Timevarying Property of Narrowlane Uncalibrated Phase Delays Products Estimated from a Global Reference Station Network

Abstract:

The quality and availability of narrowlane (NL) uncalibrated phase delays (UPD) products are the key factors to precise point positioning ambiguity resolution (PPPAR) service. In this paper, the GPS observations from 108 world distributed International GPS Service (IGS) reference stations were employed to calculate the widelane (WL) and NL UPD products. The variations of NL UPDs were evaluated and the results show that the maximum daily variation can reach 0.6 cycles. Then, the residuals of ambiguities corrected with UPDs were analyzed to demonstrate that ambiguities and UPDs are both influenced by the unmodeled atmosphere errors. We found the timevarying property of NL UPD is relevant to the residual atmospheric errors of the selected reference stations used to estimate UPDs. Moreover, the real observation data of four IGS stations were processed in PPPAR mode to demonstrate the time availability of UPD products. The statistical results of timetofirstfix (TTFF), unfix rate and incorrect fix rate were adopted to evaluate the performance of PPPAR service. According to the experiment results, we concluded that the effective time limit of NL UPD products should be no more than 30 minutes.