Research On Preamble Detection Technologies Of Multichannel ADS-B

The preamble detection technology of ADS-B is studied in this paper.The SNR of received signal has a large dynamic range,therefore,the traditional detection methods cannot meet the high dynamic SNR environment.What’s more,ADS-B is easily subject to spoofing,the multi-channel ADS-B receiver mainly uses DOA estimation technology to resist spoofing interference,the incident signal can be filtered in space domain by beamforming technology and the target signal can be extracted.In this paper,the DOA estimation method combined with the characteristics of 1090 ES signal is studied to improve the estimation performance,a multi-channel preamble detection scheme based on beamforming is proposed.The effective working range of multi-channel ADS-B receiver is guaranteed.Firstly,the S mode data link and the specific format of 1090 ES are introduced,the mathematical model of 1090 ES is established,the correlation of 1090 ES signal is analyzed,and the principle of multi-channel ADS-B receiver ground station is expounded.Secondly,to solve the problem of high false alarm rate for the preamble detection in low SNR environment,a preamble detection method based on CA-CFAR is proposed to meet the high dynamic SNR environment.Then,a double threshold detection method is proposed to deal with the false alarm at different positions during the message.The simulation results show that the detection method based on CA-CFAR has good detection performance for a fixed false alarm rate,and the double threshold method has good detection performance and false alarm suppression ability.Then,based on the array theory,several classical DOA estimation methods based on the uniform linear array are studied,and the DOA estimation for 1090 ES source is simulated.The simulation results show that the method based on subspace has higher estimation accuracy,but is very time-consuming.Next,the DOA estimation algorithm combining the time domain characteristics of1090 ES is studied.Firstly,the cyclo-stationary algorithm is introduced,and the cyclo-stationary characteristics of 1090 ES signals are analyzed,which can be used for signal sorting.Then,the DOA estimation method based on correlation accumulation is proposed to solve the problem that the data covariance of classical subspace algorithm does not make sufficient use of the correlation of signal and noise.The simulation results show that the direction finding accuracy for 1090 ES is better under low SNR.Finally,a multi-channel ADS-B preamble detection scheme based on beamforming is proposed,under the condition of target signal and interference signal incident at the same time,the DOA estimation and beamforming are used to do a spatial filtering in order to accurately extract and recovery target signal in the mixed signal,then detect the preamble.The effectiveness of the proposed scheme is verified by simulation experiments.