基于批处理与差分相干的GPS信号捕获算法.docx

基于批处理与差分相干的GPS信号捕获算法
基于批处理与差分相干的GPS信号捕获算法
摘要
GPS信号的捕获是导航应用的关键步骤之一。本文提出了一种基于批处理和差分相干的GPS信号捕获算法。该算法包括批处理预处理、差分相干测量、周期性搜索和峰值检测等几个步骤。其中，批处理预处理模块对接收信号进行幅度平滑和相位去跳处理，差分相干测量模块可有效地抑制信号的多普勒频移和多径效应，周期性搜索模块可以降低计算量，峰值检测模块可提高算法的鲁棒性。实验结果表明，该算法可以在保证高正确性和高灵敏度的同时，实现较低的计算复杂度和较短的信号捕获时间。
关键词：GPS信号捕获；批处理；差分相干；周期性搜索；峰值检测
Introduction
GlobalPositioningSystem(GPS)hasbecomeoneofthemostimportanttechnologiesinnavigationapplications.TheGPSreceiverneedstocapturetheGPSsignalstransmittedfrommultiplesatellitesinordertocalculatethereceiver'sposition.SignalacquisitionisoneofthekeystepsintheGPSreceiver.ThesignalacquisitionprocessincludessearchingandidentifyingtheGPSsignalsinthereceivedsignal,andthenestablishingsynchronizationwiththeGPSsignals.Ahigh-performancesignalacquisitionalgorithmcansignificantlyimprovethenavigationaccuracyandpositioningspeedoftheGPSreceiver.
Inrecentyears,manysignalacquisitionalgorithmsforGPShavebeenproposed.ThemostwidelyusedalgorithmistheFastFourierTransform(FFT)basedalgorithm.Inthisalgorithm,theincomingsignalisprocessedusingFFT,andthepeaksinthefrequencydomainareusedtoidentifytheGPSsignal.Althoughthisalgorithmhasgoodperformance,itsuffersfromhighcomputationalcomplexityandlongacquisitiontime.
Inthispaper,weproposeanewGPSsignalacquisitionalgorithmbasedonbatchprocessinganddifferentialcoherentmeasurement.Thisalgorithmincludesseveralsteps,suchasbatchprocessingpreprocessing,differentialcoherentmeasurement,periodicsearch,andpeakdetection.Theadvantagesoftheproposedalgorithmarelowcomputationalcomplexity,shortacquisitiontime,andhighaccuracy.
BatchProcessingPreprocessing
Batchprocessingpreprocessingisacriticalstepintheproposedalgorithm.Inthisstep,thereceivedsignalisfirstsampled,andthentheamplitudesmoothingandphaseunwrappingareperformedtoreducethenoiseandphaseerrorsinthesignal.Theamplitudesmoothingcanberealizedbyaveragingtheamplitudeofseveralconsecutivesamples.Thephaseunwrappingcanberealizedbycomparingthephasesoftwoadjacentsamplesandcorrectingthephasejumpbymultiplesof2π.
DifferentialCoheren