基于WAAS监测数据的精度和完好性参数解算

美国联邦航空管理局（FAA）建设的广域增强系统（WAAS）通过对全球定位系统（GPS）所需导航性能（RNP）的全面增强，目前已能在WAAS服务区的绝大部分空域支持从航路到具有垂直引导满足航向信标性能（LPV）-200进近的RNP.本文给出了WAAS报文的解码过程，结合WAAS广播报文阐述了精度和完好性参数的解算处理过程.选取美国阿拉斯加州和美国本土34个WAAS监测站的实测数据，按该处理流程解算出精度和完好性参数.结果表明，所选监测站位置的精度和完好性解算结果与美国国家卫星测试台（NSTB）公布的统计数据基本吻合，验证了报文解码以及参数提取算法和流程的正确性.WAAS精度和完好性参数解算处理流程可为中国北斗星基增强系统（BDSBAS）建设提供借鉴和参考. 

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).