Research And Simulation Of Spcaed-baced ADS-B Message Decoding And Target Location Algorithm

Limited by the varied terrain and boundless ocean,the land-based Automatic Dependent Surveillance-Broadcast(ADS-B)is unable to cover global aviation surveillance.At the same time,the space-based ADS-B system can achieve global coverage but suffers from some unsolved issues.These critical issues include i)the message overlapping problem which calls for more complex decoding algorithm,ii)the low accuracy of some radiation sources in the ADS-B system which may lead to the regulatory difficulties,and iii)the security vulnerabilities in ADS-B system.These issues would degrade the efficiency of aviation surveillance systems,even threaten the national security.To address these problems,this thesis improves the space-based ADS-B system by using the electronic reconnaissance mode of satellites.In detail,this thesis first introduces the message decoding algorithm of satellite ADS-B and then analyze the error and performance of passive locating in satellite ADS-B system.Afterwards,two methods,a frequency compensation based dual-star time difference/frequency difference joint passive locating method and a motion model-based mono-star approximate passive locating method,are explicitly presented.After that,this work ameliorates the locating precision of the radiation sources through message decoding and aforementioned locating methods.Finally,the techniques for justifying the fake trajectory of radiation sources are proposed.The main contributions of my thesis are threefold:(1)Space-based ADS-B and land-based ADS-B in signal transmission are analyzed and compared.Besides,message decoding algorithm with high sensitivity,which targets space-based ADS-B environment,is studied.(2)Based on the signal transmission environment of space-based ADS-B,feasible observation parameters are selected for different observing models.In addition,proper mathematical models are established.Effects for emitter locating performance of measurement errors caused by different parameters,geometric distribution of observing stations,and other factors are simulated.GDOP maps of locating performance are illustrated.A passive locating algorithm suitable for models of rare observing stations are proposed.(3)Kalman filter and target maneuver model are studied.Under the motion model of constant velocity,constant acceleration and constant turn,the tracking and locating performances of emitter trajectory filtering using the unscented Kalman filter algorithm is analyzed,respectively.The radiation source trajectory filtering is realized by combining the message decoding and passive location,and the false trajectory of the radiation source is distinguished by passive location.