Research On Accuracy And Integrity Of Ground Based Augmentation System Based On GPS/BDS Constellations

With the rapid development of Chinese civil aviation, the increase of traffic, the disadvantages of Instrument Landing System(ILS) happens. Ground Based Augmentation System(GBAS) as the new generation of precision approach and landing system recommended by International Civil Aviation Organization(ICAO) can overcome the disadvantages, and its accuracy and integrity is two of the key parameters affecting the Required Navigation Performance(RNP) of this system. It is vital to research on the topic.1. This paper first introduces the development background and significance of GBAS, summarizes the development status domestically and abroad. Based on the background, We get the research about the accuracy and integrity of Ground Based Augmentation System based on GPS/BDS Constellations is not obvious.2. The composition of global navigation satellite systems(GNSS)are introduced,and the time and coordinate systems of Global Positioning System / Beidou System(GPS/BDS) are introduced, the transformation and unification between the time and coordinate systems of GPS/BDS are analyzed, and integrated positioning model of GPS/BDS is presented.3. GBAS principle is introduced, and the algorithm of pseudorange differential positioning and phase smoothing pseudorange differential positioning are analyzed. then, introducing the enhancement of accuracy and simulationing the PDOP preparing for the subsequent chapters.4. The pseudorange error model and protection level algorithm of GBAS are analyzed and researched based on GPS constellation and BDS regional constellation according to relative international standards, and relative simulations are put up. The simulation results show that integrity protection levels of GBAS under normal and fault of receivers based on GPS/BDS constellations are obviously better than that based on GPS or on BDS, and the integrity based on GPS/BDS can satisfy the requirements of integrity for Category II/III precision approach. Finally, the standards of airworthiness and GBAS NSE models are briefly introduced.