Ionosphere-Nullification Technique for Long-Baseline Real-Time Kinematic Applications

Abstract

ABSTRACT: One of the major challenges in resolving ambiguities for longer baselines is the presence of unmodeled ionospheric delays. In this paper, we describe a new ionospheric approach that does not rely on the convergence of an ionospheric parameter, and that instantaneously nullifies the effect of the differential ionospheric delay in the ambiguity search process. Although this approach was originally developed for single-baseline RTK over long distances in kinematic mode, it can be used for network RTK when requiring extrapolation of the differential ionospheric corrections for a rover located outside the network. It can also be used in cases where the rover located inside the network is experiencing a local anomaly in the differential ionospheric delays. The performance of the ionosphere-nullification technique was demonstrated on an approximately 74 km ferry route across the Bay of Fundy in eastern Canada. For both static and kinematic tests over the 74 km baseline, a few mm mean differences were observed in each Cartesian component, and the comparison 1s̀ noise level was at the few cm level.