Instantaneous cycle-slip correction for real-time PPP applications

Real-time precise point positioning (PPP) is limited to only a few applications using a moving receiver because the quality of the solution is vulnerable to interruptions in signal tracking. A loss of lock on all GPS signals simultaneously implies that users may have to wait for several minutes before again obtaining cmlevel precision. To avoid such a scenario, this paper proposes a method to instantaneously mitigate the impacts of signal interruptions and the resulting cycle slips. The approach is based on a time-differenced solution that allows for estimating the size of cycle slips in a least-squares adjustment. Once cycle slips are corrected, the PPP filter can be modified accordingly so as to prevent the occurrence of discontinuities in the positioning time series. The usefulness of the approach is demonstrated in selected applications such as geodynamics and car navigation.