Advanced monitoring technique to strengthen the performance of marine DGPS

Abstract

The Differential Global Positioning System (DGPS) provides the means to improve the accuracy of GPS and to provide integrity monitoring for maritime users. DGPS provides real-time differential corrections for GPS signals and also monitors the integrity of the corrections. International organizations, including the International Maritime Organization (MO), the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA), and the Radio Technical Commission for Maritime Service (RTCM), have emphasized the role of DGPS as a national integrity assurance system. A set of Reference Station/Integrity Monitor (RSIM) of DGPS is now in operation to provide integrity monitoring functions, such as for pseudo-range corrections (PRC) of satellites or for a position solution that has exceeded the protection limit. However, it is not possible to provide continuous DGPS service in case of satellite outage and anomaly. Because the integrity monitoring functions of current RSIM focus on simply the limit of PRCs broadcasting from the RS. Moreover, the current monitoring concept of RSIM is not sufficient to satisfy the minimum maritime user requirements for general navigation, because of considering only on the aspect of RS. Therefore, this paper presents an advanced monitoring technique to strengthen the performance of DGPS for the maritime users. Also includes, the limitations of the integrity monitoring functions of current DGPS are analyzed, and the DGPS Monitoring (DGPSM) platform is presented in order to address the limitations of the current integrity monitoring functions. The DGPSM platform is verified by using measurements gathered from previous abnormal conditions.