Phase clock/bias estimation for GNSS all-frequency undifferenced ambi-guity resolution
Undifferenced ambiguity resolution is a crucial technology for GNSS precision point positioning(PPP).The conven-tional PPP method typically uses ionosphere-free combination observations on the specific baseline frequencies(e.g.,GPS L1/L2).Therefore,the satellite clock and phase bias products required for ambiguity resolution(AR)are bounded to these speci-fied observation models and signal frequencies,which significantly limits the user's choice.To meet the user's demand for high-precision positioning with free choice of signal frequencies,this paper proposes an estimation method of"all-frequency phase clock/bias",which employs the undifferenced integer ambiguity constraints on the network processing to estimate phase clock and observable-specific signal bias(OSB)products.While ensuring their consistency with the datum of IGS(International GNSS Service)legacy clock and bias,these products enable the PPP ambiguity resolution applicable to arbitrary observation model and frequency choices.Both a 31-day test on 197 IGS MGEX(multi-GNSS experiment)stations and a kinematic test on car-borne data demonstrate that the GPS/Galileo/BDS all-frequency phase clock/bias product proposed by this paper maintains relatively consistent ambiguity resolution efficiency and static/kinematic positioning accuracy over any frequency combination in PPP-AR.In particular,we emphasize that the undifferenced integer ambiguity constraint applied to the network processing plays a vital role in guaranteeing the strict coupling of the satellite phase clock/bias products,which is essential to ensure the capability of all-frequency undifferenced ambiguity resolution.The all-frequency phase clock/bias products from Wuhan Uni-versity(ftp://igs.gnsswhu.cn/pub/whu/phasebias/)have been released since 2023 as a rapid routine service.
万方数据
维普
