Design Of Key Algorithms And Software Development For Integrity Monitoring Of Ground Based Augmentation System

Global Navigation Satellite System(GNSS)is widely used in the fields of transportation,mapping,military affairs,survey,weather forecast,and geological disaster monitoring.The accuracy of the navigation System is the degree of consistency between the calculated location and the real location.Ground Based Augmentation System(GBAS),based on the principle of differential localization,can reduce or eliminate some errors in the localization process,then improve the accuracy of positioning.The integrity of the Ground Based Augmentation System refers to the ability of the system to send an alarm in time if the system occurs failures or the error of the difference correction exceeds the allowable range.In order to broadcast accurate and fault-free difference correction information to users,it is necessary to monitor the integrity of the system before broadcast the difference correction information.The main works and results of this paper are as follows:(1)This paper investigates the satellite navigation system and the integrity monitoring of ground based augmentation system,then summarized the research status from the aspects of single-base station integrity and multi-base station networking performance.(2)The single base station integrity monitoring algorithms are summarized,including Signal Quality Monitoring(SQM),Data Quality Monitoring(DQM),Measurement Quality Monitoring(MQM),difference algorithm and message monitoring.Some algorithms are improved to make the monitoring results more intuitive and the monitoring logic more reasonable.Based on the measured data,the above algorithm is simulated and verified by MATLAB,and the monitoring variable and threshold of each monitoring step are obtained.(3)The Multiple Reference Consistency Check(MRCC)is simulated by MATLAB,using the observation data of four base stations simulated through the simulator.The B value in MRCC is calculated,to monitoring and eliminating the fault of a base station by the change of the B value.Multi-base station ground based augmentation system usually has better performance and smaller error than single base station.However,the number and configuration of multi-base station network are important factors affecting the performance of multi-base station system.The observation data of 8 base stations are simulated through the simulator,to study the influence of different factors on the network performance of base stations.The network performance is reflected through the calculation of Horizontal Protection Level(HPL),and the conclusion is drawn finally.(4)This paper designed and developed the integrity monitoring software based on Android system.The software can read the observation data of single base station and multiple base stations and conduct integrity monitoring respectively.The monitoring steps include some of the above verified and improved algorithms.The software has the functions of reading data,storing data,monitoring operation,displaying results and alarm of failure.There are 81 pictures,7 tables and 57 references in this paper.