Can Long-Range Single-Baseline RTK Provide Service in Shanghai Comparable to Network RTK?

Abstract

Traditionally, GPS real-time kinematic (RTK) technique can provide precise positioning for short baselines, and network-based RTK (NRTK) is much more effective than the single-baseline RTK (SRTK) stemming from its capability of precise positioning over the whole area covered by reference stations. However, NRTK needs to build and maintain the infrastructure of reference stations. With multi–global navigation satellite system (GNSS) multifrequency signals becoming available, one can extend the service radius of SRTK to a few tens to even a hundred kilometers. This paper investigates whether one can realize the precise positioning with SRTK instead of NRTK in a medium-sized city located in the midlatitude region, like Shanghai. Different positioning models of SRTK are introduced and compared to those of NRTK. The variety of experiments were designed with triple-frequency BeiDou data and dual-frequency GPS data. The results show that the positioning results of SRTK and NRTK are comparable, with both having centimeter-level accuracy except for the relatively longer convergence time of ambiguity fixing for SRTK when the baseline is longer than 50 km. It is therefore expected that long-range SRTK is able to provide positioning service comparable to NRTK in most cities like Shanghai, of medium size and at midlatitude. Such a research finding is promising for reducing the cost of establishing and maintaining infrastructure used in NRTK.