Analysis on the Limitation of Integrity Monitoring Function for Maritime DGPS

Abstract

Current Differential GPS RSIM system consists of Reference Station (RS), Integrity Monitor (IM), and Control Station (CS). The RS uses a reference receiver and an MSK modulator to generate the RTCM messages for broadcasting, and the IM receives the RS broadcast and verifies that the information is within tolerance. The function of integrity monitor is very important to prepare for the function upgrade of GNSS augmentation system and Differential GNSS recapitalization. The current regulation related to DGPS RSIM is presented in RTCM standard 10401.2. However the current algorithms for integrity monitoring have been presented the limitations of integrity monitoring function for satellite outage or anomaly. Therefore this paper focuses on the limitation of integrity monitoring for maritime DGPS. Firstly, it analyzes the functionality of maritime DGPS integrity monitoring and the key components for generation of IM information, and the limitation of IM functions. And it then presents the limitation of IM function based on the real case of satellite anomaly.