Research On Flight Separation Assessment Method Based On Space-based ADS-B

Satellite-based Automatic Dependent Surveillance-Broadcast?ADS-B?is an essential technical solution to provide wide-area aircraft surveillance.Satellite-based ADS-B and the ground-based ADS-B are essentially the same,however because of the longer space transmission distance and the longer distance between satellites,some data quality parameters are different,the report update interval and the report transmission latency will increase while the report update probability will decrease for satellite-based ADS-B.For those reasons,it's necessary to analyze whether the separation standard used for ground-based ADS-B still validates for satellite-based ADS-B.The main contents of this thesis are:1.To analyze whether the safety level of the satellite-based ADS-B using the 5 NM separation standard could meet the target level of safety established by ICAO in the non-radar area for parallel tracks,the surveillance separation error probability?SSEP?model is used to calculate the safety level.Firstly,the evaluation methods used in surveillance performance analysis are introduced,and the computing formulas of SSEP and CAP are obtained,subsequently,the surveillance position error of aircraft using satellite-based ADS-B is analyzed and the baseline reference separation for mono-pulse secondary surveillance radar?MSSR?is computed.Finally,based on the“compared with the reference system”method,the probability of surveillance separation error greater than the baseline reference separation for satellite-based ADS-B is computed,afterwards compared with the target level of safety.The theoretical calculation shows the surveillance separation error probability is2.98?10^-15,which indicates the 5 NM separation standard can meet the target level of safety in the non-radar area for parallel tracks.2.There are various surveillance position errors for satellite-based ADS-B,so it is difficult to accurately calculate the real probability distribution for each surveillance position error using only the Gaussian distribution.Thus composite probability distributions?Gaussian distribution,double exponential distribution,uniform distribution?are used to analyze the effects of distribution type on SSEP for satellite-based ADS-B,the results indicate that the uniform distribution has the most significant influence compared to others.