Implementation of Prototype Satellite-Based Augmentation System (SBAS)

The SBAS, satellite-based augmentation system, is basically the wide-area differential GPS (WADGPS) effective for numerous users within continental service area. For a practical investigation of wide-area augmentation technique, the authors have implemented the prototype system of the SBAS. It has achieved positioning accuracy of 0.3 to 0.6 meter in horizontal and 0.4 to 0.8 meter in vertical, respectively, over mainland of Japan during nominal ionospheric conditions with only 6 monitor stations. The historical severe ionospheric activities might disturb and degrade the positioning performance to 2 meters and 3 meters for horizontal and vertical, respectively. In all cases, it has been shown that both horizontal and vertical protection levels have never been exceeded by the associate position errors regardless of ionospheric activities.