Calculation of Accuracy and Integrity Parameters Based on WAAS Monitoring Data

The Wide Area Augmentation System (WAAS) is a Satellite-based Augmentation System (SBAS) developed by the United States. It broadcasts correction information in the form of message and enhances the Required Navigation Performance (RNP) for the Global Positioning System (GPS). WAAS supports most of the airspace in its service area from the RNP of route to Localizer Performance with Vertical Guidance (LPV)-200 approach. The process of decoding and the parameter extraction of WAAS message is given. The accuracy and integrity parameters in RNP indicators are analyzed, and the algorithms of accuracy and integrity indicators are described. The measured data of 34 sites in Alaska and the Continental United States are selected to calculate the accuracy and the integrity parameters. The results show that the accuracy and integrity calculation of the selected sites are basically consistent with the statistical data released by the National Satellite Test Bed (NSTB). It verifies the correctness of the message decoding and the parameter extraction algorithm, and provides reference for the construction of China's Beidou Satellite-based Augmentation System (BDSBAS).