Abstract: FrequencydriftcausedbyoscillatorwillpollutecarrierphaseandDopplerfrequencyinGPSreceiver.Therefore,itisnecessarytomodeltheoscillatorerrorinthetrackingsystem.TheflickernoiseerrorofoscillatorcannotbeexactlymodeledinKalmansystem,whichcauseserrorsinthemodeloftraditionalKalmanbasedtrackingloop.Tosolvetheseproblems,thefrequencydomainmodelandnoisecovarianceofoscillatorwereanalyzed,andamethodofexactlymodellingtheflickernoiseintheKalmanbasedtrackingloopwasproposed.RealGPSsatellitedatawasprocessedbyusingthenewoscillatormodeltoverifythevalidity.

Key words: Trackingloop, Crystaloscillatornoise, Kalmanfiltering, Errormodeling, Globalpositioningsystem