Performance analysis of ISKANDARnet: a research-based network RTK positioning system

Abstract

GNSS positioning within the equatorial region suffers from distance-dependent errors due to severe atmospheric delays, which results in difficulty for the network ambiguity resolution process. Hence, it is a challenge to maintain the capability of centimetre-level positioning in this region. Subsequently, a network of Continuously Operating Reference Stations (CORS) situated in the developing region of Iskandar Malaysia, known as ISKANDARnet, has been developed by Universiti Teknologi Malaysia (UTM) as a research platform to support academic activities and high-precision positioning applications. The ISKANDARnet with its Network-based Real-Time Kinematic (N-RTK) technique provides a means to meet the challenge. In this study, the performance of ISKANDARnet N-RTK has been analysed in terms of positional accuracy, performance of ambiguity resolution, and effectiveness of network corrections by conducting real-world-scenario tests: (i) at different user locations, (ii) in varied observation sessions, and (iii) by external assessment with the national commercial N-RTK system, i.e., the Malaysia Real-Time Kinematic GNSS Network (MyRTKnet). The results indicated that significant changes in ambiguity resolution occur at different user locations and observation sessions, providing insight into the varying distance-dependent errors. Moreover, the positioning accuracy agrees to within centimetre-level of the national commercial N-RTK system.