ADS-B Single Antenna Overlapped Position Detection And Its Application

Automatic Dependent Surveillance-Broadcast(ADS-B)is a new surveillance technology that is being used worldwide by International Civil Aviation Organization.It is based on the Global Navigation Satellite System(GNSS)and data link communication,the operation monitoring technology can transmit the position information and other information of the aircraft to the ground station through the data link,it has the characteristics of higher precision,lower cost and easier maintenance compared with the traditional radar technology,therefore,the technology is widely used in civil aviation to monitor aircraft.But with the increasing number of aircraft in the airspace,the problem of overlapping of ADS-B signals becomes more and more serious.The overlapping of signals will make the information read incorrectly,so the separating technology is necessary,and the separating algorithm usually needs to detect the overlapping position first,the non-overlapping part of the signal is used for separating,so the detection of the overlapping position of the signal is an important step in the separating algorithm,but the existing detection methods of the overlapping position can not meet the requirement of the separating algorithm,single-antenna receiver is widely used because of its low cost and convenient maintenance,but there are few methods to detect the overlapping position in single-antenna separating algorithm.Therefore,this paper will mainly study the overlapping position detection method of single antenna ADS-B signal and apply the detection method to the separating algorithm to detect the feasibility of the algorithm.The main work of this thesis are as follows:Firstly,the typical single-antenna separating algorithm PASA(Projection Algorithm Single Antenna)is introduced,and the Singular Value Decomposition(SVD)of PASA is analyzed.The characteristics of ADS-B signal model and time domain waveform are summarized,which lays a theoretical foundation for the following overlapping position detection.Secondly,in the case of two signals overlapping,due to the different time-domain waveform characteristics between the signal header and the data domain,the overlapping positions are firstly classified so that the corresponding detection methods can be used when detecting the overlapping positions,which can improve detection efficiency.According to the fixity of the pulse position of the header,the overlapping position of the header is detected,and then the pulse width and amplitude of the data domain are detected.This method does not need a lot of mathematical calculation and thus improves the overall efficiency of signalseparating.Thirdly,the proposed overlapping position detection method is applied to PASA algorithm to introduce the overlapping of two signals and the overlapping of multiple signals respectively,the flow charts of overlapping position detection algorithm in the two cases are given.The complexity and error range of the proposed method are compared with the SVD decomposition method of PASA algorithm which used for overlapping position detection.The results show that the proposed method has lower complexity and smaller error range,it is more suitable for overlapping position detection of single antenna ADS-B.In addition,the factors that affect the algorithm are verified by experiments.