Research On BD/GPS GBAS Integrity Monitoring Technique

With the development of the advanced technology of the global navigation satellite system and aviation electronic system,in order to meet the growing demand for air traffic,the International Civil Aviation Organization put forward the concept of new navigation technology "Performance Based Navigation".ICAO has reached a consensus with relevant international organizations and countries,PBN technology has been the main direction of global navigation technology.With the navigation facilities,in the designated airspace,routes and flight procedures,GNSS and its augmentation system combined with the system avionics equipment meet the requirement of PBN technology for accuracy,integrity,availability and continuity of airborne equipment,so as to realize more accurate,safe and efficient air traffic control mode.The Ground Based Augmentation System focuses on aircraft precision approach and landing,broadcasts information to the users through the ground based subsystem,The reliability of information also need to be monitored.The reliability of GBAS system used to be evaluated by the integrity,integrity monitoring technology is the guarantee of aircraft precision approach and landing performance reliability.In this paper,the integrity monitoring system of GBAS is studied,and the reliability of integrity monitoring system is verified by flight test.Firstly,this paper introduces the global navigation satellite system,introduces the space constellation structure and so on of the comparatively mature GPS system and BD system.The principles of BD/GPS single point positioning and local differential positioning are introduced in detail.The limitation of instrument landing system ILS and the advantages of GBAS system are introduced in detail.That required navigation performance requirements for precise approach of different operating types also are illustrated.Secondly,this paper introduces the structure of the GBAS ground station system and the function of each part of the system,and puts forward the innovative layout of the "three rings" style of ground reference station according to the actual situation.The algorithms of GBAS system positioning calculation and integrity monitoring are introduced in detail from the two aspects of ground subsystem and airborne subsystem.Finally,the flight test of GBAS system based on BD/GPS global navigation satellite system is introduced in detail.Through the processing and analysis on the flight test data,the results show that the GBAS based on BD system integrity performance can meet the performance requirements of CAT I aircraft approach.In terms of integrity,BD system can replaces GPS as Chinese next generation navigation source of GBAS.