GBAS Integrity Of GPS/BDS In CAT ?/?

Ground-based augmentation system(GBAS) is a kind of navigation technology to enhance the satellite navigation system. At present, GBAS has been tested to be used in Category ?precision approach, but Category ?/? GBAS precision approach is still in research. in(ICAO). In order to test if the navigation system can meet the International Civil Aviation Organization(ICAO) requirements in accuracy, integrity, continuity and availability, it is studied the GBAS for Global Positioning System(GPS) and BeiDou System(BDS) combination system's performance. In order to assess the reliability of GBAS, it makes a deep research on accuracy and integrity of this system.The structure and theory of GPS and BDS are analyzed, and the space and time are also be unified. GBAS is studied, and also its navigation system error model, which can be divided into basic theory, model theory and software simulation. Firstly, it studies two main affect factor of navigation system error(NSE), which are the different pseudo-range error sources and the constellation change. It simulates the visible constellation of single GPS or BDS and GPS/BDS, the vertical and horizontal dilution of precision accuracy factor of GBAS in these three cases, and also the two main error of NSE. By researching the requirement of navigation and GBAS service level, accuracy of the system in three cases are analyzed and compared. Finally, through the research of key integrity parameters of GBAS and the method of integrity monitoring, horizontal and vertical protection level algorithms are further researched, and be simulated by Matlab. Analyzing and comparing GBAS integrity in these three cases. The results are that the accuracy and integrity of GPS/BDS are better than single GPS or BDS, and the integrity of GPS/BDS meets the requirements of ICAO in CAT ?/?.