Preliminary performance analysis of a prototype DFMC SBAS service over Australia and Asia-Pacific

Abstract

The next-generation of satellite-based augmentation system (SBAS) will employ a dual-frequency multi-constellation (DFMC) service providing several advantages over the classical SBAS L1 service. In September 2017, a two-year SBAS test-bed was initiated by Australia and New Zealand in preparation for building an operational system. This system includes DFMC SBAS in addition to the legacy SBAS L1 service and real-time precise point positioning (PPP) service over the Asia-Pacific region. In this paper, we focus on the new DFMC SBAS, and first discuss its positioning and integrity monitoring (IM) algorithms. Next, its performance is tested and analyzed using real DFMC SBAS data, restricting focus to LPV-200 in aviation. Based on real SBAS messages from the geostationary (GEO) satellite Inmarsat-4F1, testing was performed first at two known stations with actual GNSS observations, and next at simulated grids covering the entire Asia-Pacific region. A sensitivity analysis is performed, investigating the contribution of the error sources and the impact of changing the satellite mask angle. Experimental results of 12 consecutive days from September 14 to 25, 2018 of the new SBAS products show that the dual-frequency correction (DFC) residual errors have the dominant contribution in the values of the protection levels needed in IM, whereas other error sources such as the airborne receiver errors, the tropospheric and the ionosphere residual errors have secondary impacts. The accuracy of the positions was found to be at the sub-meter to meter level and was always bounded by the protection levels (PLs) at the known stations. The simulated PLs were less than the alert limit of LPV-200 during the test period in most of the areas of interest, indicating the availability of IM using DFMC SBAS in the main areas of the Asia-pacific region.