With the continuous development of science and technology,navigation systems have been widely used in various fields and are irreplaceable.But because the navigation satellites are distributed at an altitude of more than 1,000 kilometers from the ground,the signal reaches the ground extremely weakly.Taking the L1 frequency band as an example,the minimum signal power reaching the ground is about-160 dBW.The maximum is about-153 dBW.For the receiver,its input signal-to-noise ratio is small,and the modulation mode is widely known.Therefore,it is vulnerable to intentional or unintentional electromagnetic interference or deception around,which makes the final positioning system unable to locate,so the development of anti-interference technology is urgently needed.In order to accurately locate in the interference environment,this thesis preprocesses the received data and filters out the interference signal,so as to locate and settle the ‘pure'navigation signal.This thesis mainly proposes an improved SRV broadband anti-jamming algorithm under TDL structure,and an algorithm based on navigation signal characteristics using RELAX algorithm combined with subspace projection for deceptive interference suppression,which suppresses suppressed interference and deceptive interference respectively.The improved SRV broadband anti-jamming algorithm based on TDL structure is a linear constrained minimum variance(LCMV)algorithm with improved spatial response deviation(SRV)factor under the tapped delay line(TDL)structure.Based on the space-time joint processing of wideband array signals,the algorithm improves the frequency invariance of the array response by increasing the SRV constraints,and combines the linear constrained minimum variance criterion.Finally,the Frost gradient algorithm is used to obtain the weight vector,which is sufficient to generate a deep null in the interference direction,and retain useful signal.Based on the subspace projection deceptive interference suppression algorithm,the traditional deceptive interference suppression algorithm does not consider the judgment error caused by noise instability.In this thesis,the interference angle and phase characteristics are used to determine the interference by determining the signal arrival angle and amplitude.The signal uses subspace projection technology to suppress the interference signal,which can effectively detect and suppress the forward-type high-power interference signal. |