Satellite-based augmentation system (SBAS) is one of GNSS augmentation systems that improve accuracy and integrity for using at aviation. Conventional SBAS augments positioning using single frequency (L1 band) signal of single GNSS (GPS). Therefore, the positioning augmented by SBAS occasionally has problems that the accuracies and availabilities are decreased by serious ionospheric disturbance or the number of GPS satellites shortage. Against that background, next-generation SBAS standards have been discussed at the SBAS Interoperability Working Group. The new SBAS is called as DFMC (dual-frequency, multi-constellation) SBAS, since it augments positioning using L1 and L5 band signals of multi-constellation GNSSs. Then, we are developing DFMC-SBAS prototype system. In this paper, we report a status of our development for prototype DFMC-SBAS. This paper describes a development status and preliminary results of the prototype system. According to the results, the prototype system works effectively at whole of Japan area. 95% positioning errors are smaller than 0.86 m in horizontal, and smaller than 1.73 m in vertical. Positioning errors and protection levels tend to be getting worse at outer (northern and southern) area of Japan. It seems to be caused by locations of ground monitoring stations (GMS) and the number of augmented satellites. A performance of the prototype system is capable of LPV-200 procedure high-frequently. From the perspective of a ratio that the protection levels are under the alert limit, availability is 99.986% for LPV-200.
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