Researches On GNSS Vulnerability Assessment Methods And Intergrated Tests

Global and continuous positioning,navigation and timing(PNT)service is a key advantage of Global Navigation Satellite System(GNSS).Nonetheless,the PNT services offered by GNSS could be threatened by factors such as system failure,ionospheric anomaly and radio frequency interference(RFI),which are collectively named as GNSS Vulnerability Factors(VF).Therefore,researching on GNSS vulnerability is significant to improving the reliability of GNSS PNT service.Researches on GNSS vulnerability can be classified into two categories,namely,interference detection and mitigation(IDM),and GNSS vulnerability assessment(GVA).The thesis focuses on GVA,which means assessing GNSS vulnerability according to different service requirements of different GNSS applications,and flagging an alarm signal to users when GNSS service is damaged by VF.The primary contributions of the thesis are but not limited to,a)This work clarifies several GNSS vulnerability-related concepts once vaguely defined.It shows the relationship between GNSS vulnerability and GNSS integrity on the basis of the four traditional GNSS service performance indicators(accuracy,integrity,continuity,and availability).In addition,it classifies GNSS applications into six categories based on different service requirements,and proposes a new research method of GNSS vulnerability analysis.b)The thesis selects C/N0,??,GDOP as assessment indexes,proposes for the first time an information entropy weight based GNSS vulnerability assessment method for vehicle applications,of which the field test has been carried out in the urban areas of Shanghai.Then a method of constructing a GNSS vulnerability map of urban road networks is put forward.c)The thesis analyzes GNSS applications in CNS/ATM system,proposes for the first time a GNSS integrity monitoring based GNSS vulnerability assessment method for GNSS applications in civil aviation.First a real-time GNSS vulnerability assessment method in civil aviation is proposed,based on which a real-time GNSS vulnerability assessment software(C/C++)is presented.Then a method of assessing GNSS vulnerability of airlines in CNS/ATM is proposed.d)GNSS vulnerability experiment platforms based on vehicle and unmanned aerial vehicle(UAV)are constructed;multiple vehicle and flight tests have been conducted to validate the algorithms in b)and c).