Spoofing Interference Detection And Suppression Method Of Satellite Navigation Receiver

Global Satellite Navigation System(GNSS)has been widely used in both military and civilian fields.Due to the fragility of satellite signals,satellite navigation receivers are extremely susceptible to interference signals.The existence of man-made interference such as spoofing interference and suppressed interference affect the navigation and positioning accuracy of the GNSS receiver greatly.Because the suppressed interference power is much higher than the real satellite signal,it is easy to be detected by the receiver during its implementation.The spoofing signal is consistent with the real satellite signal in the time and frequency domain,making it difficult to be recognized by the receiver,so spoofing interference attacks are more complicated and poses a more serious threat to GNSS.Anti-spoofing interference technology in satellite navigation receivers has become a key research object in various countries around the world.This thesis studies the detection and suppression methods of spoofing interference in GNSS.The main contents are as follows:(1)Becase the classic spoofing interference detection method will be out of work when the time delay is too small or when the spoofing signal is transmitted by multiple spoofing sources,a space-time two-dimensional joint spoofing interference detection method is proposed.The satellite signals are mutually coherent signals,and the spatial smoothing algorithm is studied to realize the Direction of Arrival(DOA)estimation of the coherent sources.In order to filter the signal in the spatial domain,the beamforming theory using the minimum power principle and the direct matrix inversion algorithm to solve the optimal weight is studied.For the proposed method,the Pseudo Random Noise(PRN)code correlation detection method and decision theory are introduced.Simulation experiments show that spoofing interference detection based on spatial DOA estimation and time-domain PRN code correlation can not only accurately detect whether there is spoofing interference,but also judge the direction of the signal.(2)Because of the low practicability and the little limited application scenarios of classic spoofing interference suppression methods.A spoofing interference suppression method based on the nulling antenna is proposed for the detection results of the above spoofing interference.The theory of nulling antennas and the method of solving weights are studied,and the existence of channel errors of the receiver array whether affects the anti-interference performance of the nulling antenna is studied.Simulation experiments show that the nulling antenna can effectively suppress the spoofing interference signal in the received signal,so that the receiver will not capture the spoofing interference signal.And the existence of channel error will not affect the anti-interference performance of the nulling antenna.