C(m,n)=B;
end
end
for n=1:settings.numberOfChannels
[peak(n),num(n)]=max(C(:,n));
if n>1
k1=find(num(1:n-1)==num(n));
if k1~=0
if peak(k1)<peak(n)
C(num(n),n)=0;
[peak(n),num(n)]=max(C(:,n));
else
C(num(k1),k1)=0;
[peak(n),num(k1)]=max(C(:,k1));
end
end
end
end
acqResults.peakMetric(num) = peak;
acqResults.carrFreq(num) = fdm;
for ii=1:length(num)
delay1(ii)=delay(num(ii),ii);
end
acqResults.codePhase(num) = round(delay1*N2);
% for n=1:settings.numberOfChannels
% [peak(n),num(n)]=max(max(C));
% [peak(n),sat(n)]=max(max(C, [], 2));
% C(:,num(n))=0;
% C(sat(n),:)=0;
% end
%
% acqResults.peakMetric(sat) = peak;
% acqResults.carrFreq(sat) = fdm;
% for ii=1:length(sat)
% delay1(ii)=delay(sat(ii),ii);
% end
% acqResults.codePhase(sat) = round(delay1*N2);