Design of RSIM Architecture for Performance Enhancement of Maritime DGPS

Abstract

Recently, the U.S. Coast Guard (USCG) and partner agencies are looking to modernize Differential Global Position System (DGPS). The modernization potentials include not only GPS receiver technology, but also networking technologies, new GPS signals, possible data compression techniques and correction information generation techniques, all of which are aimed at providing the end-user with improved capabilities (accuracy, integrity, continuity, and availability). The USCG has identified a need to re-capitalize the Reference Station (RS) and Integrity Monitor (IM) equipment used in the DGPS. As a result, the scheme in preparing for the future DGPS is to port current RTCM SC-104 compatible RS and IM functionality onto an open architecture PC-based platform. However, their scheme lacks the open architecture required to include future system improvements such as use of new civil frequencies on L2 and L5 and realization of a higher rate NDGPS beacon data channel intended to support RTK and upcoming Galileo if possible and function of integrity monitor for abnormal GNSS signals. To solve this apprehension, this paper proposes a hybrid SDR (software defined radio)-based software architecture for DGPS Reference Station (RS) and Integrity Monitor (IM) modernization. The proposed architecture includes a hybrid SDR-based GPS receiver instead of available off-the-shelf hardware GPS receiver. The hybrid SDR-based GPS receiver has no need to change the hardware in the case of adapting the advanced algorithms or processing schemes to another system such as Galileo and GLONASS. It has the benefits of flexibility and reconstruction, which are weak points of the off-the-shelf GPS receiver implemented by hardware. This paper will present promising architecture for the next generation DGPS RS and IM. This paper will show that the presented architecture has not only a hybrid SDR-based receiver functionality, but also functional operation for RS and IM, and it will show that this architect