Matlab Simulation Toolset for SBAS Availability Analysis

This paper describes a set of MATLAB functions currently being developed for SBAS availability analysis. This toolset includes simulation algorithms that are constantly being developed and updated by various working groups. This set of functions is intended for use as a fast, accurate, and highly customizable experimental test bed for algorithm development. A user-friendly interface has also been developed for the tool. It is open source and can be downloaded from Stanford WAAS web site (http://waas.stanford.edu). Therefore, it provides a common ground for different working groups to compare their results. There are four major components of this service volume analysis toolset: confidence computation, simulation configurations, outputs, and the graphic user interface. Algorithms currently implemented for confidence computation of UDRE, GIVE, troposphere, and airborne corrections are used in the tool. Users can also readily modify parameters of the algorithms or include custom algorithms they wish to test. Simulations can be configured to modify the WAAS reference station (WRS) network, user locations, satellite constellation, and ionospheric grid point (IGP) mask as well. The outputs of the toolset include plots of availability, protection levels, UDRE and GIVE maps and histograms. The toolset includes a graphic user interface, which allows the user to specify different options for the simulation very quickly and easily. In this paper, we demonstrate the utility of this toolset by analyzing the SBAS service volume models for CONUS for a change to the GIVE algorithm. We also simulate a case where vertical troposphere error is reduced. The results show this toolset is valuable for investigating how the algorithms impact availability.