%?％程序捕獲代碼部分
function?acquisitionAll（x）
%?Performs?a?cold?start?acquisition?on?the?collected?data?x
%?Searches?through?all?satellites
%?Returns?the?code?phase?and?the?coarse?frequency?of?the?signal

%?*****?initial?conditions?*****
global?gold?%?Gold?codes
global?settings?%?The?Settings?of?the?recevier
global?channel?%?The?Settings?of?the?channels
fs=11.999e6;?%?sampling?freq
ts=1/fs;?%?sampling?time
n=fs/1000;?%?data?pt?in?l?ms
nn=[0:n-1];?%?total?no.?of?pts
if_freq=3563000;%?Intermediate?frequency;
%if_freq=0;%?Intermediate?frequency;

%?for?svnum=1:32
for?svnum=2
????fprintf（‘.‘）;
????frequency?=?0;
????codephase?=?0;

%?*****?DFT?of?C/A?code?*****
codefreq?=?conj（fft（gold（svnum:）））;

xxxx=zeros（4111999）;
for?mmmmm=1:100?????%非相干100次
????for?i=1:41
????fc（i）?=?3.553e6?+?0.0005e6*（i-1）;
????%for?i=1:21??%?for?if_freq=0
????%fc（i）?=?0+500*（i-1）;
????expfreq=exp（j*2*pi*fc（i）*ts*nn）;
????sine=?imag（expfreq）;?%?generate?local?sine
????cosine=?real（expfreq）;?%?generate?local?cosine
????I?=?sine.*x‘;
????Q?=?cosine.*x‘;
????IQfreq?=?fft（I+j*Q）;
????convcodeIQ?=?IQfreq?.*?codefreq;
????result（i:）?=?abs（ifft（convcodeIQ））.^2;
????xxxx（i:）=xxxx（i:）+result（i:）;
????end
end
figure（1）
mesh（result）
figure（2）
mesh（xxxx）

[peak?codephase]=max（max（result））;
[peak?frequency]=max（max（result‘））;
result_noise=result;
result_noise（:codephase）=[];
result_noise（frequency:）=[];
meanValue?=?mean（mean（result_noise））;
meanPeak?=?peak/meanValue

if?meanPeak>15.9
%?*****?Search?for?fine?resolution?frequency?*****
ncodephase?=?n?-?codephase;
code?=?[gold（svnumncodephase:n）?gold（svnum1:ncodephase-1）];
xcarrier?=?x‘.*code;
for?i=1:11
fc_fine（i）?=?fc（frequency）?+?（i-6）*100;
if?fc_fine（i）?fc_fine（i）?=?0;
end
expfreq=exp（j*2*pi*fc_fine（i）*ts*nn）;
sine=?imag（expfreq）;?%?generate?local?sine
cosine=?real（expfreq）;?%?generate?local?cosine
I?=?sine.*xcarrier;
Q?=?cosine.*xcarrier;
result_fine（i:）=sum（I‘）.^2+sum（Q‘）.^2;
end
%[peak?codephase1]=max（max（result_fine））;
%[peak?frequency]=max（max（result_fine‘））;
%result_noise=result_fine;
%result_noise（:codephase1）=[];
%result_noise（frequency:）=[];
%meanValue?=?mean（mean（result_noise））;
%meanPeak?=?peak/meanValue;
[peak?frequency]=max（result_fine‘）;
result_noise=result_fine;
result_noise（frequency）=[];
%meanValue?=?mean（result_noise）;
%meanPeak?=?peak/meanValue;
frequency?=?fc_fine（frequency）;

%?*****?Setup?a?channel?for?the?satellite?*****
channel（settings.nextChannel）.SVN=svnum;
channel（settings.nextChannel）.AcqFreq=frequency;
channel（settings.nextChannel）.Doppler=frequency-if_freq;
channel（settings.nextChannel）.AcqCAPhase=mod（ncodephasen）;?%?phase?means?end?phase?of?gold?code
channel（settings.nextChannel）.Status=‘P‘;
settings.nextChannel=settings.nextChannel+1;
end
end

?屬性????????????大小?????日期????時(shí)間???名稱(chēng)
-----------?---------??----------?-----??----

?????文件???????2851??2010-11-05?20:54??gps_lunwen\acquisitionAll.m

?????文件????????314??2010-11-02?19:12??gps_lunwen\calculatePLLCoef.m

?????文件???????1321??2010-11-02?19:15??gps_lunwen\decodeNavigation.m

?????文件???????1040??2010-11-02?21:38??gps_lunwen\GPS_shixiong.m

?????文件????????532??2010-11-02?23:03??gps_lunwen\init.asv

?????文件????????532??2010-11-02?23:04??gps_lunwen\init.m

?????文件????????668??2010-11-02?19:16??gps_lunwen\ShowChannelStatus.m

?????文件???????4664??2010-11-02?19:15??gps_lunwen\tracking.m

?????目錄??????????0??2010-11-06?10:26??gps_lunwen

-----------?---------??----------?-----??----

????????????????11922????????????????????9