資源簡(jiǎn)介
在GPS接收機(jī)中,捕獲到衛(wèi)星信號(hào)并對(duì)C/A碼進(jìn)行跟蹤是研制GPS接收機(jī)的重要問(wèn)題之一。以MATLAB為平臺(tái)實(shí)現(xiàn)這個(gè)捕獲總模塊,對(duì)算法進(jìn)行設(shè)計(jì)及優(yōu)化后,給出了相應(yīng)的仿真。 主要是對(duì)C/A碼的生成原理及其特性、GPS信號(hào)的形式及生成原理進(jìn)行了深入地分析,并對(duì)GPS信號(hào)的捕獲機(jī)理進(jìn)行詳細(xì)地闡述。在進(jìn)行碼捕獲時(shí),將偽碼剝離,便于實(shí)現(xiàn)GPS的解擴(kuò)過(guò)程。主要是通過(guò) MATLAB編程工具模擬GPS信號(hào),然后實(shí)現(xiàn)信號(hào)捕獲。 有實(shí)驗(yàn)結(jié)果 以及結(jié)果分析 還有 CA碼的產(chǎn)生流程圖
代碼片段和文件信息
function?acqResults?=?acquisition(longSignal?settings)
%Function?performs?cold?start?acquisition?on?the?collected?“data“.?It
%searches?for?GPS?signals?of?all?satellites?which?are?listed?in?field
%“acqSatelliteList“?in?the?settings?structure.?Function?saves?code?phase
%and?frequency?of?the?detected?signals?in?the?“acqResults“?structure.
%
%acqResults?=?acquisition(longSignal?settings)
%
%???Inputs:
%???????longSignal????-?11?ms?of?raw?signal?from?the?front-end?
%???????settings??????-?Receiver?settings.?Provides?information?about
%???????????????????????sampling?and?intermediate?frequencies?and?other
%???????????????????????parameters?including?the?list?of?the?satellites?to
%???????????????????????be?acquired.
%???Outputs:
%???????acqResults????-?Function?saves?code?phases?and?frequencies?of?the?
%???????????????????????detected?signals?in?the?“acqResults“?structure.?The
%???????????????????????field?“carrFreq“?is?set?to?0?if?the?signal?is?not
%???????????????????????detected?for?the?given?PRN?number.?
??
%--------------------------------------------------------------------------
%???????????????????????????SoftGNSS?v3.0
%?
%?Copyright?(C)?Darius?Plausinaitis?and?Dennis?M.?Akos
%?Written?by?Darius?Plausinaitis?and?Dennis?M.?Akos
%?based?on?Peter?Rinder?and?Nicolaj?Bertelsen
%--------------------------------------------------------------------------
%This?program?is?free?software;?you?can?redistribute?it?and/or
%modify?it?under?the?terms?of?the?GNU?General?Public?License
%as?published?by?the?Free?Software?Foundation;?either?version?2
%of?the?License?or?(at?your?option)?any?later?version.
%
%This?program?is?distributed?in?the?hope?that?it?will?be?useful
%but?WITHOUT?ANY?WARRANTY;?without?even?the?implied?warranty?of
%MERCHANTABILITY?or?FITNESS?FOR?A?PARTICULAR?PURPOSE.??See?the
%GNU?General?Public?License?for?more?details.
%
%You?should?have?received?a?copy?of?the?GNU?General?Public?License
%along?with?this?program;?if?not?write?to?the?Free?Software
%Foundation?Inc.?51?Franklin?Street?Fifth?Floor?Boston?MA??02110-1301
%USA.
%--------------------------------------------------------------------------
?
%CVS?record:
%$Id:?acquisition.mv?1.1.2.12?2006/08/14?12:08:03?dpl?Exp?$
?
%%?Initialization?=========================================================
?
%?Find?number?of?samples?per?spreading?code
samplesPerCode?=?round(settings.samplingFreq?/?...
????????????????????????(settings.codeFreqBasis?/?settings.codeLength));
?
%?Create?two?1msec?vectors?of?data?to?correlate?with?and?one?with?zero?DC
signal1?=?longSignal(1?:?samplesPerCode);
signal2?=?longSignal(samplesPerCode+1?:?2*samplesPerCode);
?
signal0DC?=?longSignal?-?mean(longSignal);?
?
%?Find?sampling?period
ts?=?1?/?settings.samplingFreq;
?
%?Find?phase?points?of?the?local?carrier?wave?
phasePoints?=?(0?:?(samplesPerCode-1))?*?2?*?pi?*?ts;
?
%?Number?of?the?frequency?bins?for?the?given?acquisition?band?(500Hz?steps)
numbe
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