Research On Anti-spoofing For Satellite Navigation Based On Array

Global Navigation Satellite System(GNSS)is widely used in various fields,but because of its vulnerability to invasion,it is vulnerable to various of environmental interference and intentional interference.The existence of these interference seriously affects the navigation and positioning accuracy of GNSS receiver.Compared with unintentional interference caused by environment,intentional interference,which is carried out purposefully and systematically,is more threatening.Intentional interference can be divided into suppressive jamming and spoofing.Suppressive jamming usually destroys the acquisition and tracking of satellite signals by transmitting high-power signals to GNSS receivers.The attack mode of spoofing is more complex.Because of its signal characteristics in time-frequency domain can be exactly the same as real signals,spoofing is more difficult to detect and identify.With the development of technology,the attack of spoofing is more and more destructive to GNSS system.The research of anti-spoofing method is a key problem to be solved urgently in the field of GNSS.In this paper,Global Position System(GPS)system is taken as the research object.Firstly,this paper introduced the composition and positioning principle of GPS system briefly and analyzed The generation mechanism of spoofing and its signal characteristics in space and frequency domain.The characteristics of deception jamming in time and frequency domain can be almost identical with that of real signal,so deception signal is probably coherent signal.Aiming at this characteristic,this paper studied various of Direction of Arrival(DOA)estimation methods,and then selected a suitable decoherent DOA estimation algorithm for deception environment from them.On the other hand,the spatial information of deception signal and real satellite signal is difficult to achieve exactly the same.In practical applications,the deceiver usually adopts the mode of transmitting deception signals from multiple satellites to the jamming target by a single jammer.This way can control the clock synchronization of deception satellite signal well,but the deception PRN signals broadcast by this way are inevitable in the same space angle.Using this feature,the detection method of deception signal is given.Most of the traditional anti-deception jamming methods can only be applied to specific scenarios,and usually do not study the coherence of deception signals,so the anti-spoofing performance is limited.To solve these problems,a spoofing detection and elimination strategy based on multi-antenna beam space DOA estimation and space-time null control technology and beamforming technology is proposed in this paper.This method detects the direction of all signal sources in the desired space effectively by DOA estimation technology of coherent signals.The received signals are captured cyclically by beamforming algorithm which divides channels according to the direction of the source.The spatial angle and satellite number of the signals are obtained and the existence of deception jamming is detected accordingly.Then the signal of Deception Jammer is suppressed by space-time adaptive nulling technique.Finally,the space-time adaptive beamforming technology is used to improve the tracking stability of the receiver tracking loop for real satellite signals and achieve the purpose of jamming suppression.