Integrity Monitoring Of The Airport GNSS Receiving&Monitoring System

With satellite navigation system has been utilized in many area,it is not so popular in aviation flight area.The main reason is the navigation system can't satisfy all the flight phases' requirement in the following aspects:the resolution,integrity,continuity and availability.Taking resolution as example,without the influence of SA,the resolution of the GPS can only reach to 15-25m which can satisfy the requirement from route to non-precision approach phase(220m),but not the precision approach phase.For the more important,the monitoring time is too long for GPS to monitor the system integrity by itself,which would cost tens of minutes to several hours.So it is necessary to monitor the system integrity using some other technology method.This paper introduces the development situation,analysis the application in civil aviation and conducts the practical experiment in Shijiazhuang Zheng Ding International Airport according to the requirement of the system integrity.The monitoring&receiving system uses parallel processing mode with four monitoring equipment to complete the monitoring system.I mainly do the back-end data processing,independently complete of the carrier phase smoothing,differential correction value calculation,differential correction error estimation and signal quality monitoring four algorithm modules work and designed the signal quality monitoring display interface,Linking the signal quality monitoring algorithms and display interface,real-time monitoring signals whether abnormal..Firstly,select four locations in airport where the electromagnetic environment is so complex.Then set four receiving system in the selected locations and collect the satellite navigation data.Secondly,use the ground subsystem to receive navigation signal and data and complete the collection of ephemeris data,time delay of ionized layer,satellite pseudo range and precision time.Then compute the satellite difference correct information and monitor the pseudo range correction error using serials of integrity monitoring algorithms.According to the principle of the carrier smoothing eliminate the receiver thermal noise and the multipath errors of the code measurement.According to the theory of local area differential positioning remove the ephemeris,the star clock,the ionospheric delay and the troposphere delay error.Complete the estimation of the standard deviation and the deviation in real time and the calculation of the aircraft protection threshold.Establish three models of possible fault based on the signal quality monitoring of the received observations and use the correlation peak waveform to determine fault types according to the correlation peak monitoring principle.The signal quality monitoring can detect whether the received ranging code deformation anomaly or not,at the same time ensure the power of received satellite signal meet the system requirements.Compared with the Civil cross guide,radar and positioning technology,this technology greatly improves the localization accuracy,reduces the probability of failure,The signal quality monitoring can reduce the probability of failure,increases safety and reliability of civil aviation.