Research On GNSS Interference Detection And Identification Technologies

Global navigation satellite system can provide time,location,speed information at anytime and anywhere.Moreover,it can realize navigation,high-precision positioning,and time service in real time,which brings great convenience to people's lives and has been widely used in all walks of life.However,because satellite navigation signals are susceptible to various types of intentional or unintentional interference,which has great influence on navigation application security,it is urgent to develop GNSS interference monitoring system to provide decision basis for responding to interference.Interference detection and identification technology are the key issues of the interference monitoring system.The thesis combined the features of GNSS signals and interference signals,and focused on interference detection and interference identification in GNSS interference monitoring system for suppressed interference and modulated interference.The main contents are as follows:(1)The thesis analyzed interference signals and the features of GNSS signals,constructed models of interference signals.Besides,the impacts of interference on navigation receivers were explored.Then,the overall structure of GNSS interference monitoring system was given,and the key technologies were analyzed.(2)In order to meet the requirements of high-reliability interference detection in complex electromagnetic environment,considering the realization requirements,the thesis took the energy detection method that is simple to implement and does not require prior information to perform interference detection.Moreover,the thesis studied the detection performance of the algorithm under various types of interference,and analyzed the influence of sampling length and false alarm probability on detection probability by simulation.(3)Based on multi-node cooperation,a dual-threshold cooperative interference detection algorithm was designed against the problem of performance degradation at low JNR caused by the noise detection uncertainty in GNSS environment.According to the channel environment of each node,a multi-node information fusion and detection algorithm based on credibility was adopted,which can make the data fusion of the fusion center tend toward the node with good channel environment.Then,the thesis verified the algorithm has good detection performance at low JNR.(4)An adaptive dual-threshold cooperative detection algorithm was proposed to solve the high computational complexity of the dual-threshold cooperative detection,it can reduce the computational complexity while ensuring the detection performance by adjusting the distance between double thresholds in real-time through noise environment.And then the influence of the adjustment factor and channel environment threshold on the algorithm was analyzed by simulation.(5)The thesis designed the pattern identification-based interference identification technology and focused on the analysis of feature extraction,classifier design and classification decision.Based on interference identification strategies of decision tree and support vector machine,interference signals were identified with the extracted feature parameters of high-order cumulant,3dB bandwidth of the normalized spectrum,frequency modulation based on short-time Fourier transform and single frequency component detection.The simulation results showed that the design scheme can realize the classification and identification of typical suppressed and modulated interference signals.