Performance Analysis of the QZSS SIS-URE and User Positioning Accuracy with GPS and QZSS

摘要

QZSS (Quasi-Zenith Satellite System) is a Japanese spacebased PNT (Positioning, Navigation and Timing) system,which is being developed aiming at augmenting GPS inJapan and surrounding area. The development of QZSS isbeing implemented with step by step manner. As first step,the first satellite called as QZS-1 is to be launched in JFY(Japanese Fiscal Year) 2009 and technical validation anddemonstrations of various applications will be carried outduring one year demonstration period. The developmentof QZS-1 is being processed steadily. CDRs (CriticalDesign Review) for some of subsystems of the satellitebus were held in January, 2008 following Navigationsystem’s CDR ended in 2007. The manufacturing of PFM(Proto Flight Model) of NP (Navigation Payload) andprocurements of components for bus system have alreadystarted. The performance analysis of the QZSS SIS-URE(Signal in Space - User Range Error) and user positioningerror for combining usage of QZSS and GPS wasperformed for the CDR of Navigation system. All errorsources of PR (Pseudo Range) in the error budget,categorized into SIS-URE, propagation error and UEE(User Equipment Error), were evaluated by simulationand analysis. From the objective of this study, SIS-UREincluding errors coming from interoperability with GPSand ionospheric delay correction error are emphasized inthis paper, since these errors are made corrections byusing parameters which provided by QZSS, i.e. dependingon the system performance of QZSS. Other error sources,tropospheric delay correction error, multipath andreceiver noise are explained in short description. Theevaluated error budget was used for the analysis of SISUREand user positioning error in order to verify theQZSS Navigation system design. The result of analysisshowed that the performance of QZSS Navigation systemwould surely meet its specification.