Investigation of network-based RTK techniques: a case study in urban area

Abstract

Network-based real-time kinematic (NRTK) GNSS (Global Navigation Satellite System) positioning system is one of the most commonly used in many countries for various applications which require instant and highly accurate positioning all around the clock. The main principle of this system is to generate reliable error models that can mitigate dispersive (e.g., ionospheric delay) and non-dispersive (e.g., tropospheric delay and orbit biases) errors which are the main sources for the degradation of the positioning accuracy. There are several correction techniques that have been implemented and used in NRTK concept. The objective of this study is to evaluate accuracy, precision, time to first fix (TTFF), and performance of carrier phase ambiguity fixing while maintaining the same survey conditions for VRS, FKP, and MAC NRTK techniques. The Turkish TUSAGA-Aktif CORS network was used to obtain the three NRTK corrections. In terms of accuracy, our results show that all the techniques are practically the same and the horizontal positioning accuracy is in the order of few centimeters for all techniques. As far as precision and TTFF are concerned, VRS produced slightly better results comparing to the others. When it comes to ambiguity fixing performance in the dynamic environment, FKP produced the best results.