Performance Analysis And Research Of Airborne GBAS VDB Equipment

At present,Instrument Landing System(ILS)is the main precision approach and landing system used in civil aviation,but its inherent defects make it increasingly unable to meet the requirements of civil aviation development.Ground-Based Augmentation System(GBAS)can not only solve the inherent defects of ILS,but also provide higher standard required navigation performance(RNP),which is an important choice for the next generation of precision approach and landing system.The airborne VHF Data Broadcasting(VDB)equipment is an important part of the airborne GBAS.It combines the airborne GBAS Positioning and Navigation(PAN)equipment to guide the aircraft through the specified RNP to complete the precision approach and landing.At present,the research on GBAS is mostly focused on VDB signal format and VDB signal coverage,while the research on the performance of airborne VDB receiver is rare.In view of this situation,this paper studies the performance of airborne VDB receiver,including demodulation performance,main performance index analysis and anti-jamming performance of airborne VDB receiver.Firstly,the demodulation performance of airborne VDB receiver is studied.The structure and modulation method of the VDB signal specified in the GNSS-based Precision Approach Local Area Enhancement System(LAAS)Spatial Signal Interface Control Document(DO-246D)standard issued by the American Radio and Radio Technical Committee(RTCA)is detailed.Differential 8-Phase Shift Keying(D8PSK)modulation is applied to it,then coherent demodulation algorithm and differential demodulation algorithm are used to demodulate VDB signal,and the anti-noise performance of the two algorithms is compared.Then,the main performance indicators of airborne VDB receiver are studied.According to the content of the Minimum Operating Performance Standard for Airborne Equipment in GPS Local Enhanced System(DO-253D)promulgated by RTCA,the main performance indicators of airborne VDB receiver are determined,including response time,sensitivity,dynamic range and carrier tracking.Therelationship between a performance index and related parameters is studied,and the corresponding simulation is given.Finally,the anti-jamming performance of airborne VDB receiver is studied.According to the interference of airborne VDB receiver mentioned in RTCA DO-253 D standard,it mainly includes co-channel interference,adjacent channel interference and out-of-band interference,and corresponding methods and measures are adopted to suppress the interference.The co-channel interference of the airborne VDB receiver is studied in detail.The blind signal separation method is proposed to suppress it,and the feasibility of this method is verified.