The Design And Application Of Quality Monitoring Algorithm For Ground-based Augmentation System

The traditional instrument landing system can no longer meet the increasingly busy air transportation,and the ground-based augmentation system as a new type of satellite navigation-based local augmentation system proposed by the US Federal Aviation Administration can guarantee the precision approach and safe landing of civil aviation aircraft.The quality monitoring algorithm is the main part of the integrity algorithm in the ground-based augmentation system.The research and improvement of the quality monitoring algorithm can effectively improve the navigation performance of the whole system.The project is sourced from the research project of the China Electronic Technology Group Corporation Research Institute,which has certain practical application value.The main work of this paper includes the following aspects:(1)As the first set of ground-based augmentation system equipment in China,we first start from its overall structure,and understand and master the system working principle,the functions of each part and the performance of the system under Class I accuracy.Secondly,in view of the problems in the continuous long-term operation of the ground-based augmentation system in the Airport,the algorithms applied in the ground-based augmentation system are deeply studied.(2)For the problem of abnormal integrity alarm during the continuous operation of the ground-based augmentation system in the Airport,the relevant integrity data in the warning is extracted.There are more noise points in the three related parameters(Acc,Ramp,Step),and the trend of data distribution is problematic.Through the visual analysis of the data,it is found that the replacement of the satellite's ephemeris will introduce new errors.By preprocessing the data at these time points,the noise points can be reduced significantly and the data can be kept in a reasonable range.Therefore,the problem of measurement quality monitoring data hopping caused by satellite clock hopping is solved when the ephemeris is replaced.(3)For the ground-based augmentation system,the carrier-to-noise ratio(CN0)and the code-based separation degree(Dvgc)are exceeded frequently during the operation of Tianjin Binhai International Airport.Improvements in the calculation of the thresholds of these two integrity parameters by using existing data,and the new threshold and data are used for simulation experiments.As a result,the envelope of the monitoring data at the low elevation angle of the satellite is significantly better than the old threshold,and the data overrun phenomenon is solved.After the algorithm is improved and verified,the device program in the system is updated.Flight tests under Class I accuracy were carried out at the Airport,and the test results were fully meet the performance indicators.